CI/CD on Kubernetes with Argo

Kubernetes has become the de facto standard for container orchestration and has been widely adopted by organizations of all sizes. With the rise in microservices, managing deployments and ensuring continuous integration and continuous delivery (CI/CD) has become critical aspects of software development. This is where ArgoCD comes in. In this blog, we will discuss how to perform CI/CD on a Kubernetes cluster using ArgoCD.

Methods of Deploying ArgoCD

ArgoCD is an open-source GitOps tool that helps automate application deployment in a Kubernetes cluster. To get started with ArgoCD, it needs to be installed in the cluster. There are several ways to install ArgoCD, including the usage of a command line interface (CLI), a YAML file, or an ArgoCD Operator.

Requirements

In this blog, we will install ArgoCD using the CLI. First, you need to have kubectl and a working Kubernetes cluster installed. Once you have the prerequisites, run the following command to install ArgoCD:

kubectl create namespace argocd
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

Deploying the App

Once ArgoCD is installed, you can deploy your app using ArgoCD. ArgoCD uses a Git repository to manage your application deployments. You need to have your app source code, and the Kubernetes manifests that describe the deployment, service, and ingress in the same Git repository.

Use the following command to perform port-forwarding to access the Argo instance locally:

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

Now fetch the Argo password using the following command:

kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}" | base64 -d

Create a public Git repository to store the Kubernetes manifests from which Argo will create the applications. You can use any Git hosting service, such as GitHub or GitLab, to create the repository.

We must provide the manifest(s) defining resources that will make up our application, such as pods, services, ingress rules, etc. Commit the manifest to your Git repository and push it to the remote repository. For now, you can use this Git repository. It contains manifests for an Nginx Web Server.

CLI Method

Step 1: Install ArgoCD's command line tool

brew install argocd

Step 2: Log in to the Argo instance on Kubernetes

Command:

argocd login localhost:8080

Output:

WARNING: server certificate had error: x509: certificate signed by unknown authority. Proceed insecurely (y/n)? y
Username: admin
Password:
'admin:login' logged in successfully
Context 'localhost:8080' updated

Step 3: Create the application

Command:

argocd app create nginx --repo https://github.com/nischal-subedi/cicd-kubernetes --path ./ --dest-server https://kubernetes.default.svc --dest-namespace nginx

Output:

application 'nginx' created

Step 4: Sync the application

Command:

argocd app sync nginx

Output:

TIMESTAMP                  GROUP        KIND   NAMESPACE                  NAME    STATUS   HEALTH        HOOK  MESSAGE
2023-02-21T11:13:30+05:45            Service     default             nginx-svc    Synced  Healthy
2023-02-21T11:13:30+05:45   apps  Deployment     default                 nginx    Synced  Healthy
2023-02-21T11:13:31+05:45            Service     default             nginx-svc    Synced  Healthy              service/nginx-svc configured
2023-02-21T11:13:31+05:45   apps  Deployment     default                 nginx    Synced  Healthy              deployment.apps/nginx configured

Name:               argocd/nginx
Project:            default
Server:             https://kubernetes.default.svc
Namespace:          default
URL:                https://localhost:8080/applications/nginx
Repo:               https://github.com/nischal-subedi/cicd-kubernetes
Target:             HEAD
Path:               ./
SyncWindow:         Sync Allowed
Sync Policy:        <none>
Sync Status:        Unknown
Health Status:      Healthy

Operation:          Sync
Sync Revision:      f1ae436b1b5406105feea6fa22ba3fca098af646
Phase:              Succeeded
Start:              2023-02-21 11:13:30 +0545 +0545
Finished:           2023-02-21 11:13:31 +0545 +0545
Duration:           1s
Message:            successfully synced (all tasks run)

GROUP  KIND        NAMESPACE  NAME       STATUS   HEALTH   HOOK  MESSAGE
       Service     default    nginx-svc  Synced   Healthy        service/nginx-svc configured
apps   Deployment  default    nginx      Synced   Healthy        deployment.apps/nginx configured

Step 5: Check the status of the Argo app

Command:

argocd app get nginx

Output:

Name:               argocd/ngninx
Project:            default
Server:             https://kubernetes.default.svc
Namespace:          nginx
URL:                https://localhost:8080/applications/nginx
Repo:               https://github.com/nischal-subedi/cicd-kubernetes
Target:
Path:               ./
SyncWindow:         Sync Allowed
Sync Policy:        <none>
Sync Status:        Synced to  (f1ae436)
Health Status:      Healthy

GROUP  KIND        NAMESPACE  NAME       STATUS  HEALTH   HOOK  MESSAGE
       Service     nginx      nginx-svc  Synced  Healthy        service/nginx-svc created
apps   Deployment  nginx      nginx      Synced  Healthy        deployment.apps/nginx created

GUI Method

Step 1: Access the login page

Open your browser and go to http://localhost:8080 to access the ArgoCD UI. Enter the username as admin and use the extracted password to log in.

Step 2: Create the application

Now click on the create application button and follow the images below.

Step 3: Sync the application

Once done, click on the Sync button.

Step 4: Check the app status

As this is a straightforward application, the app should immediately reach Healthy Status.

If you click on the app, you should see the resources being consumed in the node by the application, resource hierarchy, etc.

This all can be toggled in the top navigation bar beside the Log Out button. You can refer to the image shown below.

How does ArgoCD work?

Once we provide a repository to ArgoCD, it will continuously listen for any changes to the repository branch specified in the Argo Application.

Once a change is detected in the Kubernetes manifest of that branch (like pushing commits or merging changes from a different branch to the selected branch), Argo will apply the changes specified in the new Kubernetes manifest into the cluster. This can either be an update operation (kubectl apply) or a create operation (kubectl create).

Best Practices

ArgoCD provides several best practices when performing CI/CD on a Kubernetes cluster. Some of the best practices include:

Using GitOps to manage the deployments

GitOps is a great way to manage deployments in a Kubernetes cluster. It provides an auditable trail of all changes made to the deployments, making it easy to roll back to a previous version if needed.

Using namespaces to isolate environments

Make use of namespaces such as development, testing, and production. This makes it easy to manage different versions of the app and ensures that the deployments are isolated from each other.

Using Git branch protection

Use Git branch protection to merge only approved changes into the production branch. This helps prevent accidental deployments of untested code.

Frequently Asked Questions

1. What is ArgoCD?

ArgoCD is an open-source GitOps tool that helps automate the deployment of applications in a Kubernetes cluster. It uses Git repositories to manage the deployments and ensures they are always in sync with the Git repository.

2. How does ArgoCD work?

ArgoCD works by using GitOps to manage the deployments. It uses a Git repository to store the source code, and the Kubernetes manifests that describe the deployments, services, and ingresses. When changes are made to the Git repository, ArgoCD automatically syncs the changes to the Kubernetes cluster.

3. Can ArgoCD be used with other CI/CD tools?

Yes, ArgoCD can be used with other CI/CD tools, such as Jenkins, TravisCI, and CircleCI. The CI/CD tool can be used to build and test the app, and ArgoCD can be used to deploy the app to the Kubernetes cluster.

Conclusion

In this article, we learned about ArgoCD, its best practices, use cases and how it can be used to automate the deployment of an application in Kubernetes. In another article, we will learn to set up a complete CI/CD pipeline using ArgoCD.

Please comment below if you have any queries, and stay tuned for more on Kubernetes native CI/CD tools.