Let’s get started.<\/p>\n
Argo CD Architecture Overview<\/h2>\n
Argo CD has the following seven key components.<\/p>\n
- \n
- Argocd Server (API Server)<\/li>\n
- Application Controller<\/li>\n
- ApplicationSet Controller<\/li>\n
- Repository Server<\/li>\n
- Dex (optional SSO)<\/li>\n
- Redis<\/li>\n
- Notification Controller<\/li>\n<\/ol>\n
The following diagram shows you the overall architecture of Argocd.<\/p>\n
![\"argocd](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/03\/image--1-.webp\")
<\/figure>\nThe diagram shown only three components of Argo CD, but there are also other components that work with these components.<\/p>\n
In the next section, we will look into each component in detail.<\/p>\n
Component Deep Dive<\/h2>\n
Now lets look at each component in detail.<\/p>\n
\n\ud83d\udca1<\/div>\nThe components are deployed as a deployment except the Application Controller, it is deployed as a StateFulSet (An important distinction we will come back to when discussing scaling).<\/div>\n<\/div>\nArgo CD Server<\/h3>\n
This is the API server of Argo CD that exposes Argo CD REST APIs, which we use to interact with Argo CD<\/a> through UI, CLI, and CI\/CD tools.<\/p>\n
![\"Argo](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/01\/architecture6.2.png\")
<\/figure>\nBy default, the Argo CD server saves and manages the user credentials in a Kubernetes secret<\/strong>, the user account configuration and permissions in a Kubernetes configmap.<\/p>\n
Also, this is the component that saves the data of custom resources like Application, ApplicationSet, and Projects in ETCD<\/strong>. This is important for backup and recovery, which we will cover later.<\/p>\n
Argo CD Application Controller<\/h3>\n
Application Controller is the core component of Argo CD<\/a> and a Kubernetes controller, which deploys and manages the application.<\/p>\n
Its key roles are to deploy and continuously monitor the Applications created by it and compare their live state with the desired state in Git<\/a>.<\/p>\n
\n\ud83d\udca1<\/div>\nEvery deployment done by Argo CD is referred to as an Application, it can be a tool, an application, or any deployment.<\/div>\n<\/div>\nGiven below is a simple image that shows how Argo CD Application Controller reads and creates applications.<\/p>\n
![\"Argo](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/01\/architecture5.2.png\")
<\/figure>\nArgo CD ApplicationSet Controller<\/h3>\n
ApplicationSet Controller is a Controller to manage ApplicationSet custom resource that helps you to deploy multiple applications using a single custom resource.<\/p>\n
When an ApplicationSet custom resource is created, the ApplicationSet Controller service reads it and creates multiple Application custom resources.<\/p>\n
Then the Application Controller reads the custom resources to deploy applications.<\/p>\n
This is helpful in deploying the same application to multiple environments and deploying all services of an application using a single custom resource.<\/p>\n
![\"Argo](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/01\/architecture4.2.png\")
<\/figure>\nArgo CD Repo Server<\/h3>\n
The repo server is the service that interacts with Git repositories and pulls the templates from the Git repository for the application deployment.<\/p>\n
![\"Argo](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/03\/07.png\")
<\/figure>\nWhen the Application Controller requests a manifest to create an application, the Repo server clones it locally and saves the cache in Redis for 24 hours.<\/strong><\/p>\n
The Repo server polls Git every 3 minutes by default to check for new changes, and you can also configure a webhook for Git.<\/p>\n
\n\ud83d\udca1<\/div>\nIf webhook is configured, Git sends webhook POST request to notify a new change is made.<\/div>\n<\/div>\nThe templates from Git can be in formats like,<\/p>\n
- \n
- Plain manifest files, <\/li>\n
- Helm charts<\/a>, and <\/li>\n
- Kustomize<\/a>.<\/li>\n<\/ul>\n
Argo CD Dex Server<\/h3>\n
Dex server is an OIDC<\/a> (OpenID Connect) provider for Argo CD, which helps to authenticate and authorize with external identity providers.<\/p>\n
It supports a wide range of OIDC providers like,<\/p>\n
- \n
- AWS SSO<\/li>\n
- Okta<\/li>\n
- Google<\/li>\n
- Microsoft (Azure AD)<\/li>\n
- GitHub, etc.<\/li>\n<\/ul>\n
In enterprise environments<\/strong>, you usually have a centralized identity manager. If it’s a supported OIDC provider, you can configure it to Argo CD, and you can allow people in a certain group to access Argo CD.<\/p>\n
In Argo CD, not allowing everyone to do anything is a best practice. You can use OIDC combined with RBAC <\/strong>to limit their permissions. <\/p>\n
For example, <\/p>\n
- \n
- DevOps engineers can create, delete, and sync applications <\/li>\n
- Developers can only access the UI to view the application and its logs.<\/li>\n<\/ul>\n
![\"Argo](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/01\/architecture8.3.png\")
<\/figure>\nRedis<\/h3>\n
Redis is used in Argo CD for caching, which makes the request fast and reduces the stress on other components by caching repeated API calls.<\/p>\n
As we see in the Repo server, the manifest cloned by the repo server during application deployment will be cached for 24 hrs.<\/strong> And it also caches the information of the resource Argo CD creates, caches the application state like its status, sync state.<\/p>\n
It does not store any credentials<\/strong> or configuration temporarily, they are stored in Kubernetes secrets and configmap.<\/p>\n
With Redis, there will be low resource usage, syncing applications get faster, and frequent requests to Git will be reduced if the cache is present.<\/p>\n
![\"Redis](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/01\/architecture9.2.png\")
<\/figure>\nArgo CD Notification Controller<\/h3>\n
The Notification Controller monitors the Application custom resource for new events (changes) and sends them as notifications<\/strong>, such as emails and Slack messages.<\/p>\n
![\"Argo](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2026\/01\/architecture10.3.png\")
<\/figure>\nArgo CD events such as changes in sync status, health status, when a new version is deployed, etc., can be configured to send notifications. And, you can use custom messages or templates to send in the notifications.<\/p>\n
Argo CD supports a wide range of notification services like ,<\/p>\n
- \n
- AWS SQS, <\/li>\n
- Slack, <\/li>\n
- Email, <\/li>\n
- Microsoft Teams<\/li>\n
- PagerDuty <\/li>\n
- And more..<\/li>\n<\/ul>\n
Now that you have an understanding of each component, let’s see how Argo CD saves its data.<\/p>\n
Argo CD Storage and Backup<\/h2>\n
Unlike other tools, Argo CD does not store its data in PV for persistence.<\/p>\n
It has a Redis database, but it is only for caching. The actual configuration data is stored as native Kubernetes objects<\/a>.<\/p>\n
![\"argocd](\"https:\/\/storage.ghost.io\/c\/5f\/2f\/5f2f4d20-2abf-4534-8d40-7aa233aedd43\/content\/images\/2025\/11\/1756465118036.jpeg\")
<\/figure>\nThe CRDs of Argo CD store data related to applications and projects.<\/p>\n
The configmaps in the argocd namespace contain general server configurations such as UI settings, RBAC<\/a>, etc.<\/p>\n
The secrets in the argocd namespace store all credentials, such as account username and password, cluster credentials, and all other authentication credentials.<\/p>\n
You can change the configurations on the configmap to make the changes, or when you change settings by CLI or UI, Argo CD will update the related configmap automatically.<\/p>\n
If you lose this data, recreating the configs manually can be time consuming.<\/p>\n
To perform a backup, you just need to back up the Argo CD namespace and the related CRDs.<\/p>\n
There are two main backup options:<\/p>\n
- Kustomize<\/a>.<\/li>\n<\/ul>\n