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CRD versioning Public Documentation (#8834)
* CRD versioning Public Documentation * Copyedit Signed-off-by: Misty Stanley-Jones <mistyhacks@google.com> * Address feedback * More rewrites * Address feedback * Update main CRD page in light of versioning * Reorg CRD docs * Further reorg * Tweak title
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content/en/docs/tasks/access-kubernetes-api/custom-resources/_index.md
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| --- | ||
| title: "Use Custom Resources" | ||
| weight: 10 | ||
| --- | ||
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...access-kubernetes-api/custom-resources/custom-resource-definition-versioning.md
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| --- | ||
| title: Versions of CustomResourceDefinitions | ||
| reviewers: | ||
| - mbohlool | ||
| - sttts | ||
| - liggitt | ||
| content_template: templates/task | ||
| weight: 30 | ||
| --- | ||
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| {{% capture overview %}} | ||
| This page explains how to add versioning information to | ||
| [CustomResourceDefinitions](/docs/reference/generated/kubernetes-api/{{< param "version" >}}/#customresourcedefinition-v1beta1-apiextensions), to indicate the stability | ||
| level of your CustomResourceDefinitions. It also describes how to upgrade an | ||
| object from one version to another. | ||
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| {{< note >}} | ||
| **Note**: All specified versions must use the same schema. The is no schema | ||
| conversion between versions. | ||
| {{< /note >}} | ||
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| {{% /capture %}} | ||
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| {{% capture prerequisites %}} | ||
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| {{< include "task-tutorial-prereqs.md" >}} {{< version-check >}} | ||
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| * Make sure your Kubernetes cluster has a master version of 1.11.0 or higher. | ||
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| * Read about [custom resources](/docs/concepts/api-extension/custom-resources/). | ||
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| {{% /capture %}} | ||
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| {{% capture steps %}} | ||
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| ## Overview | ||
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| The CustomResourceDefinition API supports a `versions` field that you can use to | ||
| support multiple versions of custom resources that you have developed, and | ||
| indicate the stability of a given custom resource. All versions must currently | ||
| use the same schema, so if you need to add a field, you must add it to all | ||
| versions. | ||
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| {{< note >}} | ||
| Earlier iterations included a `version` field instead of `versions`. The | ||
| `version` field is deprecated and optional, but if it is not empty, it must | ||
| match the first item in the `versions` field. | ||
| {{< /note >}} | ||
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| ## Specify multiple versions | ||
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| This example shows a CustomResourceDefinition with two versions. The comments in | ||
| the YAML provide more context. | ||
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| ```yaml | ||
| apiVersion: apiextensions.k8s.io/v1beta1 | ||
| kind: CustomResourceDefinition | ||
| metadata: | ||
| # name must match the spec fields below, and be in the form: <plural>.<group> | ||
| name: crontabs.example.com | ||
| spec: | ||
| # group name to use for REST API: /apis/<group>/<version> | ||
| group: example.com | ||
| # list of versions supported by this CustomResourceDefinition | ||
| versions: | ||
| - name: v1beta1 | ||
| # Each version can be enabled/disabled by Served flag. | ||
| served: true | ||
| # One and only one version must be marked as the storage version. | ||
| storage: true | ||
| - name: v1 | ||
| served: true | ||
| storage: false | ||
| # either Namespaced or Cluster | ||
| scope: Namespaced | ||
| names: | ||
| # plural name to be used in the URL: /apis/<group>/<version>/<plural> | ||
| plural: crontabs | ||
| # singular name to be used as an alias on the CLI and for display | ||
| singular: crontab | ||
| # kind is normally the CamelCased singular type. Your resource manifests use this. | ||
| kind: CronTab | ||
| # shortNames allow shorter string to match your resource on the CLI | ||
| shortNames: | ||
| - ct | ||
| ``` | ||
| You can save the CustomResourceDefinition in a YAML file, then use | ||
| `kubectl create` to create it. | ||
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| ```shell | ||
| kubectl create -f my-versioned-crontab.yaml | ||
| ``` | ||
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| After creation, the API server starts to serve each enabled version at an HTTP | ||
| REST endpoint. In the above example, the API versions are available at | ||
| `/apis/example.com/v1beta1` and `/apis/example.com/v1`. | ||
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| ### Version priority | ||
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| Regardless of the order in which versions are defined in a | ||
| CustomResourceDefinition, the version with the highest priority is used by | ||
| kubectl as the default version to access objects. The priority is determined | ||
| by parsing the _name_ field to determine the version number, the stability | ||
| (GA, Beta, or Alpha), and the sequence within that stability level. | ||
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| The algorithm used for sorting the versions is designed to sort versions in the | ||
| same way that the Kubernetes project sorts Kubernetes versions. Versions start with a | ||
| `v` followed by a number, an optional `beta` or `alpha` designation, and | ||
| optional additional versioning information. Broadly, a version string might look | ||
| like `v2` or `v2beta1`. Versions are sorted using the following algorithm: | ||
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| - Entries that follow Kubernetes version patterns are sorted before those that | ||
| do not. | ||
| - For entries that follow Kubernetes version patterns, the numeric portions of | ||
| the version string is sorted largest to smallest. | ||
| - If the strings `beta` or `alpha` follow the first numeric portion, they sorted | ||
| in that order, after the equivalent string without the `beta` or `alpha` | ||
| suffix (which is presumed to be the GA version). | ||
| - If another number follows the `beta`, or `alpha`, those numbers are also | ||
| sorted from largest to smallest. | ||
| - Strings that don't fit the above format are sorted alphabetically and the | ||
| numeric portions are not treated specially. Notice that in the example below, | ||
| `foo1` is sorted above `foo10`. This is different from the sorting of the | ||
| numeric portion of entries that do follow the Kubernetes version patterns. | ||
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| This might make sense if you look at the following sorted version list: | ||
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| ```none | ||
| - v10 | ||
| - v2 | ||
| - v1 | ||
| - v11beta2 | ||
| - v10beta3 | ||
| - v3beta1 | ||
| - v12alpha1 | ||
| - v11alpha2 | ||
| - foo1 | ||
| - foo10 | ||
| ``` | ||
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| For the example in [Specify multiple versions](#specify-multiple-versions), the | ||
| version sort order is `v1`, followed by `v1beta1`. This causes the kubectl | ||
| command to use `v1` as the default version unless the provided object specifies | ||
| the version. | ||
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| ## Writing, reading, and updating versioned CustomResourceDefinition objects | ||
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| When an object is written, it is persisted at the version designated as the | ||
| storage version at the time of the write. If the storage version changes, | ||
| existing objects are never converted automatically. However, newly-created | ||
| or updated objects are created at the new storage version. It is possible for an | ||
| object to have been written at a version that is no longer served. | ||
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| When you read an object, you specify the version as part of the path. If you | ||
| specify a version that is different from the object's persisted version, | ||
| Kubernetes returns the object to you at the version you requested, but does not | ||
| modify the persisted object. You can request an object at any version that is | ||
| currently served. | ||
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| If you update an existing object, it is rewritten at the version that is | ||
| currently the storage version. This is the only way that objects can change from | ||
| one version to another. | ||
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| To illustrate this, consider the following hypothetical series of events: | ||
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| 1. The storage version is `v1beta`. You create an object. It is persisted in | ||
| storage at version `v1beta1` | ||
| 2. You add version `v1` to your CustomResourceDefinition and designate it as | ||
| the storage version. | ||
| 3. You read your object at version `v1beta`, then you read the object again at | ||
| version `v1`. Both returned objects are identical except for the apiVersion | ||
| field. | ||
| 4. You create a new object. It is persisted in storage at version `v1`. You now | ||
| have two objects, one of which is at `v1beta`, and the other of which is at | ||
| `v1`. | ||
| 5. You update the first object. It is now persisted at version `v1` since that | ||
| is the current storage version. | ||
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| ### Previous storage versions | ||
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| The API server records each version which has ever been marked as the storage | ||
| version in the status field `storedVersions`. Objects may have been persisted | ||
| at any version that has ever been designated as a storage version. No objects | ||
| can exist in storage at a version that has never been a storage version. | ||
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| ## Upgrade existing objects to a new stored version | ||
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| When deprecating versions and dropping support, devise a storage upgrade | ||
| procedure. The following is an example procedure to upgrade from `v1beta1` | ||
| to `v1`. | ||
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| 1. Set `v1` as the storage in the CustomResourceDefinition file and apply it | ||
| using kubectl. The `storedVersions` is now `v1beta1, v1`. | ||
| 2. Write an upgrade procedure to list all existing objects and write them with | ||
| the same content. This forces the backend to write objects in the current | ||
| storage version, which is `v1`. | ||
| 3. Update the CustomResourceDefinition `Status` by removing `v1beta1` from | ||
| `storedVersions` field. | ||
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| {{% /capture %}} |
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