kubernetes-controller

This Kubernetes controller watches for MyCrd type resource creation, whenever the resource is created, corresponding pods are created based on the specs of MyCrd.

Description

This controller creates a Crd as MyCrd. MyCrd resource has properties:

spec:
  podName: my-pod
  imageName: nginx
  podNamespace: default
  podCount: 2

• The above parameters are used by the controller reconciler to create pods with parameters podName: my-pod, imageName: nginx, and in namespace podNamespace: default, the count of pods is defined by podCount: 2.

• The pods created will have a naming convention <podName>-0, <podName>-1 and so on.

• If pods are already existing in given namespace, pods will not be created.

• If the pods are deleted, reconciler will recreate them.

• Reconciler has a requeue duration of 8sec. Reconcilation takes 8sec.

• MyCrd resource keeps the status of the pods created. If the availablePods are less than desired, state will be Pending.

NAME            STATUS
mycrd-sample    Success
mycrd-sample2   Pending

status:
  availablePods: 1
  conditions:
  - state: Pending

Getting Started

Prerequisites

• go version v1.21.0+
• docker version 17.03+.
• kubectl version v1.11.3+.
• Access to a Kubernetes v1.11.3+ cluster.

To Deploy on the cluster

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

make docker-build docker-push IMG=<some-registry>/kubernetes-controller-2:tag

NOTE: This image ought to be published in the personal registry you specified. And it is required to have access to pull the image from the working environment. Make sure you have the proper permission to the registry if the above commands don’t work.

Install the CRDs into the cluster:

make install

Deploy the Manager to the cluster with the image specified by IMG:

make deploy IMG=<some-registry>/kubernetes-controller-2:tag

NOTE: If you encounter RBAC errors, you may need to grant yourself cluster-admin privileges or be logged in as admin.

Create instances of your solution You can apply the samples (examples) from the config/sample:

kubectl apply -k config/samples/

NOTE: Ensure that the samples has default values to test it out.

To Uninstall

Delete the instances (CRs) from the cluster:

kubectl delete -k config/samples/

Delete the APIs(CRDs) from the cluster:

make uninstall

UnDeploy the controller from the cluster:

make undeploy

Project Distribution

Following are the steps to build the installer and distribute this project to users.

1. Build the installer for the image built and published in the registry:

make build-installer IMG=<some-registry>/kubernetes-controller-2:tag

NOTE: The makefile target mentioned above generates an 'install.yaml' file in the dist directory. This file contains all the resources built with Kustomize, which are necessary to install this project without its dependencies.

2. Using the installer

Users can just run kubectl apply -f to install the project, i.e.:

kubectl apply -f https://raw.githubusercontent.com/<org>/kubernetes-controller-2/<tag or branch>/dist/install.yaml

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

More information can be found via the Kubebuilder Documentation

License

Copyright 2024.

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.