GitOps way with Github Actions and self-hosted runner on Kubernetes

In this tutorial, I will show how to:

Deploy self-hosted-runner to Kubernetes and connect it with your GitHub repo.
Redeploy Nginx server on your k8s cluster with every change in nginx/deployment.yaml, which pushed to Github repo.

“Every change in configuration of deployment.yaml on Github will be propagated to Nginx server.”

Github Actions published guides:

So, why self-hosted runner?

The reason for self-hosted runner is coming from security limitation ( in my case), I have an internal k8s cluster which is not externally reachable and can be accessed only via VPN.

So how it works if the cluster can’t be reached externally?

Communication between self-hosted runners and GitHub

The self-hosted runner connects to GitHub to receive job assignments and to download new versions of the runner application. The self-hosted runner uses an HTTPS long poll that opens a connection to GitHub for 50 seconds, and if no response is received, it then times out and creates a new long poll. The application must be running on the machine to accept and run GitHub Actions jobs. Since the self-hosted runner opens a connection to GitHub.com, you do not need to allow GitHub to make inbound connections to your self-hosted runner.

meaning self-hosted runner using https polling to talk with Github, but Github not talking directly with self-hosted runners.

Let’s do it

Need to generate Github’s Personal access token (PAT) first

Go to your Github account -> https://github.com/settings/profile, then to

Developer settings -> Generate new token

Provision of self-hosted runner to k8s

I will use Dockerfile for self-hosted runner from this repo: Github self-hosted

by Sander Knape, https://sanderknape.com/2020/03/self-hosted-github-actions-runner-kubernetes/

Validation of PAT by running self-hosted runner as docker container

docker run --name github-runner \
     -e GITHUB_OWNER=warolv \
     -e GITHUB_REPOSITORY=github-actions-series \
     -e GITHUB_PAT=YOUR_GITHUB_PAT \
     sanderknape/github-runner

I am using my Github account for testing: warolv, repo is ‘github-actions-series’ and PAT we generated previously

Go to your Github repo -> settings -> Actions -> runners, you will see new self-hosted runner:

self-hosted runner is connected to Github and ready to do the job, looks good:-)

Next step will be to deploy it to k8s.

I will use my ‘kind’ k8s cluster for demo:

https://kind.sigs.k8s.io/

kind create cluster

Now let’s actually provision self-hosted runner to k8s

First clone my repo: git clone [email protected]:warolv/github-actions-series.git

Creating of k8s secret with PAT in namespace: ‘github-runner’

# create github-runner namespace
kubectl create ns github-runner

# create secret from PAT we got previously
kubectl create secret generic gh-pat \
    -n github-runner \
    --from-literal=pat=YOUR_GITHUB_PAT

Overview of manifests for deployment

gr-deployment.yaml (self-hosted-runner/gr-deployment.yaml in cloned repo)

apiVersion: apps/v1
kind: Deployment
metadata:
  name: github-runner
  namespace: github-runner
  labels:
    app: github-runner
spec:
  replicas: 1
  selector:
    matchLabels:
      app: github-runner
  template:
    metadata:
      labels:
        app: github-runner
    spec:
      serviceAccountName: gr-sa
      containers:
      - name: github-runner
        image: sanderknape/github-runner:latest
        env:
        - name: GITHUB_OWNER
          value: warolv
        - name: GITHUB_REPOSITORY
          value: github-actions-series
        - name: RUNNER_LABELS
          value: self-hosted-runner
        - name: GITHUB_PAT
          valueFrom:
            secretKeyRef:
              name: gh-pat
              key: pat
        lifecycle:
          postStart:
            exec:
              command: ["sh", "-c", "install kubectl..."]

For deployment of self-hosted runner to k8s, you need to set proper values for:

GITHUB_OWNER: warolv in my case
GITHUB_REPOSITORY: [ github-actions-series], for my demo
RUNNER_LABELS: [ self-hosted-runner ], used in workflow
GITHUB_PAT: taken from k8s secret we created previously

Also we installing ‘kubectl’ to existing runner using ‘lifecycle poststart’ hook, we need kubectl to redeploy Nginx on configuration change.

PostStart The PostStart hook is called immediately after a container is created. This occurs as it transitions into the Running phase after its Waiting period.

gr_sa.yaml is a service account which will be attached to runner, in order to have permissions for redeploying Nginx.

apiVersion: v1
kind: ServiceAccount
metadata:
  name: gr-sa
  namespace: github-runner

gr-cluster-role.yaml and gr-cluster-role-binding.yaml is a binding of needed permissions to ‘gr-sa’ service account.

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: pod-handler
rules:
- apiGroups: ["apps"]
  resources: ["pods", "deployments"]
  verbs: ["get", "list", "watch", "create", "update", "patch", "delete"]

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: pod-handler-binding
  namespace: github-runner
roleRef: 
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: pod-handler 
subjects:
- kind: ServiceAccount
  name: gr-sa
  namespace: github-runner

Let’s deploy all needed manifests in self-hosted-runner folder

kubectl apply -f self-hosted-runner

Validate self-hosted-runner is running and connected

kubectl get pods
github-runner-58855b59b6-l87sv   1/1     Running   0          165m

kubectl logs github-runner-58855b59b6-l87sv

Add Github Workflow to redeploy Nginx on configuration change

Last step actually would be to create workflow with Github Actions to redeploy Nginx server on configuration change, when nginx/deployment.yaml is changed, committed and pushed to repo.

.github/workflows/nginx_redeploy.yaml

name: Redeploy nginx after changes in deployment.yaml
on:
  push:
    paths:
      - nginx/**

jobs:
  redeploy-nginx:
    runs-on: self-hosted-runner
    steps:
      - uses: actions/checkout@v3
      - name: Redeploy nginx
        run: |
          kubectl apply -f nginx/deployment.yaml

I use ‘paths:’ to make sure Nginx will be redeployed only if nginx/deployment.yaml is changed.

To actually apply changes I use ‘kubectl apply -f nginx/deployment.yaml’, kubectl was installed into runner as I explained previously.

Now each commit with a change of nginx/deployment.yaml which pushed, will redeploy Nginx (In this example I changed number of replicas to 2 replicas) :

Thank you for reading, I hope you enjoyed it, see you in the next post.

I also will create Youtube video for this tutorial on my YT channel, please subscribe!

If you want to be notified when the next post of this tutorial is published, please follow me on medium and on my Twitter (@warolv).

You can get all tutorials of Gihub Action from my github repo by cloning it: ‘git clone https://github.com/warolv/github-actions-series.git‘

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