Making Safe Non-Breaking API Changes Using Revisions

Azure API Management (APIM) is a powerful tool for creating, publishing, securing, and analyzing APIs. As APIs evolve, it’s crucial to manage changes in a way that doesn’t disrupt existing consumers. Non-breaking changes are modifications that don’t affect the existing functionality of the API, ensuring backward compatibility. Azure APIM provides a feature called Revisions that allows you to safely introduce non-breaking changes to your APIs without impacting current users.

This article will explore how to use revisions in Azure APIM to make non-breaking API changes safely. We’ll cover the following topics:

1. Understanding Non-Breaking API Changes
2. What Are Revisions in Azure APIM?
3. How to Create and Manage Revisions
4. Testing and Validating Revisions
5. Promoting Revisions to Production
6. Best Practices for Using Revisions
7. Common Scenarios for Using Revisions

1. Understanding Non-Breaking API Changes

Non-breaking changes are modifications to an API that don’t disrupt existing clients. These changes are backward-compatible, meaning that clients using the older version of the API continue to function without any issues. Examples of non-breaking changes include:

• Adding new endpoints
• Adding optional query parameters or headers
• Adding new fields to responses
• Deprecating fields or endpoints (without removing them)
• Improving performance or fixing bugs without altering the API contract

Non-breaking changes are essential for maintaining a stable API ecosystem, as they allow you to evolve your API without forcing clients to update their implementations.

2. What Are Revisions in Azure APIM?

Revisions in Azure APIM are a way to version and manage changes to your API without affecting the production version. A revision is a snapshot of your API configuration that you can modify independently. Once you’ve made and tested your changes, you can promote the revision to become the current version of the API.

Key features of revisions include:

• Isolation: Changes made in a revision don’t affect the production API until the revision is promoted.
• Testing: You can test revisions using a unique URL before making them live.
• Rollback: If something goes wrong, you can easily revert to the previous version.
• Multiple Revisions: You can create multiple revisions for an API, allowing you to work on different changes simultaneously.

3. How to Create and Manage Revisions

Step 1: Create a New Revision

1. Navigate to your API in the Azure portal.
2. In the Revisions tab, click + Add Revision.
3. Provide a description for the revision (e.g., “Add new endpoint for user preferences”).
4. Click Create.

Step 2: Make Changes to the Revision

Once the revision is created, you can modify the API configuration. Common changes include:

• Adding new operations (endpoints)
• Modifying existing operations (e.g., adding optional parameters)
• Updating policies (e.g., rate limiting, caching)
• Changing response formats

Step 3: Test the Revision

Each revision has a unique URL that you can use for testing. For example:

https://<your-api>.azure-api.net/<api-name>;rev=<revision-number>

Use tools like Postman or automated tests to validate the changes.

Step 4: Compare Revisions

Azure APIM allows you to compare the current version of the API with the revision. This helps you ensure that only intended changes are made.

4. Testing and Validating Revisions

Testing is a critical step before promoting a revision to production. Here’s how to approach it:

Use the Revision-Specific URL

The revision-specific URL allows you to test changes without affecting the production API. Share this URL with your testing team or use it in automated tests.

Validate Backward Compatibility

Ensure that existing clients continue to work as expected. Test all endpoints and scenarios to confirm that no breaking changes were introduced.

Test New Functionality

Verify that any new endpoints, parameters, or features work as intended.

Monitor Performance

Check for any performance regressions or issues caused by the changes.

5. Promoting Revisions to Production

Once you’ve tested and validated the revision, you can promote it to production. Here’s how:

Step 1: Promote the Revision

1. Navigate to the Revisions tab.
2. Select the revision you want to promote.
3. Click Promote to Current.
4. Confirm the promotion.

Step 2: Notify Stakeholders

Inform your API consumers about the changes, especially if you’ve added new features or deprecated existing ones.

Step 3: Monitor the API

After promoting the revision, monitor the API for any issues. Use Azure APIM’s analytics and logging features to track performance and errors.

6. Best Practices for Using Revisions

To make the most of revisions in Azure APIM, follow these best practices:

Plan Changes Carefully

Before creating a revision, document the changes you intend to make and their impact on existing clients.

Use Descriptive Revision Names

Provide clear and descriptive names for revisions to make it easier to track changes.

Test Thoroughly

Always test revisions in a staging environment before promoting them to production.

Communicate with Consumers

Keep your API consumers informed about upcoming changes, especially if they involve deprecations or new features.

Limit the Number of Revisions

Avoid creating too many revisions, as this can make management difficult. Merge related changes into a single revision when possible.

Use Policies for Backward Compatibility

Leverage Azure APIM policies to handle backward compatibility, such as transforming requests or responses to match older versions.

7. Common Scenarios for Using Revisions

Scenario 1: Adding a New Endpoint

You want to add a new endpoint to your API without affecting existing functionality. Create a revision, add the endpoint, test it, and promote it to production.

Scenario 2: Deprecating an Endpoint

You want to deprecate an endpoint but keep it available for existing clients. Create a revision, mark the endpoint as deprecated, and communicate the change to consumers.

Scenario 3: Modifying Response Formats

You want to add new fields to an API response. Create a revision, update the response schema, and test the changes before promoting them.

Scenario 4: Fixing Bugs

You need to fix a bug in your API. Create a revision, implement the fix, and test it thoroughly before promoting it.