Jenkins deployment with Kustomize - how to add JENKINS_OPTS

Question

I feel like this should be an already asked question, but I'm having difficulties finding a concrete answer. I'm deploying Jenkins through ArgoCD by defining the deployment via kustomize (kubernetes yaml). I want to inject a prefix to have Jenkins start on /jenkins, but I don't see a way to add it. I saw online that I can have a env tag, but no full example of this was available. Where would I inject a prefix value if using kubernetes yaml for a Jenkins deployment?

Answer 1

So, I solved this issue myself, and I'd like to post the answer as this is the top searched question when searching "Kustomize Jenkins_opts".

In your project, assuming you are using Kustomize to deploy Jenkins (This will work with any app deployment where you want to inject values when deploying), you should have a project structure similar to this:

ProjectA
|
|---> app.yaml //contains the yaml definitions for your deployment
|---> kustomize.yaml //entry file to run Kustomize to deploy your app

Add a new file to your project structure. Name it whatever you want, I named mine something like app-env.yaml. It will look something like:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: jenkins
spec:
  template:
    spec:
      containers:
        - name: jenkins
          env:
            - name: JENKINS_OPTS
              value: --prefix=/jenkins

This will specifically inject the --prefix flag to assign the prefix value for the URL to Jenkins on deployment to the Jenkins container. You can add multiple env variables. You can inject any value you want. My example is using Jenkins specific flags as this question centered around Jenkins, but it works for any app. Add this file to your Kustomize file from earlier:

namePrefix: kustomize-

resources:
- app.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

patchesStrategicMerge:
- app-env.yaml

When your app is deployed via K8s, it will run the startup process for your app, while passing the values defined in your env file. Hope this helps anyone else.