gitops-controller

A kubebuilder-based simple gitops controller that aims to keep your cluster state in sync with a github repository of plain k8s yaml (no support for kustomize/helm).

Description

This is a toy project to learn how to write a fairly complicated k8s controller that has to interact with a CRD and 3rd party APIs. It aims to implement a very simple version of ArgoCD, namely, that it will keep cluster state in sync with k8s manifests defined in a git repo.

More sopistication may be added over time the largest limitations are:

• Only works with github repositories
• Does not trigger sync on changes to tracked resources
• Will perform sync every 3 minutes by default unless the Application CRD is updated, in which case sync will be triggered automatically
• Does not check resource diffs, always syncs all resources.

Getting Started

You’ll need a Kubernetes cluster to run against. You can use KIND to get a local cluster for testing, or run against a remote cluster. Note: Your controller will automatically use the current context in your kubeconfig file (i.e. whatever cluster kubectl cluster-info shows).

Running on the cluster

1. Install Instances of Custom Resources:

kubectl apply -f config/samples/

2. Build and push your image to the location specified by IMG:

make docker-build docker-push IMG=<some-registry>/gitops-controller:tag

3. Deploy the controller to the cluster with the image specified by IMG:

make deploy IMG=<some-registry>/gitops-controller:tag

Uninstall CRDs

To delete the CRDs from the cluster:

make uninstall

Undeploy controller

UnDeploy the controller to the cluster:

make undeploy

Contributing

This is a just a toy project but any contributions are welcome.

How it works

This project aims to follow the Kubernetes Operator pattern

It uses Controllers which provides a reconcile function responsible for synchronizing resources untile the desired state is reached on the cluster

Test It Out

1. Install the CRDs into the cluster:

make install

2. Run your controller (this will run in the foreground, so switch to a new terminal if you want to leave it running):

make run

NOTE: You can also run this in one step by running: make install run

Modifying the API definitions

If you are editing the API definitions, generate the manifests such as CRs or CRDs using:

make manifests

NOTE: Run make --help for more information on all potential make targets

More information can be found via the Kubebuilder Documentation

License

Copyright 2022.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.