API Management in Azure – RFC v3.3

Post by: syed hussain in All Architecture Best Practice Microsoft Azure

Change Log

changelog:
  - version: 0.1
    description: 
      - Initial draft released, covering fundamental best practices such as security (JWT validation), performance optimisation (caching), and basic quota management.
  - version: 1.2
    description: 
      - Added OAuth 2.0 integration with Azure AD, expanded error-handling policies, and introduced API mocking for early testing.
  - version: 2.0
    description: 
      - Introduced advanced content-based routing for dynamic backend selection, response caching strategies, and token-based authentication using third-party identity providers.
  - version: 3.3
    description: 
      - Enhanced API security with mutual TLS, improved quota and rate limit management, and included guidance for distributed tracing and real-time monitoring using Azure Monitor.

API Management

1. Understand the Basic Components of API Management

Azure API Management (APIM) consists of three main components:

  • API Gateway: This component abstracts the backend architecture, allowing APIs to be exposed securely. It manages all API requests, applies policies, authenticates users, and forwards requests to backend services.
  • Management Plane: Administrators use this component to manage APIs, products, users, and policies. It can be accessed via the Azure Portal, CLI, PowerShell, or ARM templates.
  • Developer Portal: This is the consumer-facing component. API consumers use the portal to discover, explore, and onboard APIs. It provides API documentation and self-service key generation.

Implementation: Deploy an API Management service from the Azure Portal, CLI, or using ARM templates. Provision APIs and bind them to the gateway. Configure the developer portal by customising the UI and documentation.

2. Ensure API Gateway Abstraction of Backend Architecture

The API Gateway in APIM abstracts backend services, allowing you to make internal services available to external consumers without exposing your internal architecture.

Implementation:

  • Create an API in APIM, and map each operation (e.g., GET, POST) to backend URLs. For example, map the external endpoint /api/products to an internal microservice https://internal-products.service.
  • Use policies to hide sensitive headers, rewrite URLs, or modify request/response payloads.

Policy Example:

<inbound>
    <base />
    <set-header name="X-Internal-Header" exists-action="delete" />
    <rewrite-uri template="/new-products/{product-id}" />
</inbound>
<backend>
    <forward-request />
</backend>
<outbound>
    <base />
</outbound>

This policy deletes sensitive internal headers and rewrites the incoming request URI before forwarding it to the backend.

3. Verify API Keys and Credentials (e.g., JWT Tokens, Certificates)

APIM allows securing your APIs with multiple authentication schemes, including API keys, JWT tokens, and certificates. You can enforce API key validation or integrate with OAuth 2.0 for token validation.

Implementation:

  • Use policy expressions to validate API keys.
    For instance, restrict access to an API using API keys by setting up an inbound policy that checks for the presence of an API key in the request.

API Key Validation Policy:

<inbound>
    <base />
    <validate-header name="Ocp-Apim-Subscription-Key" failed-request-message="API key required" />
</inbound>
  • To validate JWT tokens, use the validate-jwt policy:
<validate-jwt header-name="Authorization" failed-validation-httpcode="401" failed-validation-error-message="Invalid token" require-scheme="Bearer">
    <openid-config url="https://login.microsoftonline.com/{tenantId}/v2.0/.well-known/openid-configuration" />
    <audiences>
        <audience>your-audience</audience>
    </audiences>
</validate-jwt>

This validates a JWT token against Azure AD.

4. Enforce Quotas and Rate Limits on API Usage

To protect your APIs from misuse, APIM allows you to set quotas and rate limits for API consumption. You can enforce these limits on a per-user, per-product, or per-subscription basis.

Set a rate-limit policy to restrict the number of requests per minute, hour, or day:

<inbound>
    <base />
    <rate-limit-by-key calls="100" renewal-period="60" counter-key="@(context.Subscription.Id)" />
</inbound>

This policy limits each subscription to 100 calls per minute.

Use the quota-by-key policy for long-term quotas (e.g., monthly limits):

<inbound>
    <base />
    <quota-by-key calls="1000" renewal-period="2629746" counter-key="@(context.Subscription.Id)" />
</inbound>

This enforces a monthly quota of 1,000 calls per subscription.

5. Optionally Transform Requests and Responses via Policy Statements

APIM allows you to transform incoming requests or outgoing responses, including modifying headers, changing the payload format, or even routing requests to different backends based on conditions.

Use rewrite-uri or set-header policies to modify requests:

<inbound>
    <base />
    <rewrite-uri template="/v2/{product-id}" />
    <set-header name="Authorization" exists-action="override">
        <value>Bearer token-value</value>
    </set-header>
</inbound>

To transform a response, use an outbound policy. You can convert XML responses to JSON:

<outbound>
    <base />
    <xml-to-json apply="always" />
</outbound>

6. Configure Response Caching to Reduce Backend Load

Caching responses in APIM can reduce the load on backend services by serving cached data for repeated requests. You can configure caching based on request parameters or specific responses.

Enable caching for a specific API response using the cache-lookup policy:

<inbound>
    <base />
    <cache-lookup vary-by-developer="true" vary-by-developer-groups="false" />
</inbound>

Set the cache-store-duration to define how long the cache should be valid:

<outbound>
    <base />
    <cache-store duration="300" />
</outbound>

This caches the response for 5 minutes (300 seconds).

7. Emit Logs, Metrics, and Traces for Monitoring, Reporting, and Troubleshooting

Monitoring is a key part of managing an API’s lifecycle. APIM integrates with tools like Azure Monitor, Application Insights, and Log Analytics to collect metrics and logs for real-time insights and troubleshooting.

Enable Application Insights to trace request telemetry from APIM.

<inbound>
    <base />
    <set-variable name="request-id" value="@(context.Request.Id)" />
</inbound>

In the Azure Portal, link your API Management instance with Azure Monitor to track request metrics such as response time, request volume, and failure rates.

8. Consider the Use of a Self-Hosted Gateway for Hybrid and Multi-Cloud Environments

APIM’s self-hosted gateway allows you to run the gateway component in environments outside of Azure, such as on-premises or in other cloud platforms.

Deploy the self-hosted gateway in a Docker container:

docker run -d -p 8080:8080 \
  -e APIM_HOST_GATEWAY_ID=<gatewayId> \
  -e APIM_HOST_ENVIRONMENT=<env> \
  mcr.microsoft.com/azure-api-management/gateway:latest
  • Use Kubernetes to deploy the self-hosted gateway and scale it according to traffic needs.

9. Deploy the Self-Hosted Gateway Using Linux-Based Docker Containers

You can deploy the self-hosted gateway using Linux-based Docker containers for environments where you need to keep traffic local or manage APIs outside of Azure.

Install Docker on your target Linux server and run the self-hosted gateway container as described above. Ensure that you configure the environment variables to connect the self-hosted gateway to your Azure API Management instance.

10. Use Kubernetes for Self-Hosted Gateways

For more complex deployment scenarios or large-scale environments, use Kubernetes (AKS) to manage your self-hosted gateways. Kubernetes offers auto-scaling and orchestration capabilities for managing API traffic.

Create a Kubernetes deployment for the self-hosted gateway:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: apim-gateway
spec:
  replicas: 3
  selector:
    matchLabels:
      app: apim-gateway
  template:
    metadata:
      labels:
        app: apim-gateway
    spec:
      containers:
      - name: apim-gateway
        image: mcr.microsoft.com/azure-api-management/gateway:latest
        env:
        - name: APIM_HOST_GATEWAY_ID
          value: <gatewayId>
        - name: APIM_HOST_ENVIRONMENT
          value: <env>

11. Provision and Configure API Management Service via Management Plane

The Management Plane allows administrators to provision, configure, and manage the API Management service using the Azure Portal, CLI, or automation tools like ARM templates.

To provision an API Management instance using the Azure CLI:

az apim create --resource-group myResourceGroup --name myAPIM --location eastus --publisher-email admin@mycompany.com --publisher-name "MyCompany"

Use ARM templates for repeatable deployments:

{
  "type": "Microsoft.ApiManagement/service",
  "apiVersion": "2021-01-01-preview",
  "name": "myAPIMService",
  "location": "East US",
  "properties": {
    "publisherEmail": "admin@mycompany.com",
    "publisherName": "MyCompany"
  }
}

Use the Azure Portal or Azure REST API to perform ongoing management, such as adding new APIs, updating policies, or configuring network settings.

12. Define or Import API Schemas from Various Sources (OpenAPI, WSDL, OData, etc.)

API Management allows you to define or import API schemas, including those from OpenAPI (Swagger), WSDL, or OData definitions. This enables easy integration with existing services.

To import an OpenAPI definition, use the Azure Portal:

  • Navigate to APIs > Add API > OpenAPI.
  • Upload your OpenAPI JSON/YAML file or provide the URL.
  • You can also import WSDL files for SOAP APIs:
    • Select SOAP under Add API and upload the WSDL file.
  • Automate the process using the CLI:
az apim api import --resource-group myResourceGroup --service-name myAPIM --path "/myapi" --specification-format OpenAPI --specification-path myAPI.json

13. Package APIs into Products for Ease of Management

APIs can be grouped into Products in API Management. A product bundles APIs with specific usage quotas, subscription keys, and visibility settings, which can then be assigned to specific developer groups.

Create a product in the Azure Portal under API Management > Products > Add Product.

  • Assign multiple APIs to the product.
  • Set usage quotas (e.g., 1000 calls/month), rate limits, and visibility options.
  • Use the Azure CLI to create a product:
az apim product create --service-name myAPIM --resource-group myResourceGroup --product-id myProduct --display-name "Standard Product" --subscription-required true

14. Apply Policies Like Quotas and Transformations to APIs

API policies are a powerful feature in APIM that let you enforce rules like quotas, security requirements, and transformations at different levels—globally, at the product level, or at the API or operation level.

Apply a quota-by-key policy to an API operation to restrict a user to 1000 calls/month:

<inbound>
  <quota-by-key calls="1000" renewal-period="2629746" counter-key="@(context.Subscription.Key)" />
</inbound>

To perform transformations, apply the xml-to-json or json-to-xml policies to convert request/response formats:

<outbound>
  <xml-to-json apply="always" />
</outbound>
  • You can automate policy application using ARM templates or the REST API.

15. Use API Management Analytics to Gather Insights

API Management provides detailed analytics, giving insights into API performance, usage patterns, and failures. You can access this data through the Azure Monitor integration, Application Insights, or directly in the API Management portal.

Enable Azure Monitor logs for API Management:

  • In the Azure Portal, go to API Management > Diagnostic Settings > Add Diagnostic Setting.
  • Select metrics and logs to forward to Azure Monitor or Log Analytics.
  • Use Application Insights for deeper monitoring. Add the Application Insights instrumentation key to your API:
<inbound>
  <set-header name="x-app-insights" exists-action="override">
    <value>instrumentation-key-here</value>
  </set-header>
</inbound>
  • Monitor the performance of each API through response times, latency, and success rates.

16. Manage Users, Groups, and Subscriptions Through the Management Plane

APIM allows the management of users and groups, enabling fine-grained control over who can access which APIs. Subscriptions are used to manage API keys and access controls.

Use the Azure Portal to create new users and assign them to specific groups:

  • Navigate to API Management > Users > Add User.
  • Assign users to predefined groups like Developers, Administrators, or Guests.
  • Create and manage subscriptions for users:
    • Go to API Management > Subscriptions > Add Subscription.
    • Link the subscription to specific products.
  • To manage users and subscriptions via CLI:
az apim user create --service-name myAPIM --resource-group myResourceGroup --user-id myUser --email "user@example.com" --first-name "First" --last-name "Last"

17. Customise the Developer Portal for API Discovery and Onboarding

The Developer Portal is a key part of API Management, allowing API consumers to explore, test, and subscribe to APIs. You can customise the portal’s look and feel to align with your brand, as well as extend it with custom functionality.

Customise the Developer Portal by changing the branding and layout:

  • Navigate to API Management > Developer Portal > Edit.
  • Use the built-in editor to modify pages, themes, and add content.
  • You can also extend the Developer Portal by adding custom widgets and scripts.
  • Enable interactive API testing in the portal, allowing users to try out APIs directly using Swagger UI:
    • Configure OAuth2 or API key mechanisms for testing.

18. Enable Self-Service API Key Generation for Developers Via the Portal

APIM’s Developer Portal supports self-service capabilities for API consumers, allowing developers to generate their own subscription keys to access APIs.

Developers can sign up for API products, generate keys, and test APIs in the Developer Portal.

  • Navigate to API Management > Subscriptions to configure self-service access.
  • Developers can choose the product they wish to subscribe to and receive API keys automatically upon approval.

19. Create Custom Groups or Use External Groups for API Visibility Management

Groups in API Management allow you to control who has access to specific APIs. You can define custom groups or integrate with external systems like Azure Active Directory to manage access.

Create custom groups in API Management:

  • Go to API Management > Groups > Add Group.
  • Assign APIs to specific groups, controlling which users can access which APIs.
  • For external groups, integrate with Azure AD:
    • Enable Azure AD authentication for user sign-in and group membership management.
    • Use RBAC policies to link external Azure AD groups with APIM.

20. Use Azure Role-Based Access Control (RBAC) to Manage Developer Access

API Management integrates with Azure RBAC to provide role-based access control at various levels, ensuring that developers, administrators, and consumers have the correct permissions.

Assign roles such as API Administrator, API Contributor, or API Reader to users or groups via the Azure Portal:

  • Go to API Management > Access Control (IAM) > Add Role Assignment.
  • Assign roles to users or groups.
  • Use the Azure CLI for role assignment:
az role assignment create --assignee <user-email> --role Contributor --scope "/subscriptions/<subscriptionId>/resourceGroups/<resourceGroup>/providers/Microsoft.ApiManagement/service/<apimInstance>"

21. Apply Policies Globally, at Product, API, or Operation Levels

API Management allows policies to be applied at different scopes, such as globally across all APIs, at the product level, or even at specific API operations.

Apply a global policy by navigating to API Management > Policies > Global Scope.

  • For instance, add an IP filtering policy to restrict access to certain IP ranges:
<inbound>
  <check-header name="X-Forwarded-For" failed-check-httpcode="403" failed-check-error-message="Forbidden IP" />
</inbound>
  • Apply API-specific policies under APIs > Selected API > Policies.

22. Explore Policy Expressions to Dynamically Configure Policies

Policy expressions allow you to create dynamic, data-driven policies based on context, environment variables, or request details.

Use policy expressions in API Management policies to dynamically configure headers or URLs:

<inbound>
  <set-header name="Authorization" exists-action="override">
    <value>Bearer @(context.Request.Headers.GetValueOrDefault("Authorization", "default-token"))</value>
  </set-header>
</inbound>

This expression checks the incoming request header for an Authorization token and applies a default if it’s not present.

23. Use XML to JSON Format Conversion as a Popular Policy Option

Converting XML to JSON is a common transformation in modern API management, allowing legacy services that use XML to be consumed by modern clients that prefer JSON.

Apply the xml-to-json policy in the API’s outbound section to transform the XML response from the backend into JSON:

<outbound>
    <base />
    <xml-to-json apply="always" />
</outbound>
  • Similarly, you can transform incoming JSON requests into XML using the json-to-xml policy if your backend expects XML:
<inbound>
    <base />
    <json-to-xml apply="always" />
</inbound>

These policies are simple to apply and allow seamless communication between clients and legacy systems.

24. Implement Call Rate Limiting to Protect APIs from Overuse

Rate limiting is an essential technique to protect your APIs from overuse and abuse. It ensures that clients don’t exceed a predefined number of requests within a given period, thereby preventing system overloads.

Use the rate-limit-by-key policy to limit the number of requests per minute or second, based on the API key or subscription:

<inbound>
    <rate-limit-by-key calls="100" renewal-period="60" counter-key="@(context.Subscription.Id)" />
</inbound>

This policy limits the user to 100 calls per minute. You can increase the granularity by using different time windows (e.g., per second or per hour) and adjusting the number of allowed calls.

25. Import APIs from Azure Compute Services or WebSocket, GraphQL, and gRPC Backends

Azure API Management allows importing and managing APIs from various backend technologies such as WebSockets, GraphQL, and gRPC, as well as more traditional REST and SOAP services.

For GraphQL backends:

  • In the Azure Portal, go to API Management > APIs > Add API > GraphQL.
  • Provide the GraphQL schema and configure operations.
  • For WebSocket APIs:
    • Set up the WebSocket URL in API Management, which allows real-time data exchanges.
  • For gRPC backends:
    • Upload the .proto files to define the API.
    • gRPC is supported in premium tiers, enabling high-performance, low-latency communication.

26. Transform and Protect APIs Using API Management Policies

You can transform incoming and outgoing data to meet specific requirements (e.g., changing headers, modifying payloads) and protect the API with security features like IP filtering and token validation.

Use policies to protect your APIs by adding JWT validation:

<validate-jwt header-name="Authorization" failed-validation-httpcode="401" failed-validation-error-message="Invalid Token" />

Apply a transformation to modify incoming requests, such as rewriting URIs or adding new headers:

<inbound>
    <rewrite-uri template="/new-path/{id}" />
    <set-header name="X-Api-Version" exists-action="override">
        <value>v2.0</value>
    </set-header>
</inbound>

27. Configure Custom Domain Names for the API Gateway

To give your API a professional and branded URL, you can configure a custom domain name for your API Gateway. This involves configuring DNS settings and certificates.

Implementation:

  • In the Azure Portal, navigate to API Management > Custom Domains > Add Domain.
  • Configure the CNAME record in your DNS provider to point to the API Management gateway domain.
  • Upload a custom SSL certificate for HTTPS traffic.

Azure CLI Example:

az apim update --name myAPIM --resource-group myResourceGroup --set hostnameConfigurations[0].certificate.keyVaultId=<key-vault-id>

28. Deploy API Management to a Virtual Network (VNet) for Secure Backend Connections

To ensure secure communication between the API Management gateway and backend services, you can deploy API Management within a Virtual Network (VNet). This isolates the traffic and ensures that API requests remain within the corporate network.

In the Azure Portal, go to API Management > Virtual Network > Enable VNet.

  • Choose between External (public access) or Internal (private access).
  • Configure the VNet to include private endpoints for your backend services.

29. Use Application Gateway and Azure Front Door for Network-Level Protection

Azure Application Gateway and Azure Front Door provide network-level protection for your APIs. They offer features like Web Application Firewall (WAF), SSL termination, and global traffic distribution.

Deploy Application Gateway in front of your API Management instance to protect against common web vulnerabilities (XSS, SQL Injection, etc.) with WAF:

az network application-gateway create --name appGateway --resource-group myResourceGroup --vnet-name myVnet --subnet-name mySubnet

Use Azure Front Door for global load balancing and improved performance for global traffic:

In the Azure Portal, configure Front Door to distribute API traffic across multiple API Management instances deployed in different regions.

30. Secure APIs with Azure Defender for APIs and DDoS Protection

Azure Defender for APIs integrates with API Management to provide enhanced security against API-related attacks, including Distributed Denial of Service (DDoS).

In the Azure Portal, go to API Management > Defender for APIs > Enable Defender for APIs.

  • For DDoS protection, enable Azure DDoS Protection in the same Virtual Network where your API Management instance is deployed:
    • In the Azure Portal, navigate to DDoS Protection Plans and configure the VNet.

31. Integrate API Management with Azure Monitor for Detailed Logging and Metrics

Azure API Management integrates with Azure Monitor to provide detailed logging, metrics, and monitoring. This helps in identifying bottlenecks, monitoring API performance, and troubleshooting issues.

  • In the Azure Portal, navigate to API Management > Diagnostic Settings > Add Diagnostic Setting.
  • Select Azure Monitor as the destination for logs and metrics.
  • Use Log Analytics queries to analyse API request trends, latencies, and errors.

32. Enable Real-Time Monitoring with Application Insights

Application Insights provides real-time monitoring for API Management. It allows you to track request traces, performance metrics, and telemetry across APIs.

  • In the Azure Portal, go to API Management > Application Insights > Enable Application Insights.
  • Set up Application Insights instrumentation keys in the API policies:
<inbound>
    <set-variable name="appInsightsKey" value="your-app-insights-instrumentation-key" />
</inbound>
  • Use the Application Insights dashboard to track real-time performance and identify anomalies.

33. Stream Logs and Events Using Azure Event Hubs

If you need to handle a large volume of API logs and events, you can use Azure Event Hubs to stream logs for real-time analysis or downstream processing.

In the Azure Portal, go to API Management > Diagnostic Settings > Add Diagnostic Setting.

  • Select Azure Event Hubs as the log destination.
  • Use Azure Stream Analytics or custom processing tools to consume and analyse the data in real-time.

34. Use Microsoft Entra ID (Azure AD) for Authentication and Request Authorisation

Microsoft Entra ID (Azure AD) provides secure authentication and authorisation for your APIs. You can configure APIs to require Azure AD tokens for access.

In the Azure Portal, configure Azure AD under API Management > OAuth 2.0 + OpenID Connect.

  • Use the validate-jwt policy in the API to enforce Azure AD token validation:
<validate-jwt header-name="Authorization" failed-validation-httpcode="401" failed-validation-error-message="Invalid Token" require-scheme="Bearer">
    <openid-config url="https://login.microsoftonline.com/{tenantId}/v2.0/.well-known/openid-configuration" />
</validate-jwt>

This ensures that only requests with valid Azure AD tokens are allowed to access the API.

35. Integrate with Azure Key Vault for Secure Management of Certificates and Secrets

Azure Key Vault helps securely manage certificates, keys, and secrets used by APIs. API Management can pull certificates and secrets directly from Azure Key Vault, ensuring that sensitive information is never exposed in plain text.

  • Store your certificates or secrets in Azure Key Vault.
  • In API Management, go to API Management > Certificates > Add > Key Vault.
  • Grant API Management access to the Key Vault by configuring access policies:
az keyvault set-policy --name MyKeyVault --spn <api-management-spn> --secret-permissions get

Use the secret in policies by referencing it with a Key Vault URI:

<set-header name="X-Api-Key" exists-action="override"> <value>@(context.Variables.GetValueOrDefault("secretUri", "default-key"))</value> </set-header>

36. Use Serverless Compute (e.g., Azure Functions) for API Hosting

You can use Azure Functions to host lightweight, serverless APIs. API Management can serve as the front-end, while Azure Functions handle backend logic without needing to manage infrastructure.

Create an Azure Function in the Azure Portal or via CLI:

az functionapp create --resource-group myResourceGroup --consumption-plan-location eastus --name myfunctionapp --runtime node --runtime-version 12
  • In API Management, add a new API that maps to the Azure Function as the backend service:
    • Go to APIs > Add API > Function App and link your Azure Function.
  • Secure the Azure Function using OAuth, API keys, or Azure AD.

37. Expose APIs Through Logic Apps or Web Apps for Workflow Automation

You can expose APIs via Logic Apps to enable workflow automation for enterprise applications, or through Web Apps for handling more complex web-based services.

Implementation:

  • Use Azure Logic Apps to build workflows that can trigger API requests:
    • In the Azure Portal, create a Logic App, and use HTTP triggers to call the API.
  • For web apps, host your backend in Azure Web Apps and link it to API Management.

Recommendation: Could – While useful for automating processes, this is not mandatory unless your API requires complex workflows or integrations with other services.

38. Use Service Fabric for Microservices-Based API Hosting

Azure Service Fabric is designed to support microservices-based architectures, which can be exposed and managed through API Management.

Deploy your microservices using Service Fabric, and expose APIs for each service using API Management:

az sf application create --resource-group myResourceGroup --cluster-name myCluster --name myMicroservicesApp --type Microsoft.Azure.ServiceFabric
  • Create an API in API Management that forwards requests to the appropriate Service Fabric microservice endpoints.

*Use this only if you are still using Service Fabric.

39. Leverage Azure OpenAI Service for AI-Driven APIs

Use the Azure OpenAI Service to provide AI capabilities in your APIs, allowing for more advanced interactions such as natural language processing or AI-driven decision-making.

  • Create an OpenAI resource in the Azure Portal, and expose the AI model via API Management:
    • Go to API Management > Add API > Custom API and link to your OpenAI backend.
  • Secure and transform responses as necessary using API Management policies.

40. Consider the Use of Autoscaling in Premium or v2 Tiers

To handle fluctuating traffic demands, you can enable autoscaling for your API Management instance in the Premium or v2 tiers, allowing it to automatically add or remove scale units based on usage.

  • In the Azure Portal, navigate to API Management > Scale > Autoscale.
  • Set conditions for scaling (e.g., when CPU usage exceeds 80%).

41. Choose the Correct API Management Tier Based on Capacity, Scalability, and Features

Azure API Management offers multiple tiers (Developer, Basic, Standard, Premium) that differ in scalability, availability, and feature set.

Select the appropriate tier based on your business requirements and traffic volume:

  • Developer Tier: Best for testing and development.
  • Standard Tier: Ideal for production APIs with moderate traffic.
  • Premium Tier: Required for advanced scenarios like multi-region deployments or VNet integration.

42. Scale API Management Gateways by Adding or Removing Scale Units

You can scale API Management gateways by adding or removing scale units, which allows you to handle larger volumes of API requests.

  • In the Azure Portal, navigate to API Management > Scale > Add/Remove Scale Units.
  • Adjust the number of scale units based on projected traffic.

43. Ensure API Management Instances Are Geo-Distributed to Reduce Latency

For global APIs, reducing latency is critical. You can deploy API Management instances in multiple Azure regions to ensure that requests are routed to the nearest gateway, improving performance.

  • Deploy API Management in multiple regions by creating additional units in those regions via the Premium Tier.
  • Use Azure Traffic Manager or Azure Front Door to route traffic to the closest API Management instance:
az network traffic-manager profile create --name myProfile --resource-group myResourceGroup --routing-method Performance

44. Configure Multiple Custom Domain Names in Premium or Standard v2 Tiers

APIM supports configuring multiple custom domains, which allows you to expose different APIs under various branded URLs.

  • In the Azure Portal, go to API Management > Custom Domains > Add Domain.
  • Set up the CNAME records in DNS for each domain and assign the correct SSL certificates for each domain.

45. Enable High Availability by Deploying to Multiple Regions

For mission-critical APIs, ensure high availability by deploying API Management in multiple Azure regions. This provides redundancy in case of regional failures.

  • In the Premium Tier, deploy additional units of API Management in multiple regions.
  • Use Azure Traffic Manager to route traffic based on regional health:
az network traffic-manager endpoint create --profile-name myProfile --name myEndpoint --type AzureEndpoints --target-resource-id myAPIMResource

46. Use API Management’s Built-In Caching to Enhance Performance

APIM’s built-in caching feature reduces the load on backend services by caching responses for repeated requests, improving response times and lowering backend workload.

Apply the cache-store policy in the API’s outbound section to cache responses:

<outbound>
    <base />
    <cache-store duration="300" />
</outbound>

This caches the response for 5 minutes (300 seconds).

47. Integrate External Redis-Compatible Caches for Advanced Caching Needs

For more advanced caching scenarios, you can integrate with an external Redis cache to manage large amounts of cached data outside of API Management.

Deploy an Azure Redis Cache instance:

az redis create --name myCache --resource-group myResourceGroup --sku Standard --vm-size c1

Use policies in API Management to forward requests to the Redis cache and retrieve responses from the cache.

48. Configure TLS Settings to Ensure Secure Communication

Transport Layer Security (TLS) ensures secure communication between clients and API Management, and between API Management and backend services. You can configure API Management to enforce strong TLS protocols.

  • In the Azure Portal, navigate to API Management > Custom Domains > TLS/SSL Settings.
  • Choose the minimum supported TLS version (e.g., TLS 1.2).
  • Upload your SSL certificate to secure the communication between clients and API Management.

*Configuring TLS is mandatory for any public API to ensure secure communication and compliance with security standards.

49. Use Client Certificate Authentication for Enhanced Security

Client certificates can be used to authenticate API requests, adding an additional layer of security beyond API keys or tokens.

  • Create a client certificate and upload it in API Management > Certificates.
  • Apply the validate-client-certificate policy:
<inbound>
    <validate-client-certificate certificate-thumbprint="ABC123" failed-validation-httpcode="401" failed-validation-error-message="Invalid Certificate" />
</inbound>
  • The certificate must match the thumbprint to allow access.

*Client certificate authentication enhances API security, especially for internal or highly sensitive APIs.

50. Implement API Threat Detection with Azure Defender for APIs

Azure Defender for APIs helps detect and mitigate threats specific to APIs, such as common API attacks, unusual access patterns, and vulnerabilities.

  • In the Azure Portal, navigate to API Management > Defender for APIs > Enable Defender for APIs.
  • Configure alerts and monitoring for security incidents through Azure Security Center.

*Threat detection is critical to securing public APIs, especially those handling sensitive data.

51. Perform Quota Management Using Quota and Rate Limiting Policies

Quota management ensures that API consumers do not exceed usage limits, protecting your API from overuse and abuse.

  • Apply a quota-by-key policy:
<inbound>
    <quota-by-key calls="1000" renewal-period="2629746" counter-key="@(context.Subscription.Id)" />
</inbound>

This policy enforces a quota of 1,000 calls per month for each API subscription.

* Implementing quotas is crucial for managing API usage, particularly for APIs exposed to external consumers.

52. Use Custom Widgets in the Developer Portal for Advanced API Documentation

The Developer Portal can be customised to include interactive elements like custom widgets to enhance the API documentation experience.

  • Use the built-in editor to create custom widgets in the Developer Portal:
    • Navigate to API Management > Developer Portal > Edit.
    • Insert HTML, CSS, or JavaScript-based widgets for enhanced functionality (e.g., adding an interactive API explorer or tutorials).

*While not required, custom widgets can improve the developer experience, making it easier for consumers to integrate with your APIs.

53. Customise the Developer Portal Styles and Branding for API Consumers

To align the Developer Portal with your company’s branding, you can customise the portal’s styles, including colours, fonts, and logos.

  • In the Azure Portal, go to API Management > Developer Portal > Edit.
  • Use the visual editor to apply custom branding, or edit the CSS directly for more advanced customisation.

*Custom branding improves the professional appearance of your API, but it’s not a functional necessity.

54. Extend the Developer Portal by Self-Hosting When Required

In some cases, you may need to self-host the Developer Portal to extend its functionality or integrate with other tools.

  • Clone the Developer Portal source code from the Azure API Management GitHub repository.
  • Deploy the portal to your own web hosting service or infrastructure.
  • Customise the portal beyond the capabilities of the built-in editor.

*Self-hosting is useful when you need complete control over the Developer Portal’s features, but it’s not always necessary.

55. Enable Azure Active Directory B2C for API Consumer Identity Management

Azure Active Directory B2C (Business to Consumer) allows you to manage identity and access for external API consumers, enabling self-service registration, login, and account management.

  • Set up an Azure AD B2C tenant and configure user flows (e.g., sign-up, sign-in).
  • In API Management, navigate to OAuth 2.0 + OpenID Connect > Add Identity Provider and configure B2C as the identity provider for API access.

*For APIs exposed to a large number of external consumers, using Azure AD B2C simplifies user identity management.

56. Manage API Consumer Analytics via the Developer Portal

API consumers can view analytics about their API usage, such as the number of calls made, response times, and quota limits.

  • In the Developer Portal, enable the Analytics section by navigating to Developer Portal > Content > Analytics.
  • API consumers can view their API usage through a dashboard, including quota consumption and performance metrics.

*Providing API analytics can improve transparency for API consumers, helping them optimise their API usage, but it’s not mandatory.

57. Set Up Subscription Approval Workflows for API Products

When a consumer requests access to an API product, you can configure a subscription approval workflow to manually or automatically approve subscription requests.

  • In API Management, go to API Management > Products > Add Product.
  • Enable the Requires Approval option for the product.
  • Configure the subscription approval process, either manual or automatic.

*For sensitive APIs or those requiring specific access control, setting up an approval workflow ensures the right consumers get access.

58. Use Subscription Keys to Manage Protected API Access

Subscription keys provide an easy way to manage access control for APIs, requiring users to pass the key in requests to access protected endpoints.

  • Generate a subscription key by navigating to API Management > Subscriptions > Add Subscription.
  • Consumers must pass the key in the request header as Ocp-Apim-Subscription-Key to access the API:
curl -H "Ocp-Apim-Subscription-Key: <subscription-key>" https://api.example.com/resource

*Subscription keys are a fundamental part of API access control and should be used in most cases.

59. Provide Interactive API Testing via the Developer Portal

Allow API consumers to test API requests directly from the Developer Portal using an interactive testing interface like Swagger UI.

  • Enable interactive testing in the Developer Portal by configuring the API documentation.
  • Consumers can use the portal to send requests to APIs, with real-time feedback on success or failure.

*Interactive testing improves developer experience by allowing API consumers to quickly test integrations without needing external tools.

60. Export APIs to Power Platform for Use by Citizen Developers

You can export APIs managed by Azure API Management to Power Platform (Power Apps, Power Automate) for use by non-developer teams, enabling easy API consumption.

  • In the Azure Portal, go to API Management > APIs > Export > Power Platform.
  • Power Platform connectors are generated from the API, enabling low-code/no-code users to integrate with the API in Power Apps or Power Automate.

*This is a useful feature if your organisation uses Power Platform, but it’s not mandatory for all API implementations.

61. Consider the v2 Tiers for Simplified Networking and Faster Scaling

The v2 tiers (Developer v2, Premium v2, Standard v2) offer simplified networking, faster scaling, and improved performance for API Management instances.

  • When creating a new API Management instance, choose the v2 version in the tier selection.
  • If upgrading from a v1 tier, plan the migration to a v2 tier to benefit from faster scaling and improved performance.

*While not mandatory, upgrading to v2 tiers provides significant performance improvements for API Management.

62. Use OpenTelemetry for Distributed Tracing in API Management

OpenTelemetry provides distributed tracing, allowing you to monitor request flows across multiple services in a microservices-based architecture.

  • Enable OpenTelemetry tracing by integrating API Management with Application Insights or other observability tools.
  • Configure the API to generate trace spans and propagate trace context through your services for full observability of API traffic.

*Distributed tracing is highly beneficial for complex, microservices-based APIs, but it may not be necessary for simpler APIs.

64. Implement Request and Response Validation Using Policies

Request and response validation ensures that the API only processes well-formed and authorised data. Validation can prevent unnecessary load on backend services by stopping invalid requests before they reach the backend.

Request Validation: Use the validate-content policy to enforce schema validation on incoming requests. This ensures that incoming data conforms to expected formats before it reaches the backend. Example: Validate that a JSON request body contains required fields (name and email):

<inbound> <base /> <validate-content content-type="application/json"> <json-schema> { "type": "object", "properties": { "name": { "type": "string" }, "email": { "type": "string", "format": "email" } }, "required": ["name", "email"] } </json-schema> </validate-content> </inbound>

This ensures that the API will reject any request that does not provide the necessary fields, returning a 400 Bad Request response with a validation error message.

Response Validation: You can apply similar validation on the API response before it is sent to the client. Use the validate-content policy in the outbound section to ensure that responses meet specific criteria. Example: Ensure the response contains a userId field:

<outbound> <base /> <validate-content content-type="application/json"> <json-schema> { "type": "object", "properties": { "userId": { "type": "string" } }, "required": ["userId"] } </json-schema> </validate-content> </outbound>

HTTP Status Code Validation: You can also validate HTTP status codes in the response to ensure the API behaves as expected. Use the check-header policy to verify that a response returns the correct StatusCode.Example: Validate that the status code is 200 OK:

<outbound> <check-status-code expected-status-code="200" failed-check-httpcode="500" failed-check-error-message="Unexpected Response Status" /> </outbound>

*Request and response validation is crucial for ensuring that only correct and authorised data enters and exits your API, protecting backend services and improving reliability.

65. Use Policy Fragments to Modularise Policy Configuration

Policy fragments allow you to reuse common policies across multiple APIs, reducing redundancy and simplifying management. This is especially useful for large-scale API deployments where certain policies (e.g., rate limiting, security) are applied to multiple endpoints.

Create a Policy Fragment: In the Azure Portal, navigate to API Management > Policy Fragments > Create Fragment. Define common logic here, such as authentication checks or logging rules. Example: Create a reusable logging policy:

<log-to-eventhub log-level="Information" eventhub-namespace="myEventHubNamespace" eventhub-name="apilogs"> @("Request ID: " + context.Request.Id + " User ID: " + context.User.Id) </log-to-eventhub>

Apply the Fragment to Multiple APIs: Once the policy fragment is created, you can apply it across various APIs or operations. Use the include-fragment tag to reuse the fragment in other policies.Example: Include the logging fragment in multiple APIs:

<inbound> <include-fragment fragment-id="logging-fragment" /> </inbound>

Versioning and Updates: Policy fragments can be updated centrally, and all APIs using the fragment will inherit the updated logic. This is particularly useful for making global changes like adding new security checks or updating logging practices.

*Using policy fragments simplifies policy management, particularly in large deployments, though not all projects will require them.

66. Implement CI/CD Pipelines for API Management Configurations

Automating the deployment of API Management configurations using Continuous Integration/Continuous Deployment (CI/CD) pipelines ensures that changes are deployed reliably and consistently across environments.

Source Control: Store API Management configurations (policies, APIs, products) in source control, such as Git or Azure Repos. Use ARM templates or Azure API Management DevOps Resource Kit to manage API configurations as code. Example: Define API configurations in an ARM template:

{ "type": "Microsoft.ApiManagement/service/apis", "name": "[concat(parameters('apimServiceName'), '/myAPI')]", "apiVersion": "2020-12-01", "properties": { "displayName": "My API", "serviceUrl": "https://backend.example.com", "path": "myapi", "protocols": ["https"] } }

Automated Deployment: Set up a CI/CD pipeline using Azure DevOps or GitHub Actions to deploy API configurations from source control to your API Management service.Example: Using Azure DevOps pipeline YAML:

trigger: branches: include: - main jobs: - job: Deploy_APIM pool: vmImage: 'ubuntu-latest' steps: - task: AzureResourceManagerTemplateDeployment@3 inputs: azureSubscription: '<subscription_id>' resourceGroupName: '<resource_group_name>' deploymentScope: 'Resource Group' location: 'East US' templateLocation: 'Linked artifact' csmFile: '$(System.DefaultWorkingDirectory)/templates/apim-template.json'

Version Control: Use version control practices for API configurations, such as branching, pull requests, and automated testing, to ensure stability and consistency across environments (e.g., dev, staging, production).

*CI/CD pipelines ensure smooth, repeatable, and auditable deployments, reducing the risk of manual errors in production environments.

67. Use Git for Configuration Management in API Management

Azure API Management allows integration with Git, enabling you to manage API configurations as code and version them in Git repositories. This ensures that API policies, definitions, and settings are stored and tracked as part of your source control system.

Enable Git Access in API Management: In the Azure Portal, go to API Management > Repository and enable Git Access. Clone the repository to your local machine:

git clone https://<apim_instance>.scm.azure-api.net/apim-repository

Manage API Configurations: Once you’ve cloned the repository, you can manage API configurations (such as APIs, products, policies, and named values) locally in XML files. Make changes directly to these files and push them back to the repository. Example: Add a new API by modifying the apis folder in the Git repository:

<api xmlns="http://schemas.microsoft.com/..." name="my-api" serviceUrl="https://my-backend-service.com" protocols="https"> <!-- Define operations, policies, etc. --> </api>

Deploy Changes: Push the changes back to the Git repository, which automatically updates the API Management instance.

git add . git commit -m "Added new API configuration" git push origin main

Use Git Workflows: You can use Git workflows, such as branching and pull requests, to manage the API development lifecycle, ensuring that changes are reviewed and tested before being deployed to production.

*Using Git for configuration management allows versioning, tracking, and collaborative development, ensuring consistency and accountability in API management.

68. Configure Autoscaling Based on Azure Monitor Metrics

API Management services can be autoscaled dynamically based on real-time metrics such as CPU usage or request volume. Autoscaling ensures that the service automatically adjusts its resources to handle traffic spikes while maintaining performance.

Enable Autoscale: In the Azure Portal, navigate to API Management > Scale and enable autoscaling. Define rules based on metrics such as CPU percentage, number of requests, or memory usage.

Define Autoscaling Rules: Use Azure Monitor to track key metrics and set up autoscaling thresholds. For example, configure a rule to scale up when CPU usage exceeds 80%:

az monitor autoscale create --resource-group myResourceGroup --name autoscale-apim \ --resource apim-instance --min-count 2 --max-count 10 --count 3

Custom Autoscaling Metrics: You can also create custom autoscaling metrics in Azure Monitor to trigger scaling based on specific conditions, such as request response time or request rate.Example: Scale up API Management when the request rate exceeds 1000 requests per second:

az monitor autoscale rule create --resource-group myResourceGroup --autoscale-name myAutoScale \ --scale out --condition "Requests > 1000 count 1m"

Testing Autoscale: Test the autoscaling rules by generating load through a performance testing tool like Apache JMeter or Azure Load Testing.

*Autoscaling is essential for production APIs to ensure they can handle sudden spikes in traffic without manual intervention.

69. Use Multiple Workspaces for Decentralised API Development

In larger organisations or projects, using separate workspaces allows teams to work on different parts of the API Management service without affecting each other. This decentralised model enables teams to collaborate more effectively by isolating their API development environments.

Workspace Creation: Azure API Management doesn’t natively support separate workspaces like some DevOps tools, but you can achieve similar functionality by creating multiple API Management instances, or by segmenting API definitions into different resource groups or subscriptions within Azure.Example: Split development environments by resource group for better isolation:

az group create --name DevelopmentWorkspace --location eastus az apim create --name DevAPIMInstance --resource-group DevelopmentWorkspace --location eastus

Using Subscriptions for Isolation: You can further use Azure API Management subscriptions to isolate environments. For example, one team may work on APIs within a development subscription, while another works in staging or production. Example: Create separate product subscriptions for different workspaces:

az apim product create --resource-group myResourceGroup --service-name myAPIM --product-id DevWorkspace --display-name "Development Workspace" --subscription-required true

Promote APIs Across Workspaces: Once a team has completed their API development in one workspace, you can promote the APIs to the next environment (e.g., staging or production) using CI/CD pipelines.

*Useful in large-scale projects, but not required for all environments. It’s more applicable for organisations with separate teams or projects that require isolation.

70. Apply Request Throttling Policies to Manage Traffic Spikes

Request throttling ensures that API endpoints are not overwhelmed by a sudden influx of traffic. Throttling is especially important for APIs that are exposed to the public or APIs with limited backend capacity.

Rate Limiting with Policy: Use the rate-limit-by-key policy to throttle requests based on the consumer’s subscription key, IP address, or user ID. This prevents a single client from overwhelming the API by limiting how many requests they can make in a given time frame.Example: Limit each client to 500 requests per minute:

<inbound> <rate-limit-by-key calls="500" renewal-period="60" counter-key="@(context.Subscription.Key)" /> </inbound>

Throttle by IP Address: In some cases, you may want to apply throttling based on the client’s IP address instead of their API subscription. Use the client’s IP as the counter-key:

<inbound> <rate-limit-by-key calls="100" renewal-period="60" counter-key="@(context.Request.IpAddress)" /> </inbound>

Global Throttling: To enforce limits globally across the entire API, apply the throttling policy at the global policy level. This ensures that the limits apply to all requests, regardless of the specific API endpoint. Example: Throttle requests globally to 10,000 calls per hour:

<inbound> <rate-limit calls="10000" renewal-period="3600" /> </inbound>

Error Handling for Throttling: When throttling limits are reached, you can return custom error messages using the set-body policy:

<on-error> <set-status code="429" reason="Too Many Requests" /> <set-body>{"error": "Rate limit exceeded. Try again in 60 seconds."}</set-body> </on-error>

*Throttling is necessary to protect the API from abuse and to ensure that backend services remain available during high-traffic periods.

71. Implement API Revisions for Safe Rollout of Changes

API revisions allow you to safely introduce changes to an API without disrupting existing consumers. Revisions provide a way to track different versions of an API within the same version number, allowing for updates and rollbacks without changing the version.

Create a Revision: In the Azure Portal, navigate to API Management > APIs > Revisions > Create Revision. A new revision can be created without breaking existing clients, allowing you to test new features or changes.Example: Add a new operation to an existing API in a new revision:

<operation name="GetOrderStatus" method="GET" urlTemplate="/orders/{id}/status"> <request /> <response statusCode="200"> <representation mediaType="application/json" /> </response> </operation>

Test Revisions Before Publishing: You can test revisions in a non-public state. This allows your team to fully verify the changes in a development or staging environment before exposing the new revision to production.

Publish or Rollback Revisions: Once a revision is tested, you can publish it, making it live for all consumers. If there’s an issue, you can quickly roll back to the previous revision:

az apim api release create --api-id myAPI --revision 2 --resource-group myResourceGroup --service-name myAPIM

Version vs. Revision: Remember, revisions are different from API versions. Revisions allow you to iterate within the same version, while versions (e.g., v1, v2) denote breaking changes that may require clients to upgrade.

*Using revisions is highly recommended for safely managing changes without disrupting users, but not strictly necessary for smaller APIs with minimal changes.

72. Use API Versions to Manage Breaking Changes

API versions allow you to introduce breaking changes without disrupting existing clients. By supporting multiple versions of an API, you give clients time to upgrade to the latest version while continuing to support older versions.

Versioning by Path: The most common way to version APIs is by including the version in the path. For example, /v1/orders and /v2/orders can point to different implementations of the same API.

<api name="OrdersAPI" revision="1" path="v1/orders" serviceUrl="https://backend-v1.example.com"> <!-- Operations for v1 --> </api> <api name="OrdersAPI" revision="1" path="v2/orders" serviceUrl="https://backend-v2.example.com"> <!-- Operations for v2 --> </api>

Versioning by Query String: Alternatively, you can version your APIs by adding a version parameter in the query string, such as ?version=1.0. Use the rewrite-uri policy to route requests to the correct backend based on the query string value:

<inbound> <rewrite-uri template="/v@(context.Request.QueryString.GetValueOrDefault("version", "1.0")){urlPath}" /> </inbound>

Deprecating Old Versions: To deprecate an old version, you can return a custom warning message and specify an end-of-life date for the version. Use the set-header policy to include the deprecation notice:

<inbound> <set-header name="Deprecation" exists-action="override"> <value>This API version will be deprecated on 2024-01-01. Please upgrade to v2.</value> </set-header> </inbound>

Documenting API Versions: Ensure that each version of the API is clearly documented in the Developer Portal, including what’s new or different in each version and any migration steps for clients.

*Versioning is critical for managing breaking changes in APIs, allowing clients to upgrade at their own pace while ensuring backward compatibility.

73. Set Up Multi-Region Deployments for Enhanced Availability

Multi-region deployments ensure that your API Management service is available across multiple Azure regions, improving availability and performance by serving clients from the region closest to them.

Deploy to Multiple Regions: In the Azure Portal, navigate to API Management > Locations and add additional regions to your existing API Management instance. This automatically replicates your APIs across regions.Example: Add a secondary region for disaster recovery:

az apim create --name myAPIM --resource-group myResourceGroup --location eastus --additional-locations location=westus,capacity=1

Use Traffic Routing: Use Azure Traffic Manager or Azure Front Door to route requests to the closest API Management instance based on the client’s geographical location or the health of the region.

az network traffic-manager profile create --resource-group myResourceGroup --name myTrafficManager --routing-method Performance

Monitor Regional Health: You can monitor the health and availability of each region in Azure Monitor or Azure Application Insights. If one region becomes unhealthy, traffic is automatically routed to a healthy region.

Disaster Recovery and Failover: Multi-region deployments provide built-in disaster recovery by ensuring that if one region goes down, API traffic can fail over to another region seamlessly.

*For mission-critical APIs, multi-region deployments are necessary to ensure high availability, resilience, and low latency for global users.

74. Inject API Management into a Virtual Network (VNet) for Secure, Private API Access

To securely connect your API Management instance to backend services running inside a private Azure Virtual Network (VNet), you can deploy API Management in Internal VNet mode. This allows APIs to securely interact with backend services that are not exposed to the public internet.

Configure VNet Integration: In the Azure Portal, go to API Management > Virtual Network and enable Internal VNet mode. Select the desired Virtual Network and subnet to host the API Management instance.Example: Attach API Management to a VNet:

az network vnet create --name myVNet --resource-group myResourceGroup --subnet-name apimSubnet az apim create --name myAPIM --resource-group myResourceGroup --vnet myVNet --subnet apimSubnet

Private Endpoints: Use Private Link to expose API Management via a private IP address. This ensures that all API traffic remains within your secure Azure network.

Network Security Groups (NSGs): Apply Network Security Groups to control inbound and outbound traffic within the VNet. Restrict access to only trusted IP ranges or specific backend services.

VNet Peering: If your API Management instance and backend services are in different VNets, use VNet Peering to connect them securely without exposing the services to the internet.

*For securing internal APIs or backend services that should not be publicly accessible, VNet integration is essential.

75. Integrate API Management with Azure Private Endpoints for Security

Private Endpoints enable you to securely expose your APIs over a private IP address within your Virtual Network, ensuring that API traffic is not exposed to the public internet.

Set Up a Private Endpoint: In the Azure Portal, navigate to API Management > Private Endpoints > Add Private Endpoint. This creates a private IP address within your VNet that clients can use to access the APIs securely.Example: Create a private endpoint using Azure CLI:

az network private-endpoint create --name apimPrivateEndpoint --vnet-name myVNet --subnet mySubnet --group-id apimService

DNS Configuration: Configure the Azure Private DNS zone to resolve the API Management service’s domain name to the private IP address:

az network private-dns zone create --resource-group myResourceGroup --name privatelink.api.azure.com

Secure Backend Connections: Using private endpoints ensures that the API gateway securely connects to backend services through a private network, eliminating the need for public IP addresses.

*Private endpoints are crucial for securing API traffic in enterprise environments, where public exposure should be minimized or eliminated.

76. Implement Secure Backend Connectivity with Azure Private Link

To secure API Management’s connectivity to backend services, you can use Azure Private Link. Private Link allows API Management to securely communicate with backend services over a private IP address, eliminating the need to expose the backend services to the public internet. This is ideal for services that handle sensitive data or must comply with strict security standards.

In the Azure Portal, navigate to your API Management service and select Private Link. Create a private endpoint for the backend service by connecting it to a Virtual Network (VNet). Configure DNS settings to resolve the API Management service’s domain name to the private IP address generated by the private link.

Example of creating a private endpoint with Azure CLI:

az network private-endpoint create --name apimPrivateEndpoint --vnet-name myVNet --subnet mySubnet --group-id apimService --resource-group myResourceGroup

This ensures that all traffic between API Management and backend services is routed over a secure private network, avoiding exposure to the public internet. Use Network Security Groups (NSGs) to further control traffic to and from the private endpoint, restricting access to only trusted IP addresses.

*Private connectivity is essential for securing APIs and backend services, ensuring compliance with security requirements by preventing public exposure of sensitive services.

77. Utilise Backend Health Probes for High Availability and Monitoring

Health probes allow you to continuously monitor the health of backend services connected to API Management. This ensures that API Management only forwards traffic to healthy backends, improving overall availability and reliability. Health probes are particularly useful for multi-region deployments or services that require dynamic scaling.

You can configure health probes through Azure Traffic Manager or Application Gateway, which will automatically detect if a backend service becomes unresponsive and reroute traffic to a healthy instance. To monitor the health of your APIs, use Azure Monitor integrated with API Management to track the status of backend services and receive alerts when a service becomes unavailable.

Example of creating a health probe in Azure CLI:

az network application-gateway probe create --resource-group myResourceGroup --gateway-name myAppGateway --name myHealthProbe --protocol Http --host myBackendHost --path /healthcheck

The health probe continuously checks the /healthcheck endpoint of your backend service. If the service becomes unresponsive, API Management will stop forwarding traffic to it and trigger an alert.

*Ensuring backend health is critical for maintaining the reliability and availability of APIs, especially in environments where multiple services or regions are involved.

78. Implement Token Caching for Enhanced Authentication Performance

Token caching helps improve the performance of authentication mechanisms by reducing the need to validate tokens on every request. By caching valid tokens for a specified period, you can reduce the overhead of constantly checking tokens against identity providers such as Azure AD or OAuth2 servers.

In Azure API Management, use the cache-lookup and cache-store policies to cache validated tokens after their first successful authentication. For example, when a JWT token is validated successfully, you can cache the result:

<inbound>
    <cache-lookup vary-by-developer="true" vary-by-developer-groups="false" />
</inbound>
<backend>
    <validate-jwt header-name="Authorization" failed-validation-httpcode="401" />
</backend>
<outbound>
    <cache-store duration="3600" />
</outbound>

In this example, the validated token is cached for 1 hour (3600 seconds). For subsequent requests within this window, API Management retrieves the token from the cache instead of performing a full validation, improving the API’s performance.

*Token caching is an effective strategy to improve API performance by reducing repeated authentication checks, particularly for APIs with high traffic volumes.

79. Integrate with Third-Party Identity Providers for Cross-Platform Authentication

API Management supports integration with third-party identity providers like Google, Facebook, GitHub, and any OpenID Connect-compliant provider. This allows you to manage authentication for external users without forcing them to create a new identity for your API.

To integrate a third-party identity provider, first register your API with the identity provider’s developer console to obtain client credentials. Then, configure API Management to accept tokens from the provider. For instance, with Google OAuth2, you would set up an OAuth2 authorization server in API Management:

<validate-jwt header-name="Authorization" failed-validation-httpcode="401">
    <openid-config url="https://accounts.google.com/.well-known/openid-configuration" />
    <audiences>
        <audience>your-client-id</audience>
    </audiences>
</validate-jwt>

Once configured, API Management will accept and validate tokens from the third-party identity provider. This allows users to authenticate with their existing accounts on platforms like Google or Facebook when interacting with your APIs.

*Integrating third-party identity providers is useful for APIs that require flexible authentication for external users, particularly in consumer-facing applications.

80. Optimise API Request Payloads with Compression

Large payloads can significantly affect the performance of APIs, especially when transferring large datasets or files. By enabling request and response compression, you can reduce the size of data transferred between clients and backend services, improving both performance and user experience.

Use the set-header policy to enable compression for both requests and responses. For example, to compress responses using Gzip:

<outbound>
    <set-header name="Accept-Encoding" exists-action="override">
        <value>gzip</value>
    </set-header>
</outbound>

Similarly, you can enable compression for incoming requests by specifying the supported encoding types:

<inbound>
    <set-header name="Content-Encoding" exists-action="override">
        <value>gzip, deflate</value>
    </set-header>
</inbound>

This policy instructs the client to compress requests and responses using Gzip or Deflate. It is especially useful for APIs that handle large JSON or XML payloads, as compressed data can drastically reduce bandwidth usage and improve response times.

*Compression is particularly valuable for APIs that deal with large amounts of data or are accessed over slow network connections, improving both performance and efficiency.

81. Use Distributed Tracing for End-to-End API Monitoring

Distributed tracing enables you to track API requests across multiple services, providing a complete view of how requests flow through your system. This is especially useful in microservices architectures, where requests may pass through several services before completing. Distributed tracing allows you to identify bottlenecks, track errors, and measure latency across all services involved in processing an API request.

Integrate API Management with Azure Application Insights to enable distributed tracing. By adding the Request-Id and Correlation-Id headers to each request, you can trace the request across all services that support these headers. For example:

<inbound>
    <set-header name="Request-Id" exists-action="override">
        <value>@(context.Request.Id)</value>
    </set-header>
    <set-header name="Correlation-Id" exists-action="override">
        <value>@(context.Request.Headers.GetValueOrDefault("Correlation-Id", context.Request.Id))</value>
    </set-header>
</inbound>

The Request-Id uniquely identifies the request, while the Correlation-Id helps track the entire chain of requests and responses across multiple services. You can visualize the traces in Application Insights or other monitoring tools that support distributed tracing, helping you pinpoint performance issues or failure points within the system.

*Distributed tracing is critical for monitoring and troubleshooting in complex microservices-based systems, providing visibility into how requests move across different services.

82. Implement Content-Based Routing for Flexible Request Handling

Content-based routing allows you to route API requests to different backend services based on the content of the request, such as the body, headers, or query parameters. This is particularly useful when dealing with APIs that handle multiple types of requests or need to route traffic to different backends based on specific business rules.

Use the choose policy to inspect the request content and route it to the appropriate backend. For example, you can route requests based on a specific field in the request body:

<inbound>
    <choose>
        <when condition="@(context.Request.Body.As<JObject>(preserveContent: true)["customerType"] == "premium")">
            <set-backend-service base-url="https://premium-backend.example.com" />
        </when>
        <otherwise>
            <set-backend-service base-url="https://standard-backend.example.com" />
        </otherwise>
    </choose>
</inbound>

In this policy, if the request body contains "customerType": "premium", the request is routed to the premium backend. Otherwise, it is sent to the standard backend. You can apply similar logic based on headers, query parameters, or other request attributes, providing flexibility in routing decisions without requiring changes to the backend.

*Content-based routing is useful for APIs that need to handle different types of traffic or provide custom routing based on business logic, offering flexibility and scalability in managing complex API workflows.

83. Leverage API Mocking for Early Testing and Development

API mocking allows you to simulate the behavior of an API before the actual backend service is implemented. This is particularly useful during development when the API specification is ready, but the backend logic is still being developed. Azure API Management provides mocking capabilities, enabling you to define static responses for specific API operations. This allows frontend teams or external consumers to start integrating with the API while the backend is still in progress. To enable mocking, define the mock responses in the API Management policies. For example:

<inbound>
    <base />
</inbound>
<backend>
    <mock-response status-code="200">
        <set-body>
            {
                "message": "This is a mock response"
            }
        </set-body>
    </mock-response>
</backend>
<outbound>
    <base />
</outbound>

In this scenario, any request to the API will receive the static mock response defined in the mock-response policy. You can also mock different operations with different responses, allowing you to simulate various API behaviors.

Mocking is a powerful tool to accelerate development, enabling teams to work in parallel and ensure the API contract is being followed without waiting for backend services to be fully implemented.

84. Utilize Named Values for Centralized Configuration Management

Named values in Azure API Management are useful for storing reusable configuration settings, such as API keys, connection strings, or environment-specific URLs. This approach ensures that sensitive information or environment-specific data is managed centrally and can be updated without modifying API policies directly. To implement named values, you can define them in the API Management service and reference them in your policies. For example, a named value can store a backend URL, and it can be injected into the set-backend-service policy:

<inbound>
    <base />
</inbound>
<backend>
    <set-backend-service base-url="@(_context.Variables["BackendUrl"])" />
</backend>
<outbound>
    <base />
</outbound>

In this policy, BackendUrl is a named value that is used dynamically within the API. Named values allow you to change configuration settings centrally in the Azure API Management portal, reducing the risk of errors when updating multiple APIs.

This practice simplifies configuration management and makes it easier to maintain consistency across multiple APIs, particularly in scenarios with multiple environments like development, staging, and production.

88. Implement Quota-Based API Products for Subscription Management

Quota-based API products in Azure API Management allow you to control how much access API consumers have based on their subscription level. For example, you may offer different API tiers, such as a free tier with limited usage and a premium tier with higher limits. You can configure quotas using the quota-by-key policy, which enforces limits on API usage based on the API key or subscription:

<inbound>
    <quota-by-key calls="1000" renewal-period="2629746" counter-key="@(context.Subscription.Key)" />
</inbound>

In this example, the API consumer is limited to 1000 calls per month, after which they will be blocked from making further requests until the quota renews. This type of quota management is essential for subscription-based API products, allowing you to monetize APIs while ensuring that resources are used efficiently.

Quota-based products help manage consumption and ensure that different users or applications have access based on their subscription level, which is crucial for scaling APIs in a sustainable and profitable way.

Tags: APIM best practice
13 Dec 2023
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