MeshTCPRoute

The MeshTCPRoute policy allows you to alter and redirect TCP requests depending on where the request is coming from and where it’s going to.

TargetRef support matrix

For more information, see the matching docs.

Configuration

Unlike other outbound policies, MeshTCPRoute doesn’t contain default directly in the to array. The default section is nested inside rules, so the policy structure looks like the following:

spec:
  targetRef: # top-level targetRef selects a group of proxies to configure
    kind: Mesh|MeshSubset|MeshService|MeshServiceSubset 
  to:
    - targetRef: # targetRef selects a destination (outbound listener)
        kind: MeshService
        name: backend
      rules:
        - default: # configuration applied for the matched TCP traffic
            backendRefs: [...]

Default configuration

The following describes the default configuration settings of the MeshTCPRoute policy:

• backendRefs: (Optional) List of destinations for the request to be redirected to
  • kind: One of MeshService, MeshServiceSubset
  • name: The service name
  • tags: Service tags. These must be specified if the kind is MeshServiceSubset.
  • weight: When a request matches the route, the choice of an upstream cluster is determined by its weight. Total weight is a sum of all weights in the backendRefs list.

Gateways

In order to route TCP traffic for a MeshGateway, you need to target the MeshGateway in spec.targetRef and set spec.to[].targetRef.kind: Mesh.

Interactions with MeshHTTPRoute

MeshHTTPRoute takes priority over MeshTCPRoute when both are defined for the same service, and the matching MeshTCPRoute is ignored.

Interactions with TrafficRoute

MeshTCPRoute takes priority over TrafficRoute when a proxy is targeted by both policies.

All legacy policies like Retry, TrafficLog, Timeout etc. only match on routes defined by TrafficRoute. All new recommended policies like MeshRetry, MeshAccessLog, MeshTimeout etc. match on routes defined by MeshTCPRoute and TrafficRoute.

If you don’t use legacy policies, it’s recommended to remove any existing TrafficRoute. Otherwise, it’s recommended to migrate to new policies and then removing TrafficRoute.

Examples

Traffic split

You can use MeshTCPRoute to split TCP traffic between services with different tags and implement A/B testing or canary deployments.

Here’s an example of a MeshTCPRoute that splits the traffic from frontend_kuma-demo_svc_8080 to backend_kuma-demo_svc_3001 between versions:

apiVersion: kuma.io/v1alpha1
kind: MeshTCPRoute
metadata:
  name: tcp-route-1
  namespace: kuma-system
  labels:
    kuma.io/mesh: default
spec:
  targetRef:
    kind: MeshSubset
    tags:
      app: frontend
  to:
  - targetRef:
      kind: MeshService
      name: backend_kuma-demo_svc_3001
    rules:
    - default:
        backendRefs:
        - kind: MeshServiceSubset
          name: backend_kuma-demo_svc_3001
          tags:
            version: v0
          weight: 90
        - kind: MeshServiceSubset
          name: backend_kuma-demo_svc_3001
          tags:
            version: v1
          weight: 10

type: MeshTCPRoute
name: tcp-route-1
mesh: default
spec:
  targetRef:
    kind: MeshSubset
    tags:
      app: frontend
  to:
  - targetRef:
      kind: MeshService
      name: backend
    rules:
    - default:
        backendRefs:
        - kind: MeshServiceSubset
          name: backend_kuma-demo_svc_3001
          tags:
            version: v0
          weight: 90
        - kind: MeshServiceSubset
          name: backend_kuma-demo_svc_3001
          tags:
            version: v1
          weight: 10

Traffic redirection

You can use MeshTCPRoute to redirect outgoing traffic from one service to another.

Here’s an example of a MeshTCPRoute that redirects outgoing traffic originating at frontend_kuma-demo_svc_8080 from backend_kuma-demo_svc_3001 to external-backend:

apiVersion: kuma.io/v1alpha1
kind: MeshTCPRoute
metadata:
  name: tcp-route-1
  namespace: kuma-system
  labels:
    kuma.io/mesh: default
spec:
  targetRef:
    kind: MeshSubset
    tags:
      app: frontend
  to:
  - targetRef:
      kind: MeshService
      name: backend_kuma-demo_svc_3001
    rules:
    - default:
        backendRefs:
        - kind: MeshService
          name: external-backend_kuma-demo_svc

type: MeshTCPRoute
name: tcp-route-1
mesh: default
spec:
  targetRef:
    kind: MeshSubset
    tags:
      app: frontend
  to:
  - targetRef:
      kind: MeshService
      name: backend
    rules:
    - default:
        backendRefs:
        - kind: MeshService
          name: external-backend

Route policies with different types targeting the same destination

If multiple route policies with different types (MeshTCPRoute and MeshHTTPRoute for example) target the same destination, only a single route type with the highest specificity will be applied.

In this example, both MeshTCPRoute and MeshHTTPRoute target the same destination:

MeshTCPRoute:

# [...]
targetRef:
  kind: MeshSubset
  tags:
    app: frontend
to:
  - targetRef:
      kind: MeshService
      name: backend
      namespace: kuma-demo
      _port: 3001
      sectionName: http
    rules:
      - default:
          backendRefs:
            - kind: MeshService
              name: other-tcp-backend

MeshHTTPRoute:

# [...]
targetRef:
  kind: MeshSubset
  tags:
    app: frontend
to:
  - targetRef:
      kind: MeshService
      name: backend
      namespace: kuma-demo
      _port: 3001
      sectionName: http
    rules:
      - matches:
          - path:
              type: PathPrefix
              value: "/"
        default:
          backendRefs:
            - kind: MeshService
              name: other-http-backend

Depending on the backend’s protocol:

• MeshHTTPRoute will be applied if http, http2, or grpc are specified
• MeshTCPRoute will be applied if tcp or kafka is specified, or when nothing is specified

All policy configuration settings