flannel/vendor/k8s.io/kubernetes/docs/devel/generating-clientset.md

Generation and release cycle of clientset

Client-gen is an automatic tool that generates clientset based on API types. This doc introduces the use the client-gen, and the release cycle of the generated clientsets.

Using client-gen

The workflow includes four steps:

• Marking API types with tags: in pkg/apis/${GROUP}/${VERSION}/types.go, mark the types (e.g., Pods) that you want to generate clients for with the // +genclient=true tag. If the resource associated with the type is not namespace scoped (e.g., PersistentVolume), you need to append the nonNamespaced=true tag as well.

• Running the client-gen tool: you need to use the command line argument --input to specify the groups and versions of the APIs you want to generate clients for, client-gen will then look into pkg/apis/${GROUP}/${VERSION}/types.go and generate clients for the types you have marked with the genclient tags. For example, running:

  $ client-gen --input="api/v1,extensions/v1beta1" --clientset-name="my_release"
  

will generate a clientset named "my_release" which includes clients for api/v1 objects and extensions/v1beta1 objects. You can run $ client-gen --help to see other command line arguments.

• Adding expansion methods: client-gen only generates the common methods, such as Create() and Delete(). You can manually add additional methods through the expansion interface. For example, this file adds additional methods to Pod's client. As a convention, we put the expansion interface and its methods in file ${TYPE}_expansion.go. In most cases, you don't want to remove existing expansion files. So to make life easier, instead of creating a new clientset from scratch, you can copy and rename an existing clientset (so that all the expansion files are copied), and then run client-gen.

• Generating fake clients for testing purposes: client-gen will generate a fake clientset if the command line argument --fake-clientset is set. The fake clientset provides the default implementation, you only need to fake out the methods you care about when writing test cases.

The output of client-gen includes:

• clientset: the clientset will be generated at pkg/client/clientset_generated/ by default, and you can change the path via the --clientset-path command line argument.

• Individual typed clients and client for group: They will be generated at pkg/client/clientset_generated/${clientset_name}/typed/generated/${GROUP}/${VERSION}/

Released clientsets

At the 1.2 release, we have two released clientsets in the repo: internalclientset and release_1_2.

• internalclientset: because most components in our repo still deal with the internal objects, the internalclientset talks in internal objects to ease the adoption of clientset. We will keep updating it as our API evolves. Eventually it will be replaced by a versioned clientset.

• release_1_2: release_1_2 clientset is a versioned clientset, it includes clients for the core v1 objects, extensions/v1beta1, autoscaling/v1, and batch/v1 objects. We will NOT update it after we cut the 1.2 release. After the 1.2 release, we will create release_1_3 clientset and keep it updated until we cut release 1.3.

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