Argo CD — Fundamentals

Argo CD is an open-source, GitOps continuous delivery tool for Kubernetes applications. It uses Git as a source of truth, and updates applications based on current Kubernetes manifests or Helm charts. This allows it to manage applications, configurations, and environments in one system, in a way that is declarative, and version controlled.

Purpose:

Argo CD helps prevent configuration drift and maintain state traceability by using Git as a single source of truth for all current and past deployments. The Git history enables retrospective investigation. Argo CD is used to automate the deployment and management of Kubernetes applications.

Uses:

1. Deploy new applications to Kubernetes clusters.
2. Update existing applications in Kubernetes clusters.
3. Roll back applications to previous versions.
4. Manage application configurations.
5. Monitor application health.

Argo CD is a powerful tool that can help you to automate your Kubernetes deployments and improve the reliability of your applications.

Here is a diagram of how Argo CD works:

Git Repository

├── Kubernetes manifests

└── Helm charts

Argo CD

├── API Server

└── Agents

└── Kubernetes clusters

The Argo CD API Server is responsible for managing applications and their status. It communicates with the agents, which are deployed to each Kubernetes cluster that Argo CD manages. The agents are responsible for reconciling applications to their desired state.

The desired state of an application is defined in the Git repository. The Argo CD API Server uses the repository to track the state of applications and to trigger reconciliation when changes are made to the repository.

Argo CD can be used to deploy applications to any Kubernetes cluster. It is a powerful tool that can help you to automate your Kubernetes deployments and improve the reliability of your applications.

Here are some of the benefits of using Argo CD:

• Declarative: Argo CD uses Git as a source of truth, so you can define the desired state of your applications in a declarative way. This makes it easy to track changes and roll back to previous versions.
• Version controlled: Argo CD tracks the state of your applications in Git, so you can always go back to a previous version if something goes wrong.
• Reusable: Argo CD applications can be reused across different Kubernetes clusters. This makes it easy to deploy the same application to multiple environments.
• Scalable: Argo CD is designed to scale to large numbers of applications.

If you are looking for a way to automate your Kubernetes deployments and improve the reliability of your applications, then Argo CD is a great option. It is a powerful tool that can help you to achieve your goals.

ArgoCD Lifecycle hooks:

1. Presync
2. Sync
3. PostSync

ArgoCD Components

1. API Server — make the user contact with the Argo CD Server
2. Repo Server — Clone the code from git, generate manifests k8s for deployment
3. Application Controller — Communicate with APPI server (cluster state) and repo server (k8s manifests), deploy and monitor the cluster
4. Redis — caching
5. Dex — identity service to connect with external service providers
6. ApplicationSetController — Automates the generation of ArgoCD Applications