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Test APIs in Production

APIM provides built-in capabilities for testing in production, offering a structured way to manage API changes without disrupting active services. Specifically, revisions enable fine-grained control over API modifications. Each API version can have multiple revisions with the following states:

  • Current: The active revision used for API invocations
  • Online: Available for invocation, but only with explicit revision selection (e.g. /api/v1/resource;rev=2).
  • Offline: Inactive but can be promoted to online or current status

This mechanism allows you to:

  • Modify policies and configurations safely before publishing changes
  • Conduct tests in production without impacting existing API consumers
  • Align versioning with downstream staging services (e.g. AppService and Function App staging slots)

To use revisions, follow these steps:

  1. Choose an existing API group
  2. Create revisions for incremental modifications (e.g. rev 2) and policy updates, and set as Online
  3. Test the revision by invoking the API under test and specifying its revision name in the URL (e.g. /api/v1/resource;rev=2)
  4. Finalize changes and promote a revision to current when ready
  5. Document modifications using changelogs available through APIM

As showed in the next chapter, VS Code can help you in debugging policies via its built-in debugger.

Debug APIM Policies via VS Code​

Visual Studio Code can connect to an online APIM instance, and provide debugging capabilities to developers. For example, it is possible to debug a policy by using breakpoints, from the local environment. In fact, VS Code can:

  • Debug policies with built-in breakpoint support
  • Create API Groups using OpenAPI definitions
  • Associate APIs with products
  • Switch between revisions
  • Execute API tests

To leverage VS Code policy-debugging capabilities:

  1. Install the API Management extension for VS Code
  2. (Optional) Install the REST Client extension for VS Code: it automatically manage the subscription key in request header (Ocp-Apim-Debug)
  3. Run the API Management extension and select the APIM instance
  4. Navigate through the desired API group and operation to debug
  5. Right click and select Start Policy Debugging
  6. Set a breakpoint in policy body
  7. Invoke the API under test

APIM Policy in Debug Mode