Steps to generate CRD/Operator code

[devdattakulkarni]

Here are the steps that one needs to follow towards generating your own CRD/Operator code.

Generating Client/Listers/Informers:

For generating the client/listers/informers, etc. the first step is to create specific directory structure and define specific files in it. Here is that structure and the required files:

• pkg/apis/some-controller-name/register.go
• pkg/apis/some-controller-name/v1/doc.go
• pkg/apis/some-controller-name/v1/types.go
• pkg/client
• pkg/signals

Following are detailed steps:

1. Choose a name for your CRD's group name -- say 'postgrescontroller'

2. Create pkg/apis/'CRD group name' directory

3. cd pkg/apis/'CRD group name'

4. Inside this directory create register.go to register the group name. When registering the name, choose some qualifier (example, in
   https://github.com/cloud-ark/kubeplus/blob/master/postgres-crd-v2/pkg/apis/postgrescontroller/register.go we have used "kubeplus" as the qualifier name.).

5. Create v1 directory inside pkg/apis/'CRD group name'

6. cd pkg/apis/'CRD group name'/v1

7. Create doc.go. Make sure you set the "+groupName=." in line 20 of doc.go. Leave line 21 as it is. See https://github.com/cloud-ark/kubeplus/blob/master/postgres-crd-v2/pkg/apis/postgrescontroller/v1/doc.go

8. Copy https://github.com/cloud-ark/kubeplus/tree/master/operator manager/pkg/apis/operatorcontroller/v1/register.go into pkg/apis//v1/.
   Make appropriate changes to this file.

9. Define your CRD spec in types.go

10. Nothing else needs to be created in the pkg/apis directory

11. Create pkg/client directory. Nothing needs to be created inside the client directory -- leave it empty.

12. Create pkg/signals directory and just copy all the files from https://github.com/cloud-ark/kubeplus/tree/master/postgres-crd-v2/pkg/signals into pkg/signals.
    You don't need to modify anything in any of these files.

13. Go inside the hack/ directory.

14. Edit update-codegen.sh to include the path of your folder

15. Copy Gopkg.lock and Gopkg.toml from
    https://github.com/cloud-ark/kubeplus/tree/master/operator-manager

16. Install Go dependencies
    dep ensure (this will create the vendor folder)

17. mkdir vendor/k8s.io/code-generator/hack

18. cp hack/boilerplate.go.txt vendor/k8s.io/code-generator/hack/.

19. From the main directory of your CRD code execute following:
    ./hack/update-codegen.sh

Running the controller:

1. In the controller.go (and other go files), include the CRD client/listers/informers etc. with appropriate path. See https://github.com/cloud-ark/kubeplus/blob/master/postgres-crd-v2/controller.go#L47 for an example.

2. go run *.go -kubeconfig=$HOME/.kube/config

Reference:

kubernetes/sample-controller#13

[chrisduong]

I had followed this guide. It really WORKS! Thanks!

[devdattakulkarni]

@chrisduong 👍

[devdattakulkarni]

Close this issue after moving the steps in docs.

[devdattakulkarni]

Steps to create custom Kubernetes controller based on the https://github.com/kubernetes/sample-controller (July 27, 2022)

Uses go modules.

1] export GO111MODULE=on
2] mkdir your-controller
3] cd your-controller
4] copy go.mod, go.sum, hack from https://github.com/kubernetes/sample-controller to your-controller
5] Modify module name in go.mod as you see fit
6] Modify hack/update-codegen.sh as follows:

  bash "${CODEGEN_PKG}"/generate-groups.sh "deepcopy,client,informer,lister" \
  <your-module-name>/pkg/generated <your-module-name>/pkg/apis \
  "<your-group>:<your-version>" -v 10 \
   #  --output-base $output_base \
   #  --go-header-file "${SCRIPT_ROOT}"/hack/boilerplate.go.txt

7] Create your type definitions in your-controller/pkg (See sample-controller/pkg for reference. You have to create the apis folder sub-tree manually. Create empty 'generated' sub-folder. Copy signals from sample-controller/pkg/signals).
8] go mod vendor
9] mkdir vendor/k8s.io/code-generator/hack
10] cp hack/boilerplate.go.txt vendor/k8s.io/code-generator/hack/.
11] ./hack/update-codegen.sh
12] Write your controller go code
13] go mod vendor (get dependencies)
14] go build . (use vendored dependencies)

[zffocussss]

I can not believe it!