Introduction to ArgoCD & Jenkins

Introduction to ArgoCD

ArgoCD is an open-source GitOps continuous delivery tool designed to automate the deployment and management of applications in Kubernetes clusters. It follows the GitOps philosophy, where the desired state of your applications and infrastructure is defined in Git repositories, and ArgoCD ensures that the actual state matches the desired state.

Advantages of ArgoCD

GitOps Approach: ArgoCD embraces the GitOps approach, which improves transparency, repeatability, and collaboration by using Git repositories as the source of truth for infrastructure and application configurations.
Automated Deployments: ArgoCD automatically syncs the desired state in your Git repository with the actual state in the Kubernetes cluster, ensuring that your applications are always up-to-date and in the desired configuration.
Rollbacks and Auditing: ArgoCD allows you to easily roll back to previous application versions if needed. It provides a clear audit trail of changes and deployments.
Multi-Cluster and Multi-Environment Support: ArgoCD can manage deployments across multiple Kubernetes clusters and environments, making it suitable for complex scenarios.
Declarative Configuration: Define your application's configuration declaratively using Git repositories, YAML files, and Kubernetes manifests.

CD workflow without ArgoCD

So whenever the application is pushed to the git repository, there are certain steps it goes through to reach the deployment. These steps are automated and known as CI/CD pipeline. So once the code changes are pushed they are tested, the image is built, pushed to the DockerHub or other registry, Manifest files are updated, and finally through Kubectl apply... it is applied to the Kubernetes cluster.

But in this case, we have to face and resolve challenges like:

Install and setup tools like kubectl
Configuring access to Kubernetes
Configuring access to could providers
Several security challenges
No visibility of deployment status

Source: Tech with Nana youtube video

CD workflow with ArgoCD

So in a general scenario, the above-mentioned workflow is used, but while working with Kubernetes we might need to change this workflow. It is essential to know that according to the set best practice for the Git repository, we should have two separate repositories for Code files and application configuration (k8s manifests).

The main advantage is there can be a time we want to change only the config files but don't want the test -> to build an etc workflow to run as the configs can be changed independently of the application built. Having this as a reference now ArgoCD (which is installed on your Kubernetes Cluster) keeps track of the state you mentioned in the configuration repositories.

So if were to use the earlier CI/CD pipeline then it would have been too complex to manage and configure. Once the application is built and up the changes are reflected in the configuration files. These changes are detected by ArgoCD and pulled into the cluster.

Note: ArgoCD works on the pull method and not like the usual push method

Introduction to Jenkins

Jenkins is an open-source automation server that facilitates building, testing, and deploying software. It provides a platform for creating and orchestrating CI/CD pipelines, which automate the process of integrating code changes, running tests, and deploying applications.

Advantages of Jenkins

Extensibility: Jenkins has a vast ecosystem of plugins that allow you to integrate with various tools, version control systems, testing frameworks, and deployment platforms.
Continuous Integration: Jenkins enables continuous integration by automatically building and testing code changes as they are pushed to the repository, providing early feedback to developers.
Pipeline as Code: Jenkins supports defining pipelines as code using the Jenkinsfile, which allows version control, code reviews, and reproducibility of the entire build and deployment process.
Wide Range of Integrations: Jenkins integrates with popular version control systems like Git, various testing frameworks, and deployment platforms like Kubernetes, AWS, and more.

Setting Up ArgoCD

Install ArgoCD on your Kubernetes cluster:

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

Access ArgoCD's web UI:

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

Define an application using a Git repository:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: sample-app
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/your/repo.git
    path: path/to/app
  destination:
    server: 'https://kubernetes.default.svc'
    namespace: default

Setting Up Jenkins

Install Jenkins on your server or container:

docker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts

Access Jenkins through a web browser and complete the setup wizard.
Install the recommended plugins and any additional plugins you need.
Create a Jenkinsfile in your repository for defining a pipeline:

pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                sh 'echo "Building..."'
            }
        }
        stage('Test') {
            steps {
                sh 'echo "Testing..."'
            }
        }
        stage('Deploy') {
            steps {
                sh 'echo "Deploying..."'
            }
        }
    }
}

Create a new pipeline job in Jenkins, point it to your repository, and configure the pipeline script from the Jenkins file.

Remember that both ArgoCD and Jenkins require more configuration and customization based on your environment and use cases. These steps are simplified for demonstration purposes. Always refer to the official documentation and resources for detailed setup and best practices.

Resources

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What is ArgoCD & Jenkins , Introduction, Advantages & Demo with Codes

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