plain

README

Plain Provisioner

Summary

The plain provisioner is a core rukpak provisioner that knows how to interact with bundles of a particular format. These plain+v0 bundles, or plain bundles, are simply container images containing a set of static Kubernetes YAML manifests in a given directory. For example, below is an example Dockerfile that builds a plain plain+v0 bundle from a directory containing static manifests.

FROM scratch
COPY /manifests /manifests

where the given manifests directory contains the Kubernetes resources required to deploy an application, for example:

manifests
├── namespace.yaml
├── cluster_role.yaml
├── role.yaml
├── serviceaccount.yaml
├── cluster_role_binding.yaml
├── role_binding.yaml
└── deployment.yaml

Note: The static manifests must be located in the root-level /manifests directory for the bundle image to be a valid plain+v0 bundle that the provisioner can unpack.

The plain provisioner is able to unpack a given plain+v0 bundle onto a cluster and then instantiate it, making the content of the bundle available in the cluster. It does so by reconciling Bundle and BundleInstance types that have the spec.provisionerClassName field set to core.rukpak.io/plain. This field must be set to the correct provisioner name in order for the plain provisioner to see and interact with the bundle.

Below is an example of the provisioner reconciliation flow:

graph TD
    C[Provisioner]
    C -->|Watches| D[Bundle]
    C -->|Watches| E[BundleInstance]
    D -->|References| F[Content]
    E -->|Creates/Manages| F[Content]

Use cases

Install and apply a specific version of a bundle

The plain provisioner can install and make available a specific plain+v0 bundle in the cluster.

Simply create a Bundle resource pointing to a specific version of your bundle, and a BundleInstance which references that bundle. The plain provisioner will unpack the provided Bundle onto the cluster, and eventually make the content available on the cluster.

apiVersion: core.rukpak.io/v1alpha1
kind: Bundle
metadata:
  name: my-bundle
spec:
  image: my-bundle@sha256:xyz123
  provisionerClassName: core.rukpak.io/plain
---
apiVersion: core.rukpak.io/v1alpha1
kind: BundleInstance
metadata:
  name: my-bundle-instance
spec:
  provisionerClassName: core.rukpak.io/plain
  bundleName: my-bundle

First, the Bundle will be in the Pending stage as the provisioner sees it and begins unpacking the referenced content:

NAME          IMAGE                                        PHASE     AGE
my-bundle     my-bundle@sha256:xyz123                      Pending   3s

Then eventually, as the bundle content is unpacked onto the cluster via the defined storage mechanism, the bundle status will be updated to Unpacked, indicating that all its contents have been stored on-cluster.

NAME          IMAGE                                        PHASE      AGE
my-bundle     my-bundle@sha256:xyz123                      Unpacked   10s

Now that the bundle has been unpacked, the provisioner is able to create the resources in the bundle on the cluster. These resources will be owned by the corresponding BundleInstance. Creating the BundleInstance on-cluster results in an InstallationSucceeded Phase if the application of resources to the cluster was successful.

NAME                 DESIRED BUNDLE   INSTALLED BUNDLE   INSTALL STATE           AGE
my-bundle-instance   my-bundle        my-bundle          InstallationSucceeded   11s

Note: Creation of more than one BundleInstance from the same Bundle will likely result in an error.

Make bundle content available but do not install it

There is a natural separation between sourcing of the content and application of that content via two separate RukPak APIs, Bundle and BundleInstance. A user can specify a particular Bundle to be available in the cluster for inspection before any application of the resources. Given a Bundle resource named my-bundle, the plain provisioner will pull down and unpack the bundle to a set of ConfigMaps.

By default, rukpak-system is the configured namespace for deploying plain provisioner-related system resources.

Surfacing the content of a bundle in a more user-friendly way, via a plugin or additional API, is on the RukPak roadmap.

Pivoting between bundle versions

The BundleInstance API is meant to indicate the version of the bundle that should be active within the cluster. Given two unpacked bundles in the cluster, my-bundle-v0.0.1 and my-bundle-v0.0.2, the spec.bundleName field of the related BundleInstance can be updated to pivot to a different version. For example by pivoting from an older version, to the newer version, by updating the spec.bundleName field the plain provisioner will create the new bundle content on-cluster and remove the old content. The provisioner also continually reconciles the created content via dynamic watches to ensure that all resources referenced by the bundle are present on the cluster.

Running locally

Setup

To experiment with the plain provisioner locally, first setup a local cluster, or simply have kind installed locally.

Once the cluster has been setup, take the following steps:

• Clone the repository via git clone https://github.com/operator-framework/rukpak
• Navigate to the repository via cd rukpak
• Run make run to build and deploy the provisioner onto the local cluster.

Installing the Combo Operator

From there, create some Bundles and BundleInstance types to see the provisioner in action. For an example bundle to use, the combo operator is a good candidate.

Create the bundle:

$ kubectl apply -f -<<EOF
apiVersion: core.rukpak.io/v1alpha1
kind: Bundle
metadata:
  name: combo-v0.0.1
spec:
  image: quay.io/tflannag/bundle:combo-operator-v0.0.1
  provisionerClassName: core.rukpak.io/plain
EOF
bundle.core.rukpak.io/combo-v0.0.1 created

Check the Bundle status via kubectl get bundle combo-0.0.1. Eventually the Bundle should show up as Unpacked.

$ kubectl get bundle combo-v0.0.1
NAME           IMAGE                                           PHASE      AGE
combo-v0.0.1   quay.io/tflannag/bundle:combo-operator-v0.0.1   Unpacked   10s

Create the combo BundleInstance referencing the combo Bundle available in the cluster.

Note: it's perfectly valid to create a Bundle and BundleInstance referencing that Bundle at the same time. There is no specific ordering required, which is perfect for GitOps flows, and eventually both the Bundle and BundleInstance would succeed.

$ kubectl apply -f -<<EOF
apiVersion: core.rukpak.io/v1alpha1
kind: BundleInstance
metadata:
  name: combo
spec:
  provisionerClassName: core.rukpak.io/plain
  bundleName: combo-v0.0.1
EOF
bundleinstance.core.rukpak.io/combo created

Check the BundleInstance status to ensure that the installation was successful.

$ kubectl get bundleinstance combo
NAME    DESIRED BUNDLE   INSTALLED BUNDLE   INSTALL STATE           AGE
combo   combo-v0.0.1     combo-v0.0.1       InstallationSucceeded   10s

From there, check out the combo operator deployment and ensure that the operator is present on the cluster.

$ kubectl -n combo get deployments.apps combo-operator
NAME             READY   UP-TO-DATE   AVAILABLE   AGE
combo-operator   1/1     1            1           10s

$ kubectl -n combo get deployments.apps combo-operator -o yaml | grep 'image:' | xargs
image: quay.io/tflannag/combo:v0.0.1

The operator should be successfully installed.

Next, the plain provisioner continually reconciles BundleInstance resources. Let's try deleting the combo deployment:

$ kubectl -n combo delete deployments.apps combo-operator
deployment.apps "combo-operator" deleted

Check for the deployment again, it will be back on the cluster. The provisioner ensures that all resources required for the BundleInstance to run are accounted for on-cluster.

Upgrading the Combo Operator

Let's say the combo operator released a new patch version, and we want to upgrade to that version.

Note: Currently upgrading a BundleInstance is a manual process that involves updating the spec.BundleName being referenced, and point to a new Bundle's metadata.Name. Automatically pivoting to a new Bundle is on the roadmap.

First, create a new Bundle resource that points to this new plain+v0 bundle container image:

$ kubectl apply -f -<<EOF
apiVersion: core.rukpak.io/v1alpha1
kind: Bundle
metadata:
  name: combo-v0.0.2
spec:
  image: quay.io/tflannag/bundle:combo-operator-v0.0.2
  provisionerClassName: core.rukpak.io/plain
EOF

And wait until that Bundle is reporting an Unpacked status:

$ kubectl get bundles combo-v0.0.2
NAME           IMAGE                                           PHASE      AGE
combo-v0.0.2   quay.io/tflannag/bundle:combo-operator-v0.0.2   Unpacked   10s

Once the Bundle has been unpacked, update the existing combo BundleInstance resource to point to the new combo-v0.0.2 Bundle:

$ kubectl patch bundleinstance combo --type='merge' -p '{"spec":{"bundleName": "combo-v0.0.2"}}'
bundleinstance.core.rukpak.io/combo patched

And verify that the BundleInstance combo resource now points to the new Bundle version:

$ kubectl get bundleinstance combo
NAME    DESIRED BUNDLE   INSTALLED BUNDLE   INSTALL STATE           AGE
combo   combo-v0.0.2     combo-v0.0.2       InstallationSucceeded   10s

And check that the combo-operator deployment in the combo namespace is healthy and contains a new container image:

$ kubectl -n combo get deployment
NAME             READY   UP-TO-DATE   AVAILABLE   AGE
combo-operator   1/1     1            1           10s

$ kubectl -n combo get deployments.apps combo-operator -o yaml | grep 'image:' | xargs
image: quay.io/tflannag/combo:v0.0.2

Notice that the container image has changed since we had first installed the combo operator.

Deleting the Combo Operator

To cleanup from the installation, simply remove the BundleInstance from the cluster. This will remove all references resources including the deployment, RBAC, and the operator namespace. Then the Bundle can be removed as well, which removes any unpacked manifests from the cluster.

$ kubectl delete bundleinstances.core.rukpak.io combo
bundleinstance.core.rukpak.io "combo" deleted

$ kubectl delete bundle combo-v0.0.1
bundle.core.rukpak.io "combo-v0.0.1" deleted

$ kubectl delete bundle combo-v0.0.2
bundle.core.rukpak.io "combo-v0.0.2" deleted

The cluster state is now the same as it was prior to installing the operator.