argocd-spoc-hub-model

This repository demonstrates the implementation of a multi-cluster GitOps deployment model using ArgoCD with a centralized Single Point of Contact (SPOC) hub architecture. The architecture involves a hub cluster and two SPOC clusters, all hosted on AWS EKS. This setup enables centralized management of ArgoCD applications across multiple Kubernetes clusters, ensuring streamlined operations, scalability, and visibility.

Architecture Overview

1. Hub Cluster (ArgoCD SPOC Hub)

   • The hub cluster acts as the centralized control plane.
   • It runs the ArgoCD instance, responsible for managing application deployments and synchronizing changes to the SPOC clusters.
   • The hub cluster is the entry point for all administrative tasks, such as managing applications, defining policies, and viewing logs.

2. SPOC Clusters (Single Point of Contact)

   • The SPOC clusters are dedicated Kubernetes clusters that receive the configurations and applications managed by the hub cluster.
   • These clusters contain the workloads and services deployed from the hub, with ArgoCD maintaining synchronization between the hub and SPOC clusters.
   • The SPOC clusters can be multi-region and multi-availability zone (AZ) to ensure high availability and fault tolerance.

Step 1: Create EKS Clusters

To set up the hub cluster and SPOC clusters, use the following eksctl commands.

eksctl create cluster -f /Users/akshaysiv/Workspace/github_projects/argocd-spoc-hub-model/eks/hub_cluster.yaml
eksctl create cluster -f /Users/akshaysiv/Workspace/github_projects/argocd-spoc-hub-model/eks/spoc_cluster1.yaml
eksctl create cluster -f /Users/akshaysiv/Workspace/github_projects/argocd-spoc-hub-model/eks/spoc_cluster2.yaml

These commands will create the following clusters:

• Hub Cluster: Defined in hub_cluster.yaml.
• SPOC Cluster 1: Defined in spoc_cluster1.yaml.
• SPOC Cluster 2: Defined in spoc_cluster2.yaml.

Make sure to verify the cluster creation process and confirm that all clusters are active before proceeding to the next steps.

Install ArgoCD in the Hub Cluster

To install ArgoCD in the hub cluster, follow these steps:

1. Add the ArgoCD namespace:

   kubectl create namespace argocd

2. Install ArgoCD using the official manifests:

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

3. Verify the installation: Ensure all ArgoCD components are running:

   kubectl get pods -n argocd

4. Access the ArgoCD UI:

   • Expose the ArgoCD server using a LoadBalancer or port-forwarding:

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

   • Access the UI at https://localhost:8080.

5. Retrieve the admin password:

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

6. Login to ArgoCD: Use the username admin and the retrieved password to log in.

Once ArgoCD is installed and accessible, you can proceed to configure it for managing applications across the SPOC clusters.

Add SPOC Clusters to the Hub Cluster

To manage the SPOC clusters from the hub cluster using ArgoCD, follow these steps:

1. Install kubectl and argocd CLI tools: Ensure you have the required CLI tools installed on your local machine:

   brew install argocd

2. Add the SPOC clusters to the hub cluster: Use the following commands to add the SPOC clusters to the ArgoCD instance running in the hub cluster.

   # Login to ArgoCD
   argocd login <ARGOCD_SERVER> --username admin --password <ADMIN_PASSWORD> --insecure
   
   # Add SPOC Cluster 1
   argocd cluster add spoc-cluster1-context
   
   # Add SPOC Cluster 2
   argocd cluster add spoc-cluster2-context

   Replace <ARGOCD_SERVER> with the ArgoCD server URL (e.g., localhost:8080 if port-forwarding is used) and <ADMIN_PASSWORD> with the admin password retrieved earlier. Replace spoc-cluster1-context and spoc-cluster2-context with the respective kubeconfig contexts for the SPOC clusters.

   

3. Verify the clusters are added: Run the following command to list the clusters managed by ArgoCD:

   argocd cluster list

   You should see the hub cluster and both SPOC clusters listed.

   

Once the SPOC clusters are added, you can start deploying applications from the hub cluster to the SPOC clusters using ArgoCD.

Deploy Applications Using ApplicationSet

Instead of manually creating applications in the ArgoCD UI, you can use an ApplicationSet to automate the deployment of applications across multiple clusters. The ApplicationSet controller allows you to define a single configuration that dynamically generates ArgoCD applications for all target clusters.

Here’s an example of an ApplicationSet configuration to deploy a sample application (e.g., guestbook) to all clusters:

1. Install the ApplicationSet Controller: Ensure the ApplicationSet controller is installed in your ArgoCD instance:

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

2. Create an ApplicationSet Manifest: Save the following YAML configuration as applicationset.yaml:

   apiVersion: argoproj.io/v1alpha1
   kind: ApplicationSet
   metadata:
     name: guestbook-applicationset
     namespace: argocd
   spec:
     generators:
        - list:
             elements:
                - cluster: spoc-cluster1
                   url: https://<SPOC_CLUSTER1_API_SERVER>
                - cluster: spoc-cluster2
                   url: https://<SPOC_CLUSTER2_API_SERVER>
     template:
        metadata:
           name: guestbook-{{cluster}}
        spec:
           project: default
           source:
             repoURL: https://github.com/argoproj/argocd-example-apps.git
             targetRevision: HEAD
             path: guestbook
           destination:
             server: "{{url}}"
             namespace: default

   Replace <SPOC_CLUSTER1_API_SERVER> and <SPOC_CLUSTER2_API_SERVER> with the API server URLs of the respective SPOC clusters.

3. Apply the ApplicationSet: Apply the manifest to create the ApplicationSet:

   kubectl apply -f applicationset.yaml

4. Verify the Applications: Check that the applications are created and synchronized for each cluster:

   argocd app list

   You should see applications like guestbook-spoc-cluster1 and guestbook-spoc-cluster2 listed.

Using ApplicationSet, you can easily manage deployments across multiple clusters without manually creating applications in the ArgoCD UI.