rancher-charts/packages/rancher-monitoring/templates/crd-template

rancher-monitoring-crd

A Rancher chart that installs the CRDs used by rancher-monitoring.

How does this chart work?

This chart marshalls all of the CRD files placed in the crd-manifest directory into a ConfigMap that is installed onto a cluster alongside relevant RBAC (ServiceAccount, ClusterRoleBinding, ClusterRole, and PodSecurityPolicy).

Once the relevant dependent resourcees are installed / upgraded / rolled back, this chart executes a post-install / post-upgrade / post-rollback Job that:

• Patches any existing versions of the CRDs contained within the crd-manifest on the cluster to set spec.preserveUnknownFields=false; this step is required since, based on Kubernetes docs and a known workaround, such CRDs cannot be upgraded normally from apiextensions.k8s.io/v1beta1 to apiextensions.k8s.io/v1.
• Runs a kubectl apply on the CRDs that are contained within the crd-manifest ConfigMap to upgrade CRDs in the cluster

On an uninstall, this chart executes a separate post-delete Job that:

• Patches any existing versions of the CRDs contained within crd-manifest on the cluster to set metadata.finalizers=[]
• Runs a kubectl delete on the CRDs that are contained within the crd-manifest ConfigMap to clean up the CRDs from the cluster

Note: If the relevant CRDs already existed in the cluster at the time of install, this chart will absorb ownership of the lifecycle of those CRDs; therefore, on a helm uninstall, those CRDs will also be removed from the cluster alongside this chart.

Why can't we just place the CRDs in the templates/ directory of the main chart?

In Helm today, you cannot declare a CRD and declare a resource of that CRD's kind in templates/ without encountering a failure on render.

[Helm 3] Why can't we just place the CRDs in the crds/ directory of the main chart?

The Helm 3 crds/ directory only supports the installation of CRDs, but does not support the upgrade and removal of CRDs, unlike what this chart facilitiates.