Cat Facts Operator

A Kubernetes operator for all you cool cats and kittens.

Description

This is a proof-of-concept, just for fun, operator. This operator integrates a custom UI into the OpenShift Console through a Dynamic Plugin.

Cat Facts Operator is a Go-based Operator built with the Operator SDK. I built this as a proof-of-concept to learn operator development and distribution through Operator Lifecycle Management (OLM). This operator includes an OpenShift Dynamic Console Plugin that serves a front-end to manage operator resources.

What Does It Do?

Cat Facts Operator provides a Custom Resource Definition (CRD) for CatFact. A CatFact is a Kubernetes resource that contains metadata along with a fact about cats. It uses https://catfact.ninja/fact to generate facts about cats.

Requirements

• OKD/OpenShift 4.11 or later

NOTE: Cat Facts Operator should work on older versions of OpenShift and on other Kubernetes distributions; however, the console dynamic plugin UI (the main feature of this operator) will not be installed. The controller and CatFact CRD will install and should work as expected.

Installing

Cat Facts Operator is distributed through an OLM catalog. Cat Facts Operator is not included in any default OperatorHub catalog so you'll need to create a CatalogSource to install it.

Use the Import YAML feature of the OpenShift console or oc command line interface to create the CatalogSource object below.

# Apply this object to your cluster to add the catalog to OperatorHub.
# After ~1 minute, search for "Cat Facts" in OperatorHub.
apiVersion: operators.coreos.com/v1alpha1
kind: CatalogSource
metadata:
  name: cat-facts-catalog
  namespace: openshift-marketplace
spec:
  sourceType: grpc
  image: quay.io/rymiller/cat-facts-catalog:latest
  displayName: Cat Facts Catalog
  publisher: Ryan Miller
  updateStrategy:
    registryPoll:
      interval: 10m

After ~1 minute, navigate to OperatorHub and search for "Cat Facts".

Follow the prompts to install operator page. Accept the default options for everything except for Console Plugin. For security, OpenShift defaults Console Plugin to Disabled on operators that come from non-official catalogs. Select Enable for Console plugin and install the operator.

Within ~1 minute after the installation completes, you will be prompted to refresh your OpenShift console in the top-right corner.

How to Use Cat Facts

1. Navigate to Cat Facts > Cat Fact Catalog on the left-side navigation pane of the OpenShift console
2. Select Create CatFact
3. Select the new CatFact card to view it
4. Select Create CatFact again
5. Select Create CatFact 20 more times!!
6. If you get bored and want to delete all your CatFacts, select Delete All CatFacts
7. 🎉

Uninstalling

To uninstall, go to Operators > Installed Operators in the OpenShfit console. Select the Cat Facts Operator and uninstall.

After uninstalling, run these commands to clean up resources the operator leaves behind:

# Remove all CatFacts
oc delete -n cat-facts-operator $(oc get -n cat-facts-operator catfacts -o name)

# Remove the CatFacts CRD
oc delete crd catfacts.taco.moe

# Remove the OpenShift console plugin
oc delete consoleplugin cat-facts-operator-console-plugin

# Remove the cat-facts-operator namespace
oc delete namespace cat-facts-operator

# Optional: Remove the Cat Facts OLM CatalogSource
oc delete -n openshift-marketplace catalogsource cat-facts-catalog

Development

This project follows the Kubernetes [Operator Pattern].

It uses a [Controller] which provides a reconcile function responsible for synchronizing resources untile the desired state is reached on the cluster.

Additionally, this project includes a React JS-based OpenShift Console Dynamic Plugin, under the ./console directory. For details on developing the console plugin, view ./console/README.md.

The remainder of this document is specifically for developing and validating the Go-based operator.

Acknowledgments

Cat facts are generated by the public Cat Facts API.

Cat icons/emojis used in this project were created by Emily Jäger, licensed under CC BY-SA 4.0, and are available here.