Skip to content

Latest commit

 

History

History
175 lines (112 loc) · 6.62 KB

README.md

File metadata and controls

175 lines (112 loc) · 6.62 KB
Raw

demo-kubebuilder

Description

Let’s do a little exercise: we’ll build a simple foo operator which has no real use, except to demonstrate the capabilities of an operator. Our operator will manage the CRD named PodFriend. We fetch the PodFriend resource that triggered the reconciliation request to get the name. Then, we list all the pods that have the same name as PodFriend. If we find one (or more), we update PodFriend's happy status to true, else we set it to false.

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.

Create an operator

kubebuilder init --domain my.company --repo my.company/demo

The kubebuilder init --domain my.company --repo my.company/demo command is used to initialize a new controller (operator) project in Kubernetes using Kubebuilder, which is a tool for building Kubernetes controllers and operators.

The meaning of each part of the command is explained in detail below:

kubebuilder startup This is the main command to initialize a new project with Kubebuilder. Create the basic structure of the project, including the directories and files necessary to begin developing a controller.

--domain my.company The --domain option specifies the domain to use in the API Group of the Custom Resource Definitions (CRDs) that you will create with this operator. This domain is used to construct the full name of the API group, for example, if you have a MyResource resource in the apps group, the full group could be myresource.apps.my.operator.

--repo my.domain/tutorial

The --repo option defines the Go module (the Go module path) to use for the project. This is important because Go uses the module name to manage project dependencies. In this case, my.domain/tutorial will be the name of the Go module. This also sets the base import path for your project, which is important for Go to find packages correctly.

Practical example

Let's break down what happens when you run this command:

Project Initialization: A directory and file structure is created that Kubebuilder uses to manage the development of the operator. This includes files like go.mod, main.go and directories like api and drivers.

Domain: The my.operator domain will be used to generate the full name of the API groups of your CRDs. For example, if you define a resource in the apps group, the group's distinguished name will be apps.my.company.

Repository/Go Module: The Go module my.domain/tutorial is set in the project's go.mod file, which sets up the Go development environment for your operator. This is crucial for dependency management and for Go tools to know how to import and compile your code.

Create a API

kubebuilder create api --group operator --version v1 --kind PodFriend

Structure

image

  • api/: Directory where you define your CRDs and API versions.

  • controllers/: Directory where you define the controllers that manage your resources.

  • config/: Contains configuration files for deploying your operator to Kubernetes.

  • go.mod: Go modules file that contains the module name my.company/demo and project dependencies.

  • main.go: Entry point of the application, where the controller manager is configured and started.

Reproduce the scenarios

  • cd

  • make manifests

  • make install

  • make run

  • kubectl get podfriends (check that there aren't podfriends)

  • kubectl apply -f ./config/samples/operator_v1_podfriend.yaml #Create 2 podfriends

  • kubectl describe pod <podfriend> #Show that the podfriend has status false

  • kubectl run <name_pod_friend> --image=nginx #Use the name of podfriend that you have

  • Check the status of podFriends, one of them must has the status in true.

  • Delete the pod. check the podfriend, the status must be in false.

To Deploy on the cluster

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

make docker-build docker-push IMG=<some-registry>/demo-kubebuilder: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>/demo-kubebuilder: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>/demo-kubebuilder: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.

  1. Using the installer

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

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

Contributing

// TODO(user): Add detailed information on how you would like others to contribute to this project

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.