Introducing Kubernetes API Version v1beta3

Thursday, April 16, 2015

Introducing Kubernetes API Version v1beta3

We’ve been hard at work on cleaning up the API over the past several months (see https://github.com/GoogleCloudPlatform/kubernetes/issues/1519 for details). The result is v1beta3, which is considered to be the release candidate for the v1 API.

We would like you to move to this new API version as soon as possible. v1beta1 and v1beta2 are deprecated, and will be removed by the end of June, shortly after we introduce the v1 API.

As of the latest release, v0.15.0, v1beta3 is the primary, default API. We have changed the default kubectl and client API versions as well as the default storage version (which means objects persisted in etcd will be converted from v1beta1 to v1beta3 as they are rewritten). 

You can take a look at v1beta3 examples such as:

https://github.com/GoogleCloudPlatform/kubernetes/tree/master/examples/guestbook/v1beta3

https://github.com/GoogleCloudPlatform/kubernetes/tree/master/examples/walkthrough/v1beta3

https://github.com/GoogleCloudPlatform/kubernetes/tree/master/examples/update-demo/v1beta3

To aid the transition, we’ve also created a conversion tool and put together a list of important different API changes.

• The resource id is now called name.
• name, labels, annotations, and other metadata are now nested in a map called metadata
• desiredState is now called spec, and currentState is now called status
• /minions has been moved to /nodes, and the resource has kind Node
• The namespace is required (for all namespaced resources) and has moved from a URL parameter to the path:/api/v1beta3/namespaces/{namespace}/{resource_collection}/{resource_name}
• The names of all resource collections are now lower cased - instead of replicationControllers, usereplicationcontrollers.
• To watch for changes to a resource, open an HTTP or Websocket connection to the collection URL and provide the?watch=true URL parameter along with the desired resourceVersion parameter to watch from.
• The container entrypoint has been renamed to command, and command has been renamed to args.
• Container, volume, and node resources are expressed as nested maps (e.g., resources{cpu:1}) rather than as individual fields, and resource values support scaling suffixes rather than fixed scales (e.g., milli-cores).
• Restart policy is represented simply as a string (e.g., “Always”) rather than as a nested map (“always{}”).
• The volume source is inlined into volume rather than nested.
• Host volumes have been changed to hostDir to hostPath  to better reflect that they can be files or directories

And the most recently generated Swagger specification of the API is here:

http://kubernetes.io/third_party/swagger-ui/#!/v1beta3

More details about our approach to API versioning and the transition can be found here:

https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/api.md

Another change we discovered is that with the change to the default API version in kubectl, commands that use “-o template” will break unless you specify “–api-version=v1beta1” or update to v1beta3 syntax. An example of such a change can be seen here:

https://github.com/GoogleCloudPlatform/kubernetes/pull/6377/files

If you use “-o template”, I recommend always explicitly specifying the API version rather than relying upon the default. We may add this setting to kubeconfig in the future.

Let us know if you have any questions. As always, we’re available on IRC (#google-containers) and github issues.