Note: Canonical Services are supported automatically in Anthos Service Mesh version 1.6.8 and higher.
This page explains what a Canonical Service is in Anthos Service Mesh.
What is a Canonical Service?
Anthos Service Mesh 1.6.8 introduces support for Canonical Services, a conceptual and architectural model for representing your production workloads as a singular service that is easier to observe and manage. These workloads can span multiple clusters, disparate backend platforms, and different schemas and configurations.
For Compute Engine users: Canonical Service is roughly analogous to Managed Instance Groups, though a Canonical Service may be multi-region.
For Kubernetes users: Canonical Service is roughly analogous to the Kubernetes "app" concept and the Application CRD.
For Serverless users: Canonical Service is very similar to App Engine service and Cloud Run service concepts. The one difference is that Google Serverless services are inherently regional whereas Canonical Services are a global / multi-region abstraction.
For example, the following scenarios all describe ways that you might refer to a Canonical Service:
- A service has an outage.
- A service runs both on-premise and on a public cloud.
- Deploying a new revision of a service.
- The service Foo is sending too much traffic and may exceed our capacity.
Canonical Services exist within a single Mesh, which in Anthos Service Mesh means that they are also unique within an Environ and a Google Cloud Project (all of which are one-to-one with Mesh).
A given workload is only allowed to be part of one Canonical Service.
You can determine the full scope of a Canonical Service from the group of workloads that define it including:
- Hostnames and IP addresses
- Network and security policies
- Routing and load balancing
- VM and container images
- Physical or virtual infrastructure
- Geographic region(s)
- CI/CD system
- Source code
- Service level objectives and alerts
You can view dashboards that display these operational details for each service on the Anthos Services page.
Canonical Service requirements and limitations
Canonical Services are only available on Anthos Service Mesh version 1.6.8 and higher.
Each Canonical Service exists inside of a single Kubernetes/Istio namespace and cannot cross namespace boundaries.
You must give a Canonical Service a unique name within its parent namespace. For more information, see defining a Canonical Service.
Canonical Services can exist across multiple clusters and regions. While it is possible to break down resources and telemetry by cluster and region, those are not factors in determining the scope or uniqueness of a service.
Therefore, the unique identity of a Canonical Service is determined by:
mesh id + namespace + canonical name.
Revisions refer to incremental changes to a service which you can use to distinguish and identify different "versions" or "releases" of your services.
Differentiate between revisions of a Canonical Service by labeling an individual workload with its "canonical revision." This label is an arbitrary string that you can define. While the label may be set automatically in some cases, you or the CI/CD system that deploys the service must apply the label. For guidance on setting this label, see Defining a Canonical Service.
Note that multiple revisions can be in production at the same time. Running multiple revisions at once is most often used to accomplish:
- The progressive roll-out of a new binary, a new configuration, or both across all of the instances of one's service. In this case, both the old and new revisions are live during the transition.
- An "A/B test" or "live experiment," in which two different versions of the service are exposed to subsets of downstream callers to test the effect of a change.