Defining a Canonical Service

Note: Canonical Services are supported automatically in Cloud Service Mesh version 1.6.8 and higher.

Canonical Services is a group of workloads that implement the same service(s) and API(s). For supported workload types, Cloud Service Mesh automatically creates Canonical Service resources based on existing information from the Kubernetes API Server. This page explains what labels automatically define Canonical Services and how you can manually adjust the boundaries of your services. The currently supported workload instance types are:

  • Kubernetes Pods (including via Kubernetes Deployments, Kube Run Services, etc.)
  • Virtual Machine instances
  • Mesh-external services (specifically, ServiceEntry resources with a location of MESH_EXTERNAL)

What defines Canonical Services

Cloud Service Mesh determines the Canonical Service membership by reading the service.istio.io/canonical-name label on the Kubernetes configuration resource associated with each workload instance:

  • For Pods, the label is in the Kubernetes Pod resource
  • For VMs, the label in the Istio WorkloadEntry resource
  • For external services, the label is in the Istio ServiceEntry resource

Canonical Services have the same Kubernetes namespace as their associated workload instances and cannot span namespaces.

Automatic labeling rules

Cloud Service Mesh automatically groups your Pod- and VM-based workloads into Canonical Services with no action on your part. You only need to take action to:

  • Adjust labels for user/reader clarity
  • Override the default behavior.

Automatic labeling in Kubernetes Pods

Canonical Services focus around the Kubernetes app.kubernetes.io/name and app labels. Note that the former label takes precedence. If you use either of these two labels on your workloads, no further work is required.

Automatic labeling in Virtual Machines

To build Canonical Services on your VMs, you must add your VMs to a service mesh by configuring a WorkloadEntry resource in your Kubernetes API server.

Manually labeling

To manually apply or override a Canonical Service label apply the service.istio.io/canonical-name label to supported workload resource configurations. In order for an external service to be recognized as a Canonical Service, you must manually label the applicable ServiceEntry.

Manual labeling in Kubernetes Pods

To deploy many Pods at once using a Deployment, set the service.istio.io/canonical-name label on the PodTemplateSpec:

apiVersion: apps/v1 kind: Deployment metadata:  name: my-deployment  namespace: my-namespace spec:  replicas: 3  template:  metadata:  labels:  service.istio.io/canonical-name: my-service  spec:  containers:  ...

To label the Canonical Service of a single Pod, add the service.istio.io/canonical-name label to the labels section of your Pod configuration:

apiVersion: v1 kind: Pod metadata:  name: my-test-pod  namespace: my-namespace  labels:  service.istio.io/canonical-name: my-service spec:  ...

Label virtual machines manually

To label the Canonical Service of a single VM/WorkloadEntry, add the service.istio.io/canonical-name label to the "labels" section of your WorkloadEntry configuration:

apiVersion: networking.istio.io/v1alpha3 kind: WorkloadEntry metadata:  name: my-vm-123  namespace: my-namespace  labels:  service.istio.io/canonical-name: my-service spec:  ...

Label external services manually

To label the Canonical Service of a single external service/ServiceEntry, add the service.istio.io/canonical-name label to the "labels" section of your ServiceEntry configuration:

apiVersion: networking.istio.io/v1alpha3 kind: ServiceEntry metadata:  name: example-com  namespace: my-namespace  labels:  service.istio.io/canonical-name: an-external-service spec:  location: MESH_EXTERNAL  ...

What's next