How to create applications in ArgoCD

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This blog will show different ways of creating applications in ArgoCD, So Stay Tuned!

PREREQUISITES

• Kubernetes Cluster up and running on Local, minikube, or any Cloud providers
• GitHub or Gitlab Account

First, let us understand few concepts of ArgoCD

ArgoCD is a GitOps continuous delivery tool that means you define all your applications, manifests, and resources that you want to deploy in your Kubernetes cluster, you define all of them in your GitHub repository, and then the ArgoCD will pull the changes from your GitHub repository and deploy resources for you in your Kubernetes cluster.

It supports:-

• Kubernetes YAML files
• Helm Charts
• Kustomize files
• Template files that generate Kubernetes manifest.

Continuous Delivery workflow with ArgoCD

• Firstly, deploy ArgoCD in Kubernetes Cluster.
• Secondly, configure ArgoCD and tell it to connect to the particular GitHub repository.
• Thirdly, if something changes in the repository, it will automatically pull those changes and apply them in the cluster.

Best practice for GitHub repository

• Firstly, have a separate Git repository for application source code and application configuration.
• Secondly, a separate repository for system configuration.

As soon as the configuration file changes, ArgoCD in the cluster will immediately know about it because we configured it at the beginning to constantly monitor the changes and it will pull and apply changes in the cluster automatically.

How to create applications(Using User-Interface)

1. Set up ArgoCD on Kubernetes Cluster

(a) Firstly, create namespace

kubectl create namespace argocd

(b) Secondly, apply the YAML file(that installs all the necessary things)

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

(c) Thirdly, check pods

kubectl get pods -n argocd

2. Access Argocd UI

(a) Check services in argocd namespace

kubectl get service -n argocd

In my case the service type is LoadBalancer.

(b) Now, access the ArgoCD UI(in LoadBalancer simply copy the External-ip)

(c) Login into the ArgoCD server

The password for admin is stored in secret with the name- argocd-initial-admin-secret and also decodes the password.

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

echo ZVF1ZHVZU21OR1RqTFViWg== | base64 --decode

Now, Sign In

Let’s start creating applications

Firstly, through UI

Click on +NEW APP and fill in the details like:-

• application name- demo
• project- default
• sync policy- manual
• repository URL- where your application is present
• path- in which the YAML files are located
• cluster URL- select the cluster URL you are using
• namespace- default

Leave the rest of the spaces empty for the time being

Moreover, for this outofsync status, we have to enable the auto-sync policy which is present inside the APP DETAILS by clicking on this demo application.

So, this is the first way of creating the application through UI.

Let’s, create the application using CLI

For the CLI, first, we have to install the argocd binary

wget https://github.com/argoproj/argo-cd/releases/download/v2.4.2/argocd-linux-amd64

Change the name of the binary(optional)

mv argocd-linux-amd64 argocd

Change permissions

chmod +x argocd

Move this file to another directory

sudo mv argocd /usr/local/bin

Now, type argocd help to check the available commands

Login to the server using your cluster IP and the port, in my case the service is LoadBalancer so I am using the External-IP

argocd login [external-ip]

Now, let’s create the application. Therefore, I am using the same example that I have used in the UI demo but with the different application name

argocd app create [app-name] --project [name] --repo [git repo URL] --path [app folder] --dest-namespace [namespace] --dest-server [server URL]

argocd app create demo1 --project default --repo https://github.com/Jasmine-Harit/gitops-certification-examples.git --path ./simple-app --dest-namespace default --dest-server https://kubernetes.default.svc

KEY POINTS:-

• app-name- is the name you want to give your app(like demo1)
• project- is the name of the project created or default
• app folder- the path to the configuration for the application in the repository
• git repo- it is the URL of the git repository where the configuration file is located
• dest-namespace- the name of the target namespace in the cluster where the application is deployed
• server URL- use https://kubernetes.default.svc to reference the same cluster where ArgoCD has been deployed

Now, let’s check the list of apps and the information of a particular app

argocd app list

argocd app get [app-name]

argocd app get demo1

Another way to create applications is by writing a YAML file

I am going to use the Gitlab example for this demo.

(a) Clone the repository and Create a YAML file

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

Points to remember:- Inside automated, there are two things selfHeal is used for when you make changes directly to the cluster so argocd will automatically detect it and prune is used for when you remove or delete files from your repository that also argo will detect.

Now, apply this YAML using

kubectl apply -f [yaml file name]

kubectl apply -f application.yaml

CONCLUSION:-

Hence, these are the few different ways through which you can create your Argo applications and manage them easily.

HAPPY LEARNING!

REFERENCES:-

ArgoCD- Click

Demo- Click