ArgoCD Introduction

Argo CD is a popular GitOps controller. It is used to deploy applications to Kubernetes clusters. It is also used to manage the configuration of the cluster itself. It can be changed too.

"One the founding principles of GitOps - everything stored in Git."

• For production we can use the Autopilot. For a traditional approach we can use the Manifest directory approach. Community Helm charts are also available

Installation

• By applying the manifests . Reference: ArgoCD Installation

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

Default credentials:

• Username: admin
• Password : It can be found by running the following command

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

Sync Policy - Features

• Auto Sync - ArgoCD will automatically sync the application with the Git repository. This is done by polling the Git repository at a specified interval.

• Self Healing - If the changes are done directly to deployment/cluster, it will discard those changes and keep the state as per the Git repository. For example, if someone change the replica count to two from 1 from the CLI, it will be changed back to 1.

• Auto Pruning - ArgoCD will automatically delete the resources that are not present in the Git repository. By default, it will not.

Progressive Delivery

Progressive Delivery is the practice of deploying an application in a gradual manner allowing for minimum downtime and easy rollbacks. There are several forms of progressive delivery such as blue/green, canary, a/b and feature flags.

• Blue/Green - Deploy the new version of the application to a new environment and then switch the traffic to the new environment. This is the most common form of progressive delivery. It is also the most complex to implement. It requires a lot of infrastructure and a lot of testing.

• Canary - Deploy the new version of the application to a small subset of users. If the new version is working fine, then deploy it to the rest of the users. This is the most common form of progressive delivery. It is also the most complex to implement. It requires a lot of infrastructure and a lot of testing.

• To make the whole setup declarative way and make it infrastructure as we deploy ArgoCD Argo CD applications just like any other Kubernetes resource. This is also managed through a git repository.

Docs for reference.

Sample YAML:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: nginx-app # This is the name of the application
  namespace: argocd 
spec:
    destination:
        namespace: argocd # This is the namespace where the application will be deployed
        server: https://kubernetes.default.svc # This is the default server
    project: default
    source:
        path: ./manifest # This is the path where the manifest is present
        repoURL: https://github.com/sarafpradumna/argo-test # This is the repo where the manifest is present
        targetRevision: HEAD
    syncPolicy:
        automated:
            prune: true
            selfHeal: true
            allowEmpty: false #By default it is false
        syncOptions:
        - CreateNamespace=true # This will create namespace if not present

What's next?

• Learning Resources - Learn more about ArgoCD with these resources.
• Other Resources - Explore more about ArgoCD with these resources.