Virtual Outbound

    Possible use cases are:

    1) Preserving hostnames when migrating to service mesh. 2) Providing multiple hostnames for reaching the same service, for example when renaming or for usability. 3) Providing specific routes, for example to reach a specific pod in a service with StatefulSets on Kubernetes, or to add a URL to reach a specific version of a service. 4) Expose multiple inbounds on different ports.

    Limitations:

    • Complex virtual outbounds do not work for cross-zone traffic. This is because only service tags are propagated across zones.
    • When duplicate combinations are detected, the virtual outbound with the highest priority takes over. For more information, see the documentation on how Kuma chooses the right policy. All duplicate instances are logged.

    conf.selectors are used to specify which proxies this policy applies to.

    For example a proxy with this definition:

    and a virtual outbound with this definition:

    1. type: VirtualOutbound
    2. mesh: default
    3. name: test
    4. selectors:
    5.   - match:
    6.       kuma.io/service: "*"
    7. conf:
    8.   host: "{{.v}}.{{.service}}.mesh"
    9.   port: "{{.port}}"
    10.   parameters:
    11.     - name: service
    12.       tagKey: "kuma.io/service"
    13.     - name: port
    14.       tagKey: port
    15.     - name: v
    16.       tagKey: version

    Additional requirements:

    • .
    • Either data plane proxy DNS, or else the value of conf.host must end with the value of dns_server.domain (default value .mesh).
    • name must be alphanumeric. (Used as a go template key).
    • Each value of name must be unique.
    • kuma.io/service must be specified even if it’s unused in the template. (Prevents defining hostnames that spans services).

    The default value of tagKey is the value of name.

    For each virtual outbound, the Kuma control plane processes all data plane proxies that match the selector. It then applies the templates for conf.host and conf.port and assigns a virtual IP address for each hostname.

    1. apiVersion: kuma.io/v1alpha1
    2. kind: VirtualOutbound
    3. mesh: default
    4. metadata:
    6. spec:
    7.     selectors:
    8.       - match:
    9.     conf:
    10.       host: "{{.service}}.mesh"
    11.       port: "80"
    12.       parameters:
    13.         - name: service
    14.           tagKey: "kuma.io/service"
    1. apiVersion: kuma.io/v1alpha1
    2. kind: VirtualOutbound
    3. mesh: default
    4. metadata:
    5.   name: versioned
    6. spec:
    7.     selectors:
    8.       - match:
    9.           kuma.io/service: "*"
    10.     conf:
    11.       host: "{{.service}}.{{.version}}.mesh"
    12.       port: "80"
    13.       parameters:
    14.         - name: service
    15.           tagKey: "kuma.io/service"
    16.         - name: version
    17.           tagKey: "kuma.io/version"
    1. type: VirtualOutbound
    2. mesh: default
    3. name: versioned
    4. spec:
    5.     selectors:
    6.       - match:
    7.           kuma.io/service: "*"
    8.     conf:
    9.       host: "{{.service}}.{{.version}}.mesh"
    11.       parameters:
    12.         - name: service
    13.           tagKey: "kuma.io/service"
    14.           tagKey: "kuma.io/version"
    1. type: VirtualOutbound
    2. mesh: default
    3. name: host-port
    4. selectors:
    5.   - match:
    6.       kuma.io/service: "*"
    7. conf:
    8.   host: "{{.hostname}}"
    9.   port: "{{.port}}"
    10.   parameters:
    11.     - name: hostname
    12.       tagKey: "my.mesh/hostname"
    13.     - name: port
    14.       tagKey: "my.mesh/port"
    15.     - name: service

    Enables reaching specific data plane proxies for a service. Useful for running distributed databases such as Kafka or Zookeeper.

    1. apiVersion: kuma.io/v1alpha1
    2. kind: VirtualOutbound
    3. mesh: default
    4. metadata:
    5.   name: instance
    6. spec:
    7.   selectors:
    8.     - match:
    9.         kuma.io/service: "*"
    10.         statefulset.kubernetes.io/pod-name: "*"
    11.   conf:
    12.     host: "{{.svc}}.{{.inst}}.mesh"
    13.     port: "8080"
    14.     parameters:
    15.       - name: "svc"
    16.         tagKey: "kuma.io/service"
    18.         tagKey: "statefulset.kubernetes.io/pod-name"