I recently got started with Kubernetes Operators on Openshift 4.1 . A lot of lessons learned but have more to learn.

What are Operators

Kubernetes Operator are a way of leveraging the Kubernetties API to create your own Kubernetes custom resources.

The project I am working on Integreatly is using the Operator-sdk framework to build operators, this takes some of the complexity out of building a Kubernetes Operators.

I won't go into installing a operator that's documented in the Operator-sdk docs.

Running locally

You can run the operator-sdk locally, and point it at the namespace for your operator

operator-sdk up local --namespace=integreatly-operator

NOTE: command changed with v0.15.0 operator-sdk run --local --namespace=integreatly-operator

What this means that instead of having to build a container image and push it to a app registry like quay.io or dockerhub.com, you can just use your local code base as the source instead of a container image and use it to deploy your operator to your Openshift 4 cluster.

Setup Vscode to debug

I use Vscode so how do I debug using operator-sdk up local?

Delve is a debug tool for golang, it can be downloaded here https://github.com/go-delve/delve/tree/master/Documentation/installation or by just using go

go get -u github.com/go-delve/delve/cmd/dlv 

Delve is used by this Vscode Go plugin https://marketplace.visualstudio.com/items?itemName=ms-vscode.Go

You need to run delve with the command line switch --enable-delve on the up local command
e.g. The operator I am working on is called integreatly-operator so the commands to run it are as follows

# You need to set the namespace to watch 
$ export WATCH_NAMESPACE=integreatly-operator
# You can then run the up local with delve enabled
$ operator-sdk up local --namespace=integreatly-operator --enable-delve
# you will see something like
INFO[0000] Running the operator locally.                
INFO[0000] Using namespace integreatly-operator.        
INFO[0000] Delve debugger enabled with args [--listen=:2345 --headless=true --api-version=2 exec build/_output/bin/integreatly-operator-local --] 
API server listening at: [::]:2345

NOTE: WATCH_NAMESPACE should always point to the namespace for your operator

You will need a launch json for Vscode to interact with this headless mode of delve

{
    "version": "0.2.0",
    "configurations": [
      {
        "name": "Integreatly Operator",
        "type": "go",
        "request": "launch",
        "mode": "auto",
        "program": "${workspaceFolder}/cmd/manager/main.go",
        "env": {
          "WATCH_NAMESPACE": "integreatly-operator"
        },
        "args": []
      }
    ]
  }

Start the vscode debugger. Open the Debug console and you will see the standard output from the operator-sdk up local command, Your debugger will stop on the set breakpoints.