How to Set Up Argo CD on Kubernetes

Argo CD is a Kubernetes-native declarative GitOps tool for deploying large-scale applications on Kubernetes. It is lightweight, handy, and user-focused compared to other continuous delivery tools. In addition, it can pull application code directly from a Git repository and deploy it to a Kubernetes cluster. It supports different configuration management options, such as YAML, Kustomize, Jsonnet, Helm, and so on. Argo CD has a built-in web UI where you can monitor synchronizations and the application's state.

In this article, you will install Argo CD on your Kubernetes cluster, access its web UI, and deploy applications using Argo CD UI and Argo CD CLI.

Prerequisites

Before you start, you need to:

• Have access to a Kubernetes cluster with at least three nodes.
• Have access to a Linux-based local or remote instance to test the Argo CD CLI tool.
• Install and configure the kubectl CLI on your local machine.
• Install the Helm client on your local machine.
• A domain name to use with your Argo CD installation. For example, argo.example.com.

Install Argo CD

1. Create a namespace for Argo CD.

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   $ kubectl create namespace argocd

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2. In your home directory, create a new directory for Argo CD.

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   $ mkdir ~/argocd

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3. Navigate to the argocd directory.

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   $ cd ~/argocd

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4. Clone the Argo CD Helm repository.

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   $ git clone https://github.com/argoproj/argo-helm.git

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5. Navigate to the argo-cd directory of this repository.

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   $ cd argo-helm/charts/argo-cd/

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6. Update Helm dependencies.

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   $ helm dependency up

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7. Using Helm, install Argo CD in the argocd namespace.

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   $ helm install argocd . -f values.yaml -n argocd

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   When successful, you get an output with metadata about your installation.

   NAME: argocd
   LAST DEPLOYED: Sun Jun 11 18:13:17 2023
   NAMESPACE: argocd
   STATUS: deployed
   ...

8. Verify that Argo CD is deployed to the argocd namespace.

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   $ kubectl get pods -n argocd

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   The output should display a list of pods with names starting with argocd-, representing the various ArgoCD components.

9. Use the following command to get information about all running services and ports.

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   $ kubectl get services -n argocd

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   Output:

   NAME                               TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)             AGE
   ...
   argocd-server                      ClusterIP   10.101.247.167   <none>        80/TCP,443/TCP      53s

   The argocd-server service serves the Argo CD UI.

Access the Argo CD UI

At this point, Argo CD is installed and running. However, the Argo CD UI is not accessible outside the Kubernetes cluster. You can use port forwarding to expose the argocd-server service port to a port on your localhost. This way, you can access Argo CD without exposing the service to the external network.

1. Extract the default admin account password stored in a secret named argocd-initial-admin-secret.

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   $ kubectl get secrets -n argocd argocd-initial-admin-secret -o yaml

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   The encrypted password should display in your output as below.

   apiVersion: v1
   data:
     password: TU1DaWRNQVJXNWJ3S1FBNA==
   kind: Secret
   ...

   In the above output, TU1DaWRNQVJXNWJ3S1FBNA== is the admin account password. Copy the encrypted password to your clipboard for decoding.

2. Decode the password.

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   $ echo TU1DaWRNQVJXNWJ3S1FBNA== | base64 --decode

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   Copy the output.

3. Using kubectl, forward the port 443 of the argocd-server service to port 8080 of your localhost.

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   $ kubectl port-forward svc/argocd-server -n argocd 8080:443

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   Your output should look like the one below.

   Forwarding from 127.0.0.1:8080 -> 8080
   Forwarding from [::1]:8080 -> 8080

   This command will occupy your current terminal session.

4. Open the URL http://127.0.0.1:8080 on a web browser on your local machine to access the Argo CD UI.

   http://127.0.0.1:8080

   

5. Enter admin as the username, paste the password you decoded earlier, and click the Sign In button.

   You are redirected to the Argo CD dashboard if the credentials are correct.

   

Optional: Access Argo CD using the CLI Tool

Argo CD also offers a CLI tool that lets you deploy the application and enables other tasks, including syncing, refreshing, and pausing the Argo CD application as described in this section. Keeping the port forward command from the last section active in one terminal, open a new terminal and follow the below steps:

1. Using the wget utility, download the latest Argo CD CLI tool.

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   $ wget https://github.com/argoproj/argo-cd/releases/download/v2.7.4/argocd-linux-amd64

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   This command installs the version 2.7.4. You can get the latest version from the Assets section of the official GitHub repository page.

2. Move the downloaded binary to the system-wide directory /usr/local/bin/ that stores executable binaries.

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   $ sudo mv argocd-linux-amd64 /usr/local/bin/argocd

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3. Grant execute permissions on the Argo CD binary.

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   $ sudo chmod +x /usr/local/bin/argocd

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4. Use the argocd login command to log in to the Argo CD server.

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   $ argocd login localhost:8080

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   Accept the server certificate, then enter the username admin and the decoded password, as shown below.

   WARNING: server certificate had error: x509: certificate signed by unknown authority. Proceed insecurely (y/n)? y
   Username: admin
   Password: 

   When logged in, your output should look like the one below.

   'admin:login' logged in successfully
   Context 'localhost:8080' updated

5. To tighten server security, change the default password of your Argo CD installation.

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   $ argocd account update-password

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   It prompts you to enter your existing password, a new strong password, and confirm the new password.

Deploy Argo CD Applications

You can create and deploy Argo CD applications in multiple ways — using YAML files, the Argo CD UI, or the Argo CD CLI. In this section, you'll deploy two Argo CD applications to your cluster, one using a YAML file and the other via the Argo CD UI.

Creating and Deploying an Application Using YAML Manifest File

1. Create a YAML file for your application.

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   $ nano argocd-app.yaml

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   Add the following configuration.

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   apiVersion: argoproj.io/v1alpha1
   kind: Application
   metadata:
     name: argo-application
     namespace: argocd
   spec:
     project: default
     source:
       repoURL: https://gitlab.com/jasmine.harit/argocd-app-config.git
       targetRevision: HEAD
       path: dev
     destination: 
       server: https://kubernetes.default.svc
       namespace: myapp
     syncPolicy:
       syncOptions:
       - CreateNamespace=true
       automated:
         selfHeal: true
         prune: true

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   Save and close the file

2. Apply the YAML configuration.

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   $ kubectl apply -f argocd-app.yaml

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3. Verify the deployment status of the application.

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   $ kubectl get app -n argocd

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   Output:

   NAME               SYNC STATUS   HEALTH STATUS
   argo-application   Synced        Healthy

   You can also verify the deployment using the Argo CD CLI tool.

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   $ argocd app list

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   Output:

   NAME                     CLUSTER                         NAMESPACE  PROJECT  STATUS  HEALTH   SYNCPOLICY  CONDITIONS       REPO                                                    PATH  TARGET
   argocd/argo-application  https://kubernetes.default.svc  myapp      default  Synced  Healthy  Auto-Prune  <none>      https://gitlab.com/jasmine.harit/argocd-app-config.git  dev   HEAD

4. To get detailed information on your application, run the following command.

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   $ argocd app get argo-application

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   Output:

   Name:               argocd/argo-application
   Project:            default
   Server:             https://kubernetes.default.svc
   Namespace:          myapp
   URL:                https://localhost:8080/applications/argo-application
   Repo:               https://gitlab.com/jasmine.harit/argocd-app-config.git
   Target:             HEAD
   Path:               dev
   SyncWindow:         Sync Allowed
   Sync Policy:        Automated (Prune)
   Sync Status:        Synced to HEAD (9c92bf8)
   Health Status:      Healthy
   
   GROUP  KIND        NAMESPACE  NAME           STATUS   HEALTH   HOOK  MESSAGE
          Namespace              myapp          Running  Synced         namespace/myapp created
          Service     myapp      myapp-service  Synced   Healthy        service/myapp-service created
   apps   Deployment  myapp      myapp1         Synced   Healthy        deployment.apps/myapp1 created

5. In your web browser session, refresh the dashboard to view the deployed Argo CD application as below.

   http://127.0.0.1:8080

   

Create and Deploy Applications using the Argo CD Dashboard and CLI Tool

1. Load the Argo CD UI dashboard. Click the NEW APP to view the Application configuration screen.

   

   • In the GENERAL section, define your application name, project, and sync policy.
   • Within the SOURCE section, enter the application repository's path, revision, and URL. For instance, you can use the argocd-example-apps repository as the Source and choose any of its applications in the Path option, such as the helm-guestbook application.

   

   • In the DESTINATION section, enter your cluster URL and namespace.
   • Click CREATE to deploy the application. When the application deployment finishes, the following screen should display.

   

   Using the Argo CD CLI, run the following command to check the status of your deployed application.

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   $ argocd app get guestbook

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   Output:

   Name:               argocd/guestbook
   Project:            default
   Server:             https://kubernetes.default.svc
   Namespace:          argocd
   URL:                https://argocd.example.com/applications/guestbook
   Repo:               https://github.com/argoproj/argocd-example-apps.git
   Target:             HEAD
   Path:               helm-guestbook
   SyncWindow:         Sync Allowed
   Sync Policy:        <none>
   Sync Status:        OutOfSync from HEAD (4773b9f)
   Health Status:      Missing
   
   GROUP  KIND        NAMESPACE  NAME                      STATUS     HEALTH   HOOK  MESSAGE
          Service     argocd     guestbook-helm-guestbook  OutOfSync  Missing        
   apps   Deployment  argocd     guestbook-helm-guestbook  OutOfSync  Missing 

   As displayed in the above output, the application is deployed but the status is OutofSync. To sync it, run the following command.

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   $ argocd app sync guestbook

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   The above command fetches the necessary manifests from the application repository and uses kubectl to configure it.

2. On the Argo CD web dashboard, verify the health status of your application.

3. Click the application to view more information about it.

   

Secure Argo CD with TLS Encryption

This section covers the steps to expose your Argo CD server using Nginx Ingress controller, terminated using TLS encryption.

1. Install Nginx Ingress controller on your cluster.

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   $ helm install my-ingress-nginx ingress-nginx \
   --repo https://kubernetes.github.io/ingress-nginx \
   --namespace ingress-nginx --create-namespace

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   This command installs the Nginx Ingress controller in a new Namespace ingress-nginx and names its resources starting with my-ingress-nginx-.

2. Check the Ingress Services to get the Load balancer IP address.

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   $ kubectl get services -n ingress-nginx

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   Output:

   NAME                                    TYPE           CLUSTER-IP     EXTERNAL-IP    PORT(S)                      AGE
   my-ingress-nginx-controller             LoadBalancer   10.97.77.219   192.0.2.10     80:31808/TCP,443:30834/TCP   5m50s
   my-ingress-nginx-controller-admission   ClusterIP      10.108.64.48   <none>         443/TCP                      5m50s

   Take note of the EXTERNAL-IP value of the my-ingress-nginx-controller service, and create a domain A DNS record for your domain, such as argo.example.com.

   Note

   The service my-ingress-nginx-controller may take some time to get its EXTERNAL-IP value. Until it gets it, its value is displayed as <pending>. Give it some time to get its value.

3. Install cert-manager.

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   $ kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.17.2/cert-manager.yaml

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   This command installs the v1.17.2 version of cert-manager on your cluster in cert-manager namespace. You can get the latest version of cert-manager from its official releases page.

4. Create a manifest file to provision an Issuer resource.

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   $ nano issuer.yaml

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5. Add the following content to the file.

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   apiVersion: cert-manager.io/v1
   kind: Issuer
   metadata:
     name: tls-certificate-issuer
     namespace: default
   spec:
     acme:
       server: https://acme-v02.api.letsencrypt.org/directory
       email: admin@example.com
       privateKeySecretRef:
         name: letsencrypt-private-key
       solvers:
         - http01:
             ingress:
               class: nginx

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   Replace admin@example.com with your email address. Otherwise the Issuer will not work.

   Save and exit the file.

6. Create a manifest file to provision the Ingress resource for the argocd-server service.

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   $ nano ingress.yaml

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7. Add the following content to the file.

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   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     name: ingress-argocd
     namespace: argocd
     annotations:
       cert-manager.io/issuer: tls-certificate-issuer
   spec:
     ingressClassName: nginx
     rules:
     - host: argo.example.com
       http:
         paths:
         - pathType: Prefix
           path: "/"
           backend:
             service:
               name: argocd-server
               port:
                 number: 80
     tls:
     - hosts:
         - argo.example.com
       secretName: argocd-tls

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   Save and exit the file.

8. Check the tls certificate.

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   $ kubectl get certificate -n argocd

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   Output:

   NAME         READY   SECRET       AGE
   argocd-tls   False   argocd-tls   5m43s

   After sometime, the status of the certificate changes to True.

9. Verify the configuration by visiting your domain name https://argo.example.com in a web browser.

Conclusion

You have installed Argo CD on a Kubernetes cluster and explored how to deploy applications using the Argo CD UI, Argo CD CLI, and using YAML configuration files. For more information about Argo CD, please visit the official documentation.