ArgoCD Concepts Terminology

Before exploring Argo CD’s architecture, it’s essential to understand the core concepts and terminology that power its GitOps workflows.

Note

You should already be familiar with GitOps Principles, [Git], [Docker], [Kubernetes], and CI/CD basics to get the most out of Argo CD.

Application

An Application is a Kubernetes Custom Resource Definition (CRD) that represents a deployable unit in Argo CD. When you install Argo CD, the Application CRD is automatically registered in your cluster.

Application Source Types

Argo CD uses source types to render Kubernetes manifests before applying them to your cluster. Supported source types include:

Source Type	Description	Examples
Helm	Package manager for Kubernetes	Official charts from [Helm]
Kustomize	Declarative overlays	`kustomization.yaml`
YAML	Plain manifests	Any `.yaml` or `.yml` file
Plugin	Custom rendering tools	[Jsonnet], Kapitan, and community-built plugins

Project

An Argo CD Project provides namespace and repository isolation. Projects enable multi-tenancy by restricting which Git repositories, clusters, and namespaces grouped Applications can access.

Target State

Also called the desired state, the Target State is the set of Kubernetes manifests stored in a Git repository (or other supported source). This defines how your environment should look at any point in time.

Live State

The Live State represents the actual, running state of your Kubernetes resources (Pods, Services, ConfigMaps, Secrets, etc.) in your cluster.

Synchronization (Sync)

A Sync is the process of reconciling the Live State with the Target State. When you create or update an Argo CD Application, Argo CD applies the changes from Git to your cluster.

Sync Status

Sync Status indicates whether your cluster matches the desired manifests:

Synced: Cluster state matches the Git repository.
OutOfSync: Differences exist between the cluster and the repository.

Operation Status

Operation Status reflects the result of the last sync operation:

Succeeded: Sync completed without errors.
Failed: Sync encountered one or more errors.

Refresh

A Refresh re-evaluates the Live State against the Target State:

If auto-sync is enabled, detected differences will trigger an automatic sync.
Otherwise, administrators receive a notification to initiate a manual sync.

Warning

Enabling auto-sync can lead to unexpected rollbacks if manual changes are made directly to the cluster.

Health Assessment

Argo CD performs built-in health checks for standard Kubernetes resources and reports overall status categories:

Healthy
Degraded
Progressing
Missing

The image is a chart explaining ArgoCD concepts and terminology, including definitions for terms like "Application," "Target state," "Sync status," and "Health," with related icons.

Note

If you can’t view the chart, review the definitions above for a complete overview of Argo CD concepts and terminology.

By mastering these terms, you’ll navigate the Argo CD [dashboard], CLI, and API with confidence and manage your GitOps pipelines more effectively.

References

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