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Adding an API Group
===============

This document includes the steps to add an API group. You may also want to take a look at PR [#16621](https://github.com/kubernetes/kubernetes/pull/16621) and PR [#13146](https://github.com/kubernetes/kubernetes/pull/13146), which add API groups.

Please also read about [API conventions](api-conventions.md) and [API changes](api_changes.md) before adding an API group.

### Your core group package:

We plan on improving the way the types are factored in the future; see [#16062](https://github.com/kubernetes/kubernetes/pull/16062) for the directions in which this might evolve.

1. Create a folder in pkg/apis to hold you group. Create types.go in pkg/apis/`<group>`/ and pkg/apis/`<group>`/`<version>`/ to define API objects in your group;

2. Create pkg/apis/`<group>`/{register.go, `<version>`/register.go} to register this group's API objects to the encoding/decoding scheme (e.g., [pkg/apis/extensions/register.go](../../pkg/apis/extensions/register.go) and [pkg/apis/extensions/v1beta1/register.go](../../pkg/apis/extensions/v1beta1/register.go);

3. Add a pkg/apis/`<group>`/install/install.go, which is responsible for adding the group to the `latest` package, so that other packages can access the group's meta through `latest.Group`. You probably only need to change the name of group and version in the [example](../../pkg/apis/extensions/install/install.go)). You need to import this `install` package in {pkg/master, pkg/client/unversioned}/import_known_versions.go, if you want to make your group accessible to other packages in the kube-apiserver binary, binaries that uses the client package.

Step 2 and 3 are mechanical, we plan on autogenerate these using the cmd/libs/go2idl/ tool.

### Scripts changes and auto-generated code:

1. Generate conversions and deep-copies:

    1. Add your "group/" or "group/version" into hack/after-build/{update-generated-conversions.sh, update-generated-deep-copies.sh, verify-generated-conversions.sh, verify-generated-deep-copies.sh};
    2. Run hack/update-generated-conversions.sh, hack/update-generated-deep-copies.sh.

2. Generate files for Ugorji codec:

    1. Touch types.generated.go in pkg/apis/`<group>`{/, `<version>`};
    2. Run hack/update-codecgen.sh.

### Client (optional):

We are overhauling pkg/client, so this section might be outdated; see [#15730](https://github.com/kubernetes/kubernetes/pull/15730) for how the client package might evolve. Currently, to add your group to the client package, you need to

1. Create pkg/client/unversioned/`<group>`.go, define a group client interface and implement the client. You can take pkg/client/unversioned/extensions.go as a reference.

2. Add the group client interface to the `Interface` in pkg/client/unversioned/client.go and add method to fetch the interface. Again, you can take how we add the Extensions group there as an example.

3. If you need to support the group in kubectl, you'll also need to modify pkg/kubectl/cmd/util/factory.go.

### Make the group/version selectable in unit tests (optional):

1. Add your group in pkg/api/testapi/testapi.go, then you can access the group in tests through testapi.`<group>`;

2. Add your "group/version" to `KUBE_API_VERSIONS` and `KUBE_TEST_API_VERSIONS` in hack/test-go.sh.






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