# Exhaustive HTTPRoute reference (gateway.networking.k8s.io/v1).
# Attaches to a Gateway listener via parentRefs and routes HTTP(S) by
# hostname + path/method/headers/query. Rules are evaluated in order; the
# first matching rule wins.
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: app
  namespace: example
  labels:
    app: app
spec:
  parentRefs:
    # Every entry picks one listener to bind to. Omit sectionName/port to
    # attach to ALL listeners of the Gateway (common for simple setups).
    - name: example
      # namespace: Gateway's namespace. Omit when same-namespace (the norm;
      # cross-namespace needs the Gateway to allow it).
      # namespace: example
      # kind/group: default Gateway / gateway.networking.k8s.io. Set
      # explicitly only for non-Gateway parents (mesh service parents).
      kind: Gateway
      group: gateway.networking.k8s.io
      # sectionName: the listener name from the Gateway (http/https/...).
      sectionName: https
      # port: narrow further to one listener port. RARE when sectionName is
      # already set.
      port: 443
  # hostnames: which Host headers this Route serves. Must intersect the
  # listener hostname; otherwise the Route is rejected as incompatible.
  # Omit to match every hostname on the listener.
  hostnames:
    - app.example.com
    - www.example.com
  rules:
    # Rule 1: API traffic with header manipulation and canary split.
    - matches:
        # All conditions inside one match are ANDed; several matches in the
        # list are ORed.
        - path:
            # type: Exact (one URL), PathPrefix (subtree), RegularExpression.
            type: PathPrefix
            value: /api
          method: POST
          headers:
            # type: Exact or RegularExpression. Names are case-insensitive
            # per HTTP spec; values are case-sensitive.
            - type: Exact
              name: X-Api-Version
              value: v2
          queryParams:
            # Match on ?debug=true style parameters.
            - type: Exact
              name: debug
              value: "true"
      filters:
        # Filters run in order and transform the request/response.
        - type: RequestHeaderModifier
          requestHeaderModifier:
            # add: append even if present (duplicates allowed). set:
            # overwrite-or-add. remove: delete by name.
            add:
              - name: X-Gateway
                value: example
            set:
              - name: X-Forwarded-Proto
                value: https
            remove:
              - X-Internal-Token
        - type: ResponseHeaderModifier
          responseHeaderModifier:
            set:
              - name: X-Frame-Options
                value: DENY
            remove:
              - Server
        # backendRefs below carry per-backend filters too; rule-level filters
        # apply to every backend of this rule.
      backendRefs:
        - name: app-service
          # port: the Service port (number). Required - unlike backendRef in
          # Ingress, there is no default.
          port: 80
          # group/kind: default Service / core (""). Other kinds (e.g. a
          # ServiceImport for multi-cluster) set kind + group explicitly.
          kind: Service
          group: ""
          # weight: traffic share. 90/10 below = canary: 90% stable, 10% new.
          weight: 90
          filters:
            # Per-backend filter: only this backend's requests get it.
            - type: RequestHeaderModifier
              requestHeaderModifier:
                set:
                  - name: X-Backend
                    value: stable
        - name: app-canary-service
          port: 80
          weight: 10
          filters:
            - type: RequestHeaderModifier
              requestHeaderModifier:
                set:
                  - name: X-Backend
                    value: canary
      # timeouts: per-attempt deadlines. request = whole gateway-to-client
      # exchange; backendRequest = single backend try.
      timeouts:
        request: 30s
        backendRequest: 10s
      # sessionPersistence: stick a client to one backend (cookie-based).
      # Type Cookie or Header; absoluteTimeout caps the stickiness.
      sessionPersistence:
        sessionName: route-session
        type: Cookie
        absoluteTimeout: 1h
        cookieConfig:
          lifetimeType: Session
    # Rule 2: redirect old path to a new URL.
    - matches:
        - path:
            type: PathPrefix
            value: /old-docs
      filters:
        - type: RequestRedirect
          requestRedirect:
            # Any combination: scheme/host/port/path/statusCode. Unset fields
            # keep the original value.
            scheme: https
            hostname: docs.example.com
            path:
              # type: ReplaceFullPath or ReplacePrefixMatch (rewrite the
              # matched prefix, keep the remainder).
              type: ReplacePrefixMatch
              replacePrefixMatch: /docs
            port: 443
            # statusCode: 301 (permanent) or 302 (temporary).
            statusCode: 301
    # Rule 3: rewrite the URL but still proxy (client sees no redirect).
    - matches:
        - path:
            type: PathPrefix
            value: /shop
      filters:
        - type: URLRewrite
          urlRewrite:
            path:
              type: ReplacePrefixMatch
              replacePrefixMatch: /store
            # hostname: also rewrite the Host header sent upstream.
            # hostname: store-internal.example.com
      backendRefs:
        - name: app-service
          port: 80
    # Rule 4: mirror (shadow) traffic to a second backend for testing.
    # The mirror gets a copy; its response is discarded.
    - matches:
        - path:
            type: Exact
            value: /checkout
      filters:
        - type: RequestMirror
          requestMirror:
            backendRef:
              name: app-shadow-service
              port: 80
      backendRefs:
        - name: app-service
          port: 80
    # Rule 5: delegate to an implementation-specific filter (auth plugin,
    # rate limit, wasm). The controller documents the group/kind it honors.
    # - filters:
    #     - type: ExtensionRef
    #       extensionRef:
    #         group: example.com
    #         kind: AuthPolicy
    #         name: app-auth
    # Catch-all rule (no matches): everything not matched above lands here.
    - backendRefs:
        - name: app-service
          port: 80