Azure API Management版本化API中rewrite-uri策略失效问题

This is a super common pitfall when versioning APIs in APIM, and the root cause boils down to the order of request processing in Azure API Management—it first matches your request to the correct API version and operation before executing any inbound policies like rewrite-uri. Let’s break down exactly what happened:

What Went Wrong Initially #

When you set up the v2 version:

1. You created a Header-based version (api-version: v2) to distinguish it from v1.
2. You kept the frontend URL of the get-all-goods operation in v2 as GET /api/store/goods (identical to v1).
3. You added a rewrite-uri policy in the v2 operation’s inbound section to rewrite the path to /api/v2/store/goods.

The 404 error with the trace message Unable to identify Api or Operation for this request tells us APIM never even got to run your rewrite-uri policy. Here’s why:
APIM’s request flow follows this strict order:

• First, it uses the api-version header to match the v2 API version.
• Next, it looks for an operation in the v2 API that matches the incoming request’s HTTP method and URL path (GET /api/store/goods).
• Only if it finds a matching operation does it execute the operation’s inbound policies.
• If no operation matches, it returns a 404 immediately.

In your initial setup, APIM couldn’t find a matching operation in the v2 API for /api/store/goods—either the operation wasn’t properly added to the v2 version, or there was a subtle configuration mismatch (like a typo in the path or HTTP method). Without a matched operation, the rewrite-uri policy never ran.

Why Changing the Frontend URL Fixed It #

When you updated the v2 operation’s frontend URL to GET /api/v2/store/goods and removed the rewrite-uri policy:

• Your incoming request to https://bk-xxx.azure-api.net/api/v2/store/goods (with api-version: v2) now perfectly matched the v2 operation’s method and path.
• APIM successfully identified the operation, skipped the unnecessary rewrite-uri policy, and forwarded the request to the backend by appending the matched path to your Web Service URL (https://bk.my.com/ + /api/v2/store/goods), which hit the correct v2 backend API.

How to Make rewrite-uri Work for the Original Frontend Path #

If you want to keep the frontend path as /api/store/goods for v2 (matching v1) and use rewrite-uri to map to the v2 backend, ensure these steps are done correctly:

• Add the operation to v2: Make sure the get-all-goods operation with frontend URL GET /api/store/goods exists in the v2 API version (not just v1).
• Apply the policy at the operation level: The rewrite-uri policy must be attached to the v2 operation (not the API-level policy), so it runs only after APIM matches the request to that operation.
• Verify version configuration: Double-check that the Header-based version is set up with api-version as the header name and v2 as the value, linked correctly to the v2 API.

Once these are in place, APIM will match the request to the v2 operation, run the rewrite-uri policy to adjust the path to /api/v2/store/goods, and forward it to the backend successfully.

内容的提问来源于stack exchange，提问作者Redman