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38 lines
1.5 KiB
38 lines
1.5 KiB
# Custom Resource Definitions
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This section of the Best Practices Guide deals with creating and using Custom Resource Definition
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objects.
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When working with Custom Resource Definitions (CRDs), it is important to distinguish
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two different pieces:
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- There is a declaration of a CRD. This is the YAML file that has the kind `CustomResourceDefinition`
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- Then there are resources that _use_ the CRD. Say a CRD defines `foo.example.com/v1`. Any resource
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that has `apiVersion: example.com/v1` and kind `Foo` is a resource that uses the CRD.
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## Install a CRD Declaration Before Using the Resource
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Helm is optimized to load as many resources into Kubernetes as fast as possible.
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By design, Kubernetes can take an entire set of manifests and bring them all
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online (this is called the reconciliation loop).
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But there's a difference with CRDs.
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For a CRD, the declaration must be registered before any resources of that CRDs
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kind(s) can be used. And the registration process sometimes takes a few seconds.
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### Method 1: Separate Charts
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One way to do this is to put the CRD definition in one chart, and then put any
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resources that use that CRD in _another_ chart.
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In this method, each chart must be installed separately.
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### Method 2: Pre-install Hooks
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To package the two together, add a `pre-install` hook to the CRD definition so
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that it is fully installed before the rest of the chart is executed.
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Note that if you create the CRD with a `pre-install` hook, that CRD definition
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will not be deleted when `helm delete` is run.
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