Traffic Mirroring (Shadow Traffic)¶

Traffic mirroring allows you to send a copy of live traffic to a secondary backend for testing, debugging, or observability purposes without affecting the original request flow.

Overview¶

When traffic mirroring is enabled on a route rule, NovaEdge:

Forwards the original request to the primary backend as normal
Asynchronously clones the request and sends it to the mirror backend (fire-and-forget)
Discards the mirror response — the original request is never affected by the mirror

Mirror requests include an X-Mirror: true header so the mirror backend can distinguish them from real traffic.

Configuration¶

Per-Route Mirror (CRD)¶

Add a mirror block to any route rule in a ProxyRoute:

apiVersion: novaedge.io/v1alpha1
kind: ProxyRoute
metadata:
  name: api-route
spec:
  hostnames:
    - api.example.com
  rules:
    - matches:
        - path:
            type: PathPrefix
            value: /api/v1
      backendRefs:
        - name: api-backend
          weight: 1
      mirror:
        backendRef:
          name: api-shadow-backend
        percentage: 50  # Mirror 50% of requests

Per-Filter Mirror¶

You can also use the RequestMirror filter type in route filters:

filters:
  - type: RequestMirror
    mirrorBackend:
      name: shadow-backend
    mirrorPercent: 100

Standalone Mode¶

In standalone YAML configuration:

routes:
  - name: api-route
    match:
      hostnames:
        - api.example.com
      path:
        type: PathPrefix
        value: /api
    backends:
      - name: api-backend
    mirror:
      backend: shadow-backend
      percentage: 25

Configuration Options¶

Field	Type	Default	Description
`backendRef.name`	string	required	Name of the ProxyBackend to mirror to
`backendRef.namespace`	string	route namespace	Namespace of the mirror backend
`percentage`	int (0-100)	100	Percentage of requests to mirror

Behavior¶

Asynchronous: Mirror requests run in a separate goroutine and never block the original request
Fire-and-forget: Mirror responses are discarded; errors are logged but do not affect the client
Body cloning: Request bodies are buffered and sent to both primary and mirror backends
Context respect: If the original request's context is cancelled before the mirror starts, the mirror is skipped
Timeout: Mirror requests have a 10-second timeout to prevent goroutine leaks

Metrics¶

Metric	Type	Description
`novaedge_mirror_requests_total`	Counter	Total mirrored requests sent
`novaedge_mirror_errors_total`	Counter	Total mirror request errors
`novaedge_mirror_latency_seconds`	Histogram	Mirror request latency

Use Cases¶

Shadow testing: Route production traffic to a new service version to verify behavior
Performance benchmarking: Compare response times between current and new backends
Debug logging: Send traffic copies to a debug service that logs request details
Data validation: Verify a new backend produces equivalent responses

Best Practices¶

Start with a low mirror percentage (e.g., 10%) and increase gradually
Ensure the mirror backend can handle the additional load
Monitor mirror error rates to detect backend issues
Use the X-Mirror: true header in mirror backends to skip side effects (e.g., database writes)