Understanding Argo CD

Argo CD is a declarative, GitOps continuous delivery tool that helps in managing and deploying applications to Kubernetes clusters. It automates the deployment process by ensuring that the state of the cluster matches the desired state defined in a Git repository.

This article will explain how to use Argo CD to deploy applications to Kubernetes.

Prerequisites:

Before getting started with Argo CD, you must have a basic understanding of Kubernetes and Git.

Step-by-Step Instructions:

1. Installing Argo CD:

Argo CD can be installed on Kubernetes using either a YAML manifest file or a Helm chart. The recommended way to install Argo CD is by using the Helm chart. To install Argo CD using Helm, run the following commands:

helm repo add argo https://argoproj.github.io/argo-helm
helm install argocd argo/argo-cd --version X.X.X --namespace argocd

Note: Replace X.X.X with the latest version number.

2. Accessing Argo CD UI:

After the installation is complete, you can access the Argo CD UI by running the following command:

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

This command will create a tunnel to the Argo CD server and expose it on port 8080. You can access the Argo CD UI by navigating to https://localhost:8080 in your web browser.

3. Adding an Application:

To add an application to Argo CD, you need to create a YAML manifest file that defines the desired state of the application. This manifest file should be stored in a Git repository that Argo CD can access.

Here's an example manifest file for a simple Kubernetes deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

To add this application to Argo CD, run the following command:

argocd app create nginx --repo <GIT_REPO_URL> --path <PATH_TO_MANIFEST_FILE> --dest-server https://kubernetes.default.svc --dest-namespace default

Replace <GIT_REPO_URL> with the URL of your Git repository and <PATH_TO_MANIFEST_FILE> with the path to your manifest file within the repository.

4. Deploying an Application:

To deploy an application using Argo CD, you need to sync the application with the desired state defined in the Git repository. You can do this by running the following command:

argocd app sync nginx

This command will compare the current state of the application in the cluster with the desired state defined in the Git repository and make any necessary changes to ensure that they match.

5. Monitoring Application:

Argo CD provides a comprehensive UI for monitoring the state of applications in the cluster. You can access the UI by navigating to https://localhost:8080/applications in your web browser.

Argo CD is an excellent tool for managing and deploying applications to Kubernetes clusters. It provides a simple and efficient way to automate the deployment process using GitOps principles. With this guide, you should be able to get started with Argo CD and deploy your applications to Kubernetes with ease.

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That's it for this post. Keep practicing and have fun. Leave your comments if any.