Running ArgoCD in Two Different Regions for Failover

Introduction to GitOps and ArgoCD

In the realm of modern DevOps practices, GitOps has emerged as a powerful paradigm for managing infrastructure and application deployments. GitOps leverages Git as the single source of truth for declarative infrastructure and applications, enabling teams to use Git workflows for deployment and operations. This approach ensures consistency, traceability, and improved collaboration among teams.

ArgoCD is a popular continuous delivery tool specifically designed for Kubernetes, which implements GitOps principles. It provides a declarative way to manage Kubernetes resources, automatically synchronizing the desired state defined in Git with the actual state in the cluster.

Why Run ArgoCD in Multiple Regions?

Running ArgoCD in multiple regions can significantly enhance the resilience and availability of your continuous delivery pipeline. Here are some reasons why you might want to consider this setup:

1. High Availability: Deploying ArgoCD in multiple regions ensures that if one region goes down, the other can continue managing deployments, minimizing downtime.
2. Disaster Recovery: Multi-region deployment provides a failover mechanism, allowing seamless recovery in case of regional outages or disasters.
3. Regulatory Compliance: Some regulations require data and applications to be deployed in specific geographic regions. Multi-region deployment helps meet these compliance requirements.

Challenges with Active/Active ArgoCD

ArgoCD does not natively support active/active configurations due to potential conflicts in the application controller. If two ArgoCD instances are running simultaneously and trying to synchronize changes, they can conflict with each other, causing deployment issues.

Proposed Solution

To overcome this challenge, we can configure both ArgoCD instances with identical settings but define staggered sync windows. This way, each instance performs synchronization in alternating intervals, avoiding conflicts while ensuring continuous deployment capabilities.

Step-by-Step Implementation

1. Deploy ArgoCD Instances

First, deploy two ArgoCD instances in different regions. Ensure both instances are configured with the same settings, repositories, and target clusters. For a detailed tutorial on deploying ArgoCD, you can refer to this guide.

2. Configure Sync Windows

Define sync windows for each ArgoCD instance. The idea is to have one instance perform synchronization during minute 0, 10, 20, 30, 40, and 50, while the other instance handles synchronization during minute 5, 15, 25, 35, 45, and 55. This configuration ensures that they do not overlap, preventing conflicts.

ArgoCD Instance 1 Sync Window Configuration:

apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
  name: example-project
spec:
  syncWindows:
    - kind: allow
      schedule: "0,10,20,30,40,50 * * * *"
      duration: "5m"

ArgoCD Instance 2 Sync Window Configuration:

apiVersion: argoproj.io/v1alpha1
kind: AppProject
metadata:
  name: example-project
spec:
  syncWindows:
    - kind: allow
      schedule: "5,15,25,35,45,55 * * * *"
      duration: "5m"

3. Verify Sync Window Configuration

After applying the sync window configurations, verify that each ArgoCD instance respects its designated sync window. You can check the synchronization logs to ensure they are performing updates at the correct times without overlapping.

4. Test Failover

Simulate a failover scenario by taking one ArgoCD instance offline. Observe how the other instance continues to perform synchronizations without any issues. Once the offline instance is back online, ensure that it resumes its synchronization activities as expected.

Conclusion

By configuring staggered sync windows, we can successfully run ArgoCD in an active/active configuration across multiple regions. This setup ensures high availability and failover capabilities without conflicts in the application controller. With this approach, you can leverage ArgoCD's powerful continuous deployment features while maintaining a robust and resilient infrastructure.

Implementing this strategy allows your organization to achieve seamless failover and maintain continuous delivery even in the face of regional outages. If you have any questions or need further assistance, feel free to leave a comment below.