GitOps: Flux vs Argo CD

GitOps is a software development and operations methodology that uses Git as the source of truth for deployment configurations. It involves keeping the desired state of an application or infrastructure in a Git repository and using Git-based workflows to manage and deploy changes. Two popular open-source tools that help organizations implement GitOps for managing their Kubernetes applications are Flux and Argo CD. In this article, we’ll take a closer look at these tools, their pros and cons, and how to set them up. Read DZone’s related tutorial on how to automate CI/CD pipelines with Jenkins and Kubernetes.

Common Use Cases for Flux and Argo CD

Flux

• Continuous delivery: Flux can be used to automate the deployment pipeline and ensure that changes are automatically deployed as soon as they are pushed to the Git repository.
• Configuration management: Flux allows you to store and manage your application’s configuration as code, making it easier to version control and track changes.
• Immutable infrastructure: Flux helps enforce an immutable infrastructure approach—where changes are made only through the Git repository and not through manual intervention on the cluster.
• Blue-green deployments: Flux supports blue-green deployments where a new version of an application is deployed alongside the existing version, and traffic is gradually shifted to the new version.

Argo CD

• Continuous deployment: Argo CD can be used to automate the deployment process, ensuring that applications are always up-to-date with the latest changes from the Git repository.
• Application promotion: Argo CD supports application promotion—where applications can be promoted from one environment to another. For example, from development to production.
• Multi-cluster management: Argo CD can be used to manage applications across multiple clusters, ensuring the desired state of the applications is consistent across all clusters.
• Rollback management: Argo CD provides rollback capabilities, making it easier to revert changes in case of failures.

The choice between the two tools depends on the specific requirements of the organization and application, but both tools provide a GitOps approach to simplify the deployment process and reduce the risk of manual errors. They both have their own pros and cons, and in this article, we’ll take a look at what they are and how to set them up.

What Is Flux?

Flux is a GitOps tool that automates the deployment of applications on Kubernetes. It works by continuously monitoring the state of a Git repository and applying any changes to a cluster. Flux integrates with various Git providers such as GitHub, GitLab, and Bitbucket. When changes are made to the repository, Flux automatically detects them and updates the cluster accordingly. Related Tutorial: How to auto deploy spring boot apps using GitLab CI/CD.

Pros of Flux

• Automated deployments: Flux automates the deployment process, reducing manual errors and freeing up developers to focus on other tasks.
• Git-based workflow: Flux leverages Git as a source of truth, which makes it easier to track and revert changes.
• Declarative configuration: Flux uses Kubernetes manifests to define the desired state of a cluster, making it easier to manage and track changes.

Cons of Flux

• Limited customization: Flux only supports a limited set of customizations, which may not be suitable for all use cases.
• Steep learning curve: Flux has a steep learning curve for new users and requires a deep understanding of Kubernetes and Git.

How To Set Up Flux

Prerequisites

• A running Kubernetes cluster.
• Helm installed on your local machine.
• A Git repository for your application's source code and Kubernetes manifests.
• The repository URL and a SSH key for the Git repository.

Step 1: Add the Flux Helm Repository

The first step is to add the Flux Helm repository to your local machine. Run the following command to add the repository:

helm repo add fluxcd https://charts.fluxcd.io

Step 2: Install Flux

Now that the Flux Helm repository is added, you can install Flux on the cluster. Run the following command to install Flux:

helm upgrade -i flux fluxcd/flux \
--set git.url=git@github.com:<your-org>/<your-repo>.git \
--set git.path=<path-to-manifests> \
--set git.pollInterval=1m \
--set git.ssh.secretName=flux-git-ssh

In the above command, replace the placeholder values with your own Git repository information. The git.url parameter is the URL of the Git repository, the git.path parameter is the path to the directory containing the Kubernetes manifests, and the git.ssh.secretName parameter is the name of the SSH secret containing the SSH key for the repository.

Step 3: Verify the Installation

After running the above command, you can verify the installation by checking the status of the Flux pods. Run the following command to view the pods:

kubectl get pods -n <flux-namespace>

If the pods are running, Flux has been installed successfully.

Step 4: Connect Flux to Your Git Repository

The final step is to connect Flux to your Git repository. Run the following command to generate a SSH key and create a secret:

ssh-keygen -t rsa -b 4096 -f id_rsa
kubectl create secret generic flux-git-ssh \
--from-file=id_rsa=./id_rsa --namespace=<flux-namespace>

In the above command, replace the <flux-namespace> placeholder with the namespace where Flux is installed.

Now, add the generated public key as a deployment key in your Git repository.

You have successfully set up Flux using Helm. Whenever changes are made to the Git repository, Flux will detect them and update the cluster accordingly.

In conclusion, setting up Flux using Helm is a quite simple process. By using Git as a source of truth and continuously monitoring the state of the cluster, Flux helps simplify the deployment process and reduce the risk of manual errors.

What Is Argo CD?

Argo CD is an open-source GitOps tool that automates the deployment of applications on Kubernetes. It allows developers to declaratively manage their applications and keeps the desired state of the applications in sync with the live state. Argo CD integrates with Git repositories and continuously monitors them for changes. Whenever changes are detected, Argo CD applies them to the cluster, ensuring the application is always up-to-date. With Argo CD, organizations can automate their deployment process, reduce the risk of manual errors, and benefit from Git’s version control capabilities. Argo CD provides a graphical user interface and a command-line interface, making it easy to use and manage applications at scale.

Pros of Argo CD

• Advanced deployment features: Argo CD provides advanced deployment features, such as rolling updates and canary deployments, making it easier to manage complex deployments.
• User-friendly interface: Argo CD provides a user-friendly interface that makes it easier to manage deployments, especially for non-technical users.
• Customizable: Argo CD allows for greater customization, making it easier to fit the tool to specific use cases.

Cons of Argo CD

• Steep learning curve: Argo CD has a steep learning curve for new users and requires a deep understanding of Kubernetes and Git.
• Complexity: Argo CD has a more complex architecture than Flux, which can make it more difficult to manage and troubleshoot.

How To Set Up Argo CD

Argo CD can be installed on a Kubernetes cluster using Helm, a package manager for Kubernetes. In this section, we’ll go through the steps to set up Argo CD using Helm.

Prerequisites

• A running Kubernetes cluster.
• Helm installed on your local machine.
• A Git repository for your application’s source code and Kubernetes manifests.

Step 1: Add the Argo CD Helm Repository

The first step is to add the Argo CD Helm repository to your local machine. Run the following command to add the repository:

helm repo add argo https://argoproj.github.io/argo-cd

Step 2: Install Argo CD

Now that the Argo CD Helm repository is added, you can install Argo CD on the cluster. Run the following command to install Argo CD:

helm upgrade -i argocd argo/argo-cd --set server.route.enabled=true

Step 3: Verify the Installation

After running the above command, you can verify the installation by checking the status of the Argo CD pods. Run the following command to view the pods:

kubectl get pods -n argocd

If the pods are running, Argo CD has been installed successfully.

Step 4: Connect Argo CD to Your Git Repository

The final step is to connect Argo CD to your Git repository. Argo CD provides a graphical user interface that you can use to create applications and connect to your Git repository.

To access the Argo CD interface, run the following command to get the URL:

kubectl get routes -n argocd

Use the URL in a web browser to access the Argo CD interface.

Once you’re in the interface, you can create a new application by providing the Git repository URL and the path to the Kubernetes manifests. Argo CD will continuously monitor the repository for changes and apply them to the cluster.

You have now successfully set up Argo CD using Helm. 

Conclusion

Kubernetes and DevOps are a key part of the software development lifecycle, and GitOps is a valuable approach for automating the deployment and management of applications on Kubernetes. Flux and Argo CD are two popular GitOps tools that provide a simple and efficient way to automate the deployment process, enforce an immutable infrastructure, and manage applications in a consistent and predictable way.

Flux focuses on automating the deployment pipeline and providing configuration management as code, while Argo CD provides a more complete GitOps solution, including features such as multi-cluster management, application promotion, and rollback management. Both tools have their own strengths and weaknesses, and the choice between the two will depend on the specific requirements of the organization and the application.

Regardless of the tool chosen, GitOps provides a valuable approach for simplifying the deployment process and reducing the risk of manual errors. By keeping the desired state of the applications in sync with the Git repository, GitOps ensures that changes are made in a consistent and predictable way, resulting in a more reliable and efficient deployment process.