Note_Tech

All technological notes.

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ArgoCD - Architecture

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• ArgoCD - Architecture
  • Architecture
    • ArgoCD Server
    • Repo Server
    • Application controller
    • Additional Components

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Architecture

3 main components:

• ArgoCD Server (API + Web Server).
• ArgoCD Repo Server.
• ArgoCD Application Controller.

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ArgoCD Server

• Its a gRPC/REST server which exposes the API consumed by the Web UI, CLI.
  • Application management (Create, Update, Delete).
  • Application operations (ex: Sync, Rollback)
  • Repos and clusters management.
  • Authentication.

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Repo Server

• Repo Server
  • acts as the bridge between Git repositories and Kubernetes.
  • roles:
    • Clones and keeps Git repositories up-to-date.
    • generates Kubernetes manifests (via Helm, Kustomize, etc.),
    • and caches them

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Application controller

• Application controller
  • a Kubernetes controller which continuously monitors running applications and compares the current, live state against the desired target state.
• Roles:
  • Communicate with Repo server to get the generated manifests.
  • Communicate with k8s API to get actual cluster state.
  • Deploy apps manifests to destination clusters.
  • Detects OutofSync Apps and take corrective actions “If needed”.
  • Invoking user-defined hooks for lifecycle events (PreSync, Sync, PostSync).
• How it Works:
  • Observes:
    • It looks at the Argo CD Application CRD and the target cluster.
  • Compares:
    • It fetches the desired manifests from the repo server and compares them to the actual state.
  • Acts:
    • It updates the Application status and synchronizes the cluster if enabled.

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Additional Components

• Redis: used for caching.
• Dex: identity service to integrate with external identity providers.
• ApplicationSet Controller: It automates the generation of Argo CD Applications

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