Your first Application | DevOps Peach

An Application is a CRD that says which repo, path and revision to deploy, to which cluster and namespace, inside which project.

An Application connects one source in Git to one destination in a cluster:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: shop-api-dev
  namespace: argocd                     # Applications live in the Argo CD namespace
spec:
  project: default                      # AppProject: guard rails (module 3)
  source:
    repoURL: https://github.com/example-org/shop-config.git
    targetRevision: main                # branch, tag or commit SHA
    path: apps/shop-api/overlays/dev    # folder inside the repo
  destination:
    server: https://kubernetes.default.svc   # the cluster Argo CD runs in
    namespace: shop-dev
  syncPolicy:
    syncOptions: [CreateNamespace=true]

Field	Meaning
`source.repoURL`	Git (HTTPS or SSH), a Helm repository or an OCI registry
`targetRevision`	What to track. A branch follows new commits; a tag or SHA is fixed
`source.path`	Folder with YAML, a Kustomize overlay or a Helm chart; Argo CD detects the type
`destination.server` / `name`	Target cluster by API URL or by registered name
`destination.namespace`	Default namespace for objects that do not set one
`project`	The AppProject that limits repos, clusters and resource kinds

Three ways to create it

# 1. CLI
argocd app create shop-api-dev \
  --repo https://github.com/example-org/shop-config.git \
  --path apps/shop-api/overlays/dev --revision main \
  --dest-server https://kubernetes.default.svc --dest-namespace shop-dev \
  --sync-option CreateNamespace=true

# 2. Declaratively – the GitOps way
kubectl apply -n argocd -f shop-api-dev.yaml

# 3. Web UI: + NEW APP

The declarative way is preferred: the Application YAML itself goes into Git (the "app of apps" pattern in module 3 manages these files for you).

Sync it

A new Application starts OutOfSync and Missing: Git has objects the cluster does not. Without an automated policy nothing happens until you sync:

argocd app sync shop-api-dev
argocd app wait shop-api-dev --health --timeout 120
argocd app get shop-api-dev

argocd app get lists every resource with its own sync and health status, plus the revision (commit SHA) that was applied — the link between the cluster and a line in the Git history.

Delete carefully

argocd app delete shop-api-dev            # cascade: also deletes the Deployment, Service ...
argocd app delete shop-api-dev --cascade=false   # keep the workloads, remove only the Application

With kubectl delete application, cascading only happens if the Application carries the finalizer resources-finalizer.argocd.argoproj.io. Without it, the workloads stay running but become unmanaged.

Tip: name Applications <app>-<env> and use labels (team=shop, env=dev) so argocd app list -l env=prod works.