GitOps with ArgoCD on K3s

Summary

For my ServiceNow readers, this post will not touch on ServiceNow but if you like Kubernetes and are interested in Continuous Deployment, read on! First of all, What is GitOps? Essentially it means managing your infrastructure using infrastructure as code, more specifically through Git repositories. This ensures a single source of truth for your infrastructure. ArgoCD is an open source project for automating your Kubernetes Deployments. ArgoCD will poll the GitRepo associated to your Kubernetes application and automatically deploy the changes to the target Kubernetes cluster. If there is a deployment issue it will auto rollback the change.

Setting up ArgoCD on K3s

First we need a K3s instance. On your linux server run the K3s installer if you haven’t already.

sudo curl -sfL https://get.k3s.io | K3S_KUBECONFIG_MODE="644" sh -

Now we can install ArgoCD. It installs into the cluster and does not use PVCs. All data is stored in etcd. Run this script below. It will create the ArgoCD instance and supply the default admin password.

Once completed you can login to http://hostIPorName/argocd

Adding an App to ArgoCD

Now we are ready to create an app - https://argo-cd.readthedocs.io/en/stable/getting_started/

First we need to install the argocd CLI

sudo curl -sSL -o /usr/local/bin/argocd https://github.com/argoproj/argo-cd/releases/latest/download/argocd-linux-amd64
sudo chmod +x /usr/local/bin/argocd

Now we can login

ip=`hostname -i` #get IP from host and use generated password collected earlier
argocd login $ip --grpc-web --grpc-web-root-path argocd --insecure --username admin --password $defaultPass

Finally we can create our app. You will also be able to see this in the web ArgoCD web interface

argocd app create nginxweb --repo https://github.com/mtcoffee/argocd-example-apps.git --path nginxweb --dest-server https://kubernetes.default.svc --dest-namespace default
argocd app sync nginxweb

Just like that ArgoCD has automatically deployed our application from the github repo. Open http://hostIPorName/web to see the resulting Nginx deployment.

Now if you want to have some fun, clone the example repo and change the HTML in the config map. Within 3 minutes ArgoCD will automatically update the app with your new html.

Bonus Guestbook app

There are some sample applications in the official Kubernetes repo. Try out the guestbook app.

argocd app create guestbook-go --repo https://github.com/kubernetes/examples.git --path guestbook-go --dest-server https://kubernetes.default.svc --dest-namespace default
argocd app sync guestbook-go

##the example repo is broken and needs a Service for redis
kubectl apply -f - << "EOF"
kind: Service
apiVersion: v1
metadata:
  name: redis-slave
  labels:
    app: redis
    role: replica
spec:
  ports:
    - port: 6379
      targetPort: redis-server
  selector:
    app: redis
    role: replica
EOF

Now visit your new guestbook! http://hostIPorName:3000/