1# client-go
2
3Go clients for talking to a [kubernetes](http://kubernetes.io/) cluster.
4
5We recommend using the `v0.x.y` tags for Kubernetes releases >= `v1.17.0` and
6`kubernetes-1.x.y` tags for Kubernetes releases < `v1.17.0`.
7
8The fastest way to add this library to a project is to run `go get k8s.io/client-go@latest` with go1.16+.
9See [INSTALL.md](/INSTALL.md) for detailed installation instructions and troubleshooting.
10
11[![GoDocWidget]][GoDocReference]
12
13[GoDocWidget]: https://godoc.org/k8s.io/client-go?status.svg
14[GoDocReference]:https://godoc.org/k8s.io/client-go
15
16## Table of Contents
17
18- [What's included](#whats-included)
19- [Versioning](#versioning)
20 - [Compatibility: your code <-> client-go](#compatibility-your-code---client-go)
21 - [Compatibility: client-go <-> Kubernetes clusters](#compatibility-client-go---kubernetes-clusters)
22 - [Compatibility matrix](#compatibility-matrix)
23 - [Why do the 1.4 and 1.5 branch contain top-level folder named after the version?](#why-do-the-14-and-15-branch-contain-top-level-folder-named-after-the-version)
24- [Kubernetes tags](#kubernetes-tags)
25- [How to get it](#how-to-get-it)
26- [How to use it](#how-to-use-it)
27- [Dependency management](#dependency-management)
28- [Contributing code](#contributing-code)
29
30### What's included
31
32* The `kubernetes` package contains the clientset to access Kubernetes API.
33* The `discovery` package is used to discover APIs supported by a Kubernetes API server.
34* The `dynamic` package contains a dynamic client that can perform generic operations on arbitrary Kubernetes API objects.
35* The `plugin/pkg/client/auth` packages contain optional authentication plugins for obtaining credentials from external sources.
36* The `transport` package is used to set up auth and start a connection.
37* The `tools/cache` package is useful for writing controllers.
38
39### Versioning
40
41- For each `v1.x.y` Kubernetes release, the major version (first digit)
42would remain `0`.
43
44- Bugfixes will result in the patch version (third digit) changing. PRs that are
45cherry-picked into an older Kubernetes release branch will result in an update
46to the corresponding branch in `client-go`, with a corresponding new tag
47changing the patch version.
48
49#### Branches and tags.
50
51We will create a new branch and tag for each increment in the minor version
52number. We will create only a new tag for each increment in the patch
53version number. See [semver](http://semver.org/) for definitions of major,
54minor, and patch.
55
56The HEAD of the master branch in client-go will track the HEAD of the master
57branch in the main Kubernetes repo.
58
59#### Compatibility: your code <-> client-go
60
61The `v0.x.y` tags indicate that go APIs may change in incompatible ways in
62different versions.
63
64See [INSTALL.md](INSTALL.md) for guidelines on requiring a specific
65version of client-go.
66
67#### Compatibility: client-go <-> Kubernetes clusters
68
69Since Kubernetes is backwards compatible with clients, older `client-go`
70versions will work with many different Kubernetes cluster versions.
71
72We will backport bugfixes--but not new features--into older versions of
73`client-go`.
74
75
76#### Compatibility matrix
77
78| | Kubernetes 1.23 | Kubernetes 1.24 | Kubernetes 1.25 | Kubernetes 1.26 | Kubernetes 1.27 | Kubernetes 1.28 |
79| ----------------------------- | --------------- | --------------- | --------------- | --------------- | --------------- | --------------- |
80| `kubernetes-1.23.0`/`v0.23.0` | ✓ | +- | +- | +- | +- | +- |
81| `kubernetes-1.24.0`/`v0.24.0` | +- | ✓ | +- | +- | +- | +- |
82| `kubernetes-1.25.0`/`v0.25.0` | +- | +- | ✓ | +- | +- | +- |
83| `kubernetes-1.26.0`/`v0.26.0` | +- | +- | +- | ✓ | +- | +- |
84| `kubernetes-1.27.0`/`v0.27.0` | +- | +- | +- | +- | ✓ | +- |
85| `kubernetes-1.28.0`/`v0.28.0` | +- | +- | +- | +- | +- | ✓ |
86| `HEAD` | +- | +- | +- | +- | +- | +- |
87
88Key:
89
90* `✓` Exactly the same features / API objects in both client-go and the Kubernetes
91 version.
92* `+` client-go has features or API objects that may not be present in the
93 Kubernetes cluster, either due to that client-go has additional new API, or
94 that the server has removed old API. However, everything they have in
95 common (i.e., most APIs) will work. Please note that alpha APIs may vanish or
96 change significantly in a single release.
97* `-` The Kubernetes cluster has features the client-go library can't use,
98 either due to the server has additional new API, or that client-go has
99 removed old API. However, everything they share in common (i.e., most APIs)
100 will work.
101
102See the [CHANGELOG](./CHANGELOG.md) for a detailed description of changes
103between client-go versions.
104
105| Branch | Canonical source code location | Maintenance status |
106| -------------- | ----------------------------------- | ------------------ |
107| `release-1.19` | Kubernetes main repo, 1.19 branch | =- |
108| `release-1.20` | Kubernetes main repo, 1.20 branch | =- |
109| `release-1.21` | Kubernetes main repo, 1.21 branch | =- |
110| `release-1.22` | Kubernetes main repo, 1.22 branch | =- |
111| `release-1.23` | Kubernetes main repo, 1.23 branch | =- |
112| `release-1.24` | Kubernetes main repo, 1.24 branch | =- |
113| `release-1.25` | Kubernetes main repo, 1.25 branch | ✓ |
114| `release-1.26` | Kubernetes main repo, 1.26 branch | ✓ |
115| `release-1.27` | Kubernetes main repo, 1.27 branch | ✓ |
116| `release-1.28` | Kubernetes main repo, 1.28 branch | ✓ |
117| client-go HEAD | Kubernetes main repo, master branch | ✓ |
118
119Key:
120
121* `✓` Changes in main Kubernetes repo are actively published to client-go by a bot
122* `=` Maintenance is manual, only severe security bugs will be patched.
123* `-` Deprecated; please upgrade.
124
125#### Deprecation policy
126
127We will maintain branches for at least six months after their first stable tag
128is cut. (E.g., the clock for the release-2.0 branch started ticking when we
129tagged v2.0.0, not when we made the first alpha.) This policy applies to
130every version greater than or equal to 2.0.
131
132#### Why do the 1.4 and 1.5 branch contain top-level folder named after the version?
133
134For the initial release of client-go, we thought it would be easiest to keep
135separate directories for each minor version. That soon proved to be a mistake.
136We are keeping the top-level folders in the 1.4 and 1.5 branches so that
137existing users won't be broken.
138
139### Kubernetes tags
140
141This repository is still a mirror of
142[k8s.io/kubernetes/staging/src/client-go](https://github.com/kubernetes/kubernetes/tree/master/staging/src/k8s.io/client-go),
143the code development is still done in the staging area.
144
145Since Kubernetes `v1.8.0`, when syncing the code from the staging area,
146we also sync the Kubernetes version tags to client-go, prefixed with
147`kubernetes-`. From Kubernetes `v1.17.0`, we also create matching semver
148`v0.x.y` tags for each `v1.x.y` Kubernetes release.
149
150For example, if you check out the `kubernetes-1.17.0` or the `v0.17.0` tag in
151client-go, the code you get is exactly the same as if you check out the `v1.17.0`
152tag in Kubernetes, and change directory to `staging/src/k8s.io/client-go`.
153
154The purpose is to let users quickly find matching commits among published repos,
155like [sample-apiserver](https://github.com/kubernetes/sample-apiserver),
156[apiextension-apiserver](https://github.com/kubernetes/apiextensions-apiserver),
157etc. The Kubernetes version tag does NOT claim any backwards compatibility
158guarantees for client-go. Please check the [semantic versions](#versioning) if
159you care about backwards compatibility.
160
161### How to get it
162
163To get the latest version, use go1.16+ and fetch using the `go get` command. For example:
164
165```
166go get k8s.io/client-go@latest
167```
168
169To get a specific version, use go1.11+ and fetch the desired version using the `go get` command. For example:
170
171```
172go get k8s.io/client-go@v0.20.4
173```
174
175See [INSTALL.md](/INSTALL.md) for detailed instructions and troubleshooting.
176
177### How to use it
178
179If your application runs in a Pod in the cluster, please refer to the
180in-cluster [example](examples/in-cluster-client-configuration), otherwise please
181refer to the out-of-cluster [example](examples/out-of-cluster-client-configuration).
182
183### Dependency management
184
185For details on how to correctly use a dependency management for installing client-go, please see [INSTALL.md](INSTALL.md).
186
187### Contributing code
188Please send pull requests against the client packages in the Kubernetes main [repository](https://github.com/kubernetes/kubernetes). Changes in the staging area will be published to this repository every day.
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