Docker / Kubernetes - ArgoCD on Kubernetes cluster

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Introduction

ArgoCD follows the GitOps pattern of using Git repositories as the source of truth for defining the desired application state. In other words, the ArgoCD automatically synchronize the cluster to the desired state defined in a Git repository.

Each workload is defined declarative through a resource manifest in a YAML file. Argo CD checks if the state defined in the Git repository matches what is running on the cluster and synchronizes it if changes were detected.

Kubernetes manifests can be specified in several ways:

Kustomize applications
Helm Charts
Plain directory of YAML/json manifests

In this post, we'll use #3 (simple yamls) and they will be deployed to a Minikube cluster.

Installing ArgoCD and accessing ArgoCD API Server

ArgoCD project can be found at https://github.com/argoproj/argo-cd.

Create a separate namespace for ArgoCD:

$ kubectl create namespace argocd
namespace/argocd created  

$ kubectl get ns
NAME              STATUS   AGE
argocd            Active   3s
default           Active   4d19h
kube-node-lease   Active   4d19h
kube-public       Active   4d19h
kube-system       Active   4d19h

Then, we can install ArgoCD into the argocd namespace:

$ kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/master/manifests/install.yaml

$ kubectl get all -n argocd
NAME                                     READY   STATUS    RESTARTS   AGE
pod/argocd-application-controller-0      1/1     Running   0          34m
pod/argocd-dex-server-567b48df49-4dd7p   1/1     Running   0          34m
pod/argocd-redis-6fb68d9df5-xs4rz        1/1     Running   0          34m
pod/argocd-repo-server-6dcbd9cb-8nhmp    1/1     Running   0          34m
pod/argocd-server-69678b4f65-xrddw       1/1     Running   0          34m

NAME                            TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)                      AGE
service/argocd-dex-server       ClusterIP   10.110.134.70   <none>        5556/TCP,5557/TCP,5558/TCP   34m
service/argocd-metrics          ClusterIP   10.104.185.89   <none>        8082/TCP                     34m
service/argocd-redis            ClusterIP   10.111.92.240   <none>        6379/TCP                     34m
service/argocd-repo-server      ClusterIP   10.100.192.39   <none>        8081/TCP,8084/TCP            34m
service/argocd-server           ClusterIP   10.99.48.85     <none>        80/TCP,443/TCP               34m
service/argocd-server-metrics   ClusterIP   10.103.236.26   <none>        8083/TCP                     34m

NAME                                 READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/argocd-dex-server    1/1     1            1           34m
deployment.apps/argocd-redis         1/1     1            1           34m
deployment.apps/argocd-repo-server   1/1     1            1           34m
deployment.apps/argocd-server        1/1     1            1           34m

NAME                                           DESIRED   CURRENT   READY   AGE
replicaset.apps/argocd-dex-server-567b48df49   1         1         1       34m
replicaset.apps/argocd-redis-6fb68d9df5        1         1         1       34m
replicaset.apps/argocd-repo-server-6dcbd9cb    1         1         1       34m
replicaset.apps/argocd-server-69678b4f65       1         1         1       34m

NAME                                             READY   AGE
statefulset.apps/argocd-application-controller   1/1     34m

Once the pods are ready, ArgoCD will be running. But the ArgoCD API server will not be accessible from outside the cluster. We'll use port-forward to expose a port to the service, and forward it to localhost:

$ kubectl port-forward svc/argocd-server -n argocd 8080:443  
Forwarding from 127.0.0.1:8080 -> 8080
Forwarding from [::1]:8080 -> 8080

Now we'll be able to access the API server via localhost:8080:

The username for Argo CD is admin and the initial password is autogenerated. The initial password is usually the pod name of the Argo CD server:

$ kubectl get pod -n argocd
NAME                                 READY   STATUS    RESTARTS   AGE
argocd-application-controller-0      1/1     Running   0          6m7s
argocd-dex-server-567b48df49-4dd7p   1/1     Running   0          6m9s
argocd-redis-6fb68d9df5-xs4rz        1/1     Running   0          6m9s
argocd-repo-server-6dcbd9cb-8nhmp    1/1     Running   0          6m8s
argocd-server-69678b4f65-xrddw       1/1     Running   0          6m8s

So, in our case, username = admin and password = argocd-server-69678b4f65-xrddw. Login with the credentials.

Creating an app on ArgoCD

Now we want to create an application for our project on ArgoCD.

After the login, click the Manage your repositories in the left panel:

Then click Repositories.

We can use either HTTPS or SSH link to connect our repository to ArgoCD:

For a public repository, we just add the repo URL:

It's pointing to the githubrepo:

Click "Connect":

Once connected to the github, go the "Application":

Fill out the necessary fields:

Once we filled all the required details, click "CREATE" and we'll be able to see our application:

Click the "OutOfSync" and we see the details:

Click the "SYNC" and we'll get an output below, and then click "SYNCHRONIZE":

It will start syncing and it takes some time to complete the process. Once i'’s done our app should look like this:

$ kubectl get all
NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-6799fc88d8-4zx8w   1/1     Running   0          6m32s

NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
service/kubernetes   ClusterIP   10.96.0.1      <none>        443/TCP        16h
service/nginx        NodePort    10.96.35.252   <none>        80:31555/TCP   6m33s

NAME                    READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nginx   1/1     1            1           6m32s

NAME                               DESIRED   CURRENT   READY   AGE
replicaset.apps/nginx-6799fc88d8   1         1         1       6m32s

Now that our pod and service are in place, let's access the nginx app:

$ minikube service nginx
|-----------|-------|-------------|-------------------------|
| NAMESPACE | NAME  | TARGET PORT |           URL           |
|-----------|-------|-------------|-------------------------|
| default   | nginx |          80 | http://172.17.0.3:31555 |
|-----------|-------|-------------|-------------------------|
  Starting tunnel for service nginx.
|-----------|-------|-------------|------------------------|
| NAMESPACE | NAME  | TARGET PORT |          URL           |
|-----------|-------|-------------|------------------------|
| default   | nginx |             | http://127.0.0.1:64462 |
|-----------|-------|-------------|------------------------|
  Opening service default/nginx in default browser...
  Because you are using a Docker driver on darwin, the terminal needs to be open to run it.

We may want to play more since there are lots of additional features. For example, in the demo, we used "Manual" sync policy but we want to try "Automatic" sync policy as well!