Pods and Services

To be a part of an Istio service mesh, pods and services in a Kubernetes cluster must satisfy the following requirements:

• Named service ports: Service ports must be named. The port name key/value pairs must have the following syntax: name: <protocol>[-<suffix>]. To take advantage of Istio’s routing features, replace <protocol> with one of the following values:

  • grpc
  • http
  • http2
  • https
  • mongo
  • mysql
  • redis
  • tcp
  • tls
  • udp

  For example, name: http2-foo or name: http are valid port names, but name: http2foo is not. If the port name does not begin with a recognized prefix or if the port is unnamed, traffic on the port is treated as plain TCP traffic unless the port explicitly uses Protocol: UDP to signify a UDP port.

• Pod ports: Pods must include an explicit list of the ports each container listens on. Use a containerPort configuration in the container specification for each port. Any unlisted ports bypass the Istio proxy.

• Service association: A pod must belong to at least one Kubernetes service even if the pod does NOT expose any port. If a pod belongs to multiple Kubernetes services, the services cannot use the same port number for different protocols, for instance HTTP and TCP.

• Deployments with app and version labels: We recommend adding an explicit app label and version label to deployments. Add the labels to the deployment specification of pods deployed using the Kubernetes Deployment. The app and version labels add contextual information to the metrics and telemetry Istio collects.

  • The app label: Each deployment specification should have a distinct app label with a meaningful value. The app label is used to add contextual information in distributed tracing.

  • The version label: This label indicates the version of the application corresponding to the particular deployment.

• Application UIDs: Ensure your pods do not run applications as a user with the user ID (UID) value of 1337.

• NET_ADMIN capability: If your cluster enforces pod security policies, pods must allow the NET_ADMIN capability. If you use the Istio CNI Plugin, this requirement no longer applies. To learn more about the NET_ADMIN capability, visit Required Pod Capabilities.

Ports used by Istio

The following ports and protocols are used by Istio. Ensure that there are no TCP headless services using a TCP port used by one of Istio’s services.