Module mirror 

Traffic mirroring / shadowing middleware.

Sends a copy of traffic to a secondary backend (fire-and-forget, response discarded). Useful for testing new backend versions, benchmarking, or audit recording.

Configuration

[[backends]]
name = "api"
transport = "http"
url = "http://api.internal:8080"

[[backends]]
name = "api-v2"
transport = "http"
url = "http://api-v2.internal:8080"
mirror_of = "api"        # mirror traffic from "api" backend
mirror_percent = 10      # mirror 10% of requests

How it works

1. Request arrives targeting api/search
2. Primary response is returned from the api backend as normal
3. A copy of the request is rewritten to api-v2/search and sent fire-and-forget to the api-v2 backend
4. The mirror response is discarded; errors are logged but don’t affect the primary response

Structs

MirrorLayer

Tower layer that produces a MirrorService.

MirrorService

Traffic mirroring middleware.