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ArgoCD - Application

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• ArgoCD - Application
  • Application
    • Application CRD vs Kubernetes Manifests
    • Supported Tools
  • Common Commands
  • Lab: Create Application
    • Method: Ddeclarative
    • Method: CLI
    • Method: UI
  • Tools: Helm
    • Common Options
    • Lab: Create App with Helm
  • Tools: Directory manifests
  • Tools: Kustomize
    • Lab: Create App with Kustomize
  • Tools: Multiple Sources
  • Tracking Strategies

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Application

• Application
  • a Kubernetes Custom Resource Definition (CRD) that defines the desired state of an application in a target cluster, sourcing its configuration (YAML, Helm, Kustomize) from a Git repository.
  • the unit of deployment and tracking, enabling GitOps by monitoring for differences between the Git repository and the cluster.
• key spec entries:
  • spec.project:
    • Specify under which Argo CD project should the application be managed.
    • default project: default
  • spec.source
    • specify WHERE is the desired state defined
    • includes a Git repository URL, a branch, and a path or Helm chart.
  • spec.destination
    • Specify WHERE should the manifests from that source be deployed.
    • which cluster and namespace
  • spec.syncPolicy:
    • Specify HOW should the deployment be managed
    • Should it be automated, prune resources, self-heal, etc.?

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Application CRD vs Kubernetes Manifests

Concept	Argo CD Application CRD	Kubernetes Manifests
Kind	Application	Deployment, Service, ConfigMap, Secret, etc.
Purpose	a contract for Argo CD to manage set of Kubernetes manifests.	resources of the running application.
Information Included	Source, Destination,sync policy	container image, ports, replicas
Where in the Cluster	Usually in the argocd namespace.	In the target application namespace
Who Cares About It?	Argo CD controllers.	Kubernetes controllers

---

Supported Tools

• Helm charts
• Kustomize application
• Directory of Yaml files.

• Jsonnet

• Auto Detected
  • Helm charts : if there is a file as Chart.yaml
  • Kustomize: if there’s a kustomization.yaml, kustomization.yml, or Kustomization
  • Otherwise it is assumed to be a plain Yaml directory application

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Common Commands

• Get app info

Command	Description
argocd app list	List all Argo CD applications.
argocd app get <app_name>	Show detailed information about one application
argocd app logs <app_name>	Show logs from pods that belong to the application.
argocd app resources <app_name>	Show Kubernetes resources managed by the application.
argocd app manifests <app_name>	Show the rendered Kubernetes manifests generated by Argo CD.

• Common operations

Command	Description
argocd app diff <app_name>	Compare the desired state in Git with the live state in Kubernetes.
argocd app sync <app_name>	Manually sync the application from Git to the Kubernetes cluster.
argocd app refresh <app_name>	Ask Argo CD to refresh the application state from Git and the cluster.
argocd app set <app_name>	Update application settings
argocd app unset <app_name>	Remove specific application parameters or settings.
argocd app history <app_name>	Show the deployment history of an application.
argocd app rollback <app_name> <history-id>	Roll back the application to a previous deployment revision.
argocd app wait <app_name>	Wait until an application becomes synced, healthy, or degraded. Useful in CI/CD pipelines.
argocd app actions list <app_name>	List available resource actions for the application.
argocd app actions run <app_name> <action>	Run an action against an application resource.
argocd app terminate-op <app_name>	Stop a running sync, rollback, or other application operation.
argocd app delete <app_name>	Delete an Argo CD application.

• Create App

Command	Description
argocd app create <app_name> --repo <repo_url> --path <path> --dest-namespace <ns> --dest-server <k8s_server> --directory-recurse	Create a directory app
argocd app create <app_name> --repo <repo_url> --path <helm_path> --dest-namespace <ns> --dest-server <dest_server> --helm-set replicaCount=2	Create a Helm app
argocd app create <app_name> --repo <repo_url> --helm-chart <chart_name> --revision <revision> --dest-namespace <ns> --dest-server <dest_server>	Create a Helm app from a Helm repo
argocd app create <app_name> --repo <repo_url> --path <manifest_path> --dest-namespace <ns> --dest-server <dest_server> --kustomize-image <image>	Create a Kustomize app
argocd app create <app_name> --file <path-to-yaml-file>	Create app from a yaml file

---

Lab: Create Application

Method: Ddeclarative

# ArgoCD CRD
apiVersion: argoproj.io/v1alpha1
kind: Application
# meta data
metadata:
  name: guestbook
  namespace: argocd
spec:
  project: default

  # source of manifests
  source:
    repoURL: "https://github.com/argoproj/argocd-example-apps.git"
    targetRevision: HEAD
    path: guestbook

  # destination cluster
  destination:
    server: "https://kubernetes.default.svc"
    namespace: guestbook

kubectl create namespace guestbook
# namespace/guestbook created

kubectl apply -f demo_app.yaml
# application.argoproj.io/guestbook created

• Confirm

argocd app list
# NAME              CLUSTER                         NAMESPACE  PROJECT  STATUS     HEALTH   SYNCPOLICY  CONDITIONS  REPO                                                 PATH       TARGET
# argocd/guestbook  https://kubernetes.default.svc  guestbook  default  OutOfSync  Missing  Manual      <none>      https://github.com/argoproj/argocd-example-apps.git  guestbook  HEAD

argocd app get guestbook
# Name:               argocd/guestbook
# Project:            default
# Server:             https://kubernetes.default.svc
# Namespace:          guestbook
# URL:                https://argocd.example.com/applications/guestbook
# Source:
# - Repo:             https://github.com/argoproj/argocd-example-apps.git
#   Target:           HEAD
#   Path:             guestbook
# SyncWindow:         Sync Allowed
# Sync Policy:        Manual
# Sync Status:        OutOfSync from HEAD (723b86e)
# Health Status:      Missing

# GROUP  KIND        NAMESPACE  NAME          STATUS     HEALTH   HOOK  MESSAGE
#        Service     guestbook  guestbook-ui  OutOfSync  Missing
# apps   Deployment  guestbook  guestbook-ui  OutOfSync  Missing

argocd app sync guestbook
# TIMESTAMP                  GROUP        KIND   NAMESPACE                  NAME    STATUS    HEALTH        HOOK  MESSAGE
# 2026-04-27T16:23:14-04:00            Service   guestbook          guestbook-ui  OutOfSync  Missing
# 2026-04-27T16:23:14-04:00   apps  Deployment   guestbook          guestbook-ui  OutOfSync  Missing
# 2026-04-27T16:23:14-04:00            Service   guestbook          guestbook-ui  OutOfSync  Missing              service/guestbook-ui created
# 2026-04-27T16:23:14-04:00   apps  Deployment   guestbook          guestbook-ui  OutOfSync  Missing              deployment.apps/guestbook-ui created
# 2026-04-27T16:23:14-04:00            Service   guestbook          guestbook-ui    Synced  Healthy                  service/guestbook-ui created
# 2026-04-27T16:23:14-04:00   apps  Deployment   guestbook          guestbook-ui    Synced  Progressing              deployment.apps/guestbook-ui created

# Name:               argocd/guestbook
# Project:            default
# Server:             https://kubernetes.default.svc
# Namespace:          guestbook
# URL:                https://argocd.example.com/applications/guestbook
# Source:
# - Repo:             https://github.com/argoproj/argocd-example-apps.git
#   Target:           HEAD
#   Path:             guestbook
# SyncWindow:         Sync Allowed
# Sync Policy:        Manual
# Sync Status:        Synced to HEAD (723b86e)
# Health Status:      Progressing

# Operation:          Sync
# Sync Revision:      723b86e01bea11dcf72316cb172868fcbf05d69e
# Phase:              Succeeded
# Start:              2026-04-27 16:23:14 -0400 EDT
# Finished:           2026-04-27 16:23:14 -0400 EDT
# Duration:           0s
# Message:            successfully synced (all tasks run)

# GROUP  KIND        NAMESPACE  NAME          STATUS  HEALTH       HOOK  MESSAGE
#        Service     guestbook  guestbook-ui  Synced  Healthy            service/guestbook-ui created
# apps   Deployment  guestbook  guestbook-ui  Synced  Progressing        deployment.apps/guestbook-ui created

# wait for sync and health
argocd app wait guestbook --health --sync
# TIMESTAMP                  GROUP        KIND   NAMESPACE                  NAME    STATUS   HEALTH            HOOK  MESSAGE
# 2026-04-27T16:23:41-04:00            Service   guestbook          guestbook-ui    Synced  Healthy                  service/guestbook-ui created
# 2026-04-27T16:23:41-04:00   apps  Deployment   guestbook          guestbook-ui    Synced  Progressing              deployment.apps/guestbook-ui created

# Name:               argocd/guestbook
# Project:            default
# Server:             https://kubernetes.default.svc
# Namespace:          guestbook
# URL:                https://argocd.example.com/applications/guestbook
# Source:
# - Repo:             https://github.com/argoproj/argocd-example-apps.git
#   Target:           HEAD
#   Path:             guestbook
# SyncWindow:         Sync Allowed
# Sync Policy:        Manual
# Sync Status:        Synced to HEAD (723b86e)
# Health Status:      Healthy


# GROUP  KIND        NAMESPACE  NAME          STATUS  HEALTH   HOOK  MESSAGE
#        Service     guestbook  guestbook-ui  Synced  Healthy        service/guestbook-ui created
# apps   Deployment  guestbook  guestbook-ui  Synced  Healthy        deployment.apps/guestbook-ui created

• Delete

argocd app delete guestbook
# Are you sure you want to delete 'guestbook' and all its resources? [y/n] y
# application 'guestbook' deleted

argocd app list
# NAME  CLUSTER  NAMESPACE  PROJECT  STATUS  HEALTH  SYNCPOLICY  CONDITIONS  REPO  PATH  TARGET

---

Method: CLI

argocd app list
# NAME  CLUSTER  NAMESPACE  PROJECT  STATUS  HEALTH  SYNCPOLICY  CONDITIONS  REPO  PATH  TARGET

argocd app create guestbook-1 \
  --project default     \
  --repo https://github.com/argoproj/argocd-example-apps.git \
  --path guestbook \
  --dest-server https://kubernetes.default.svc \
  --dest-namespace guestbook

# application 'guestbook-1' created
argocd app sync guestbook-1
argocd app get guestbook-1

argocd app delete guestbook-1
# Are you sure you want to delete 'guestbook-1' and all its resources? [y/n] y
# application 'guestbook-1' deleted

---

Method: UI

• app name: guestbook-2
• Project Name: default
• SOURCE
  • url: https://github.com/argoproj/argocd-example-apps.git
  • Path: guestbook
• DESTINATION
  • Cluster URL: https://kubernetes.default.svc
  • Namespace: guestbook

• Delete

---

Tools: Helm

• Supported helm source:
  • Git Repo.
  • Helm Repo.

---

• Example: git repo

source:
  path: path_name
  repoURL: "git_url"
  targetRevision: HEAD

---

• Example: Helm Repo

source:
  chart: chart_name
  repoURL: "helm_url"
  targetRevision: chart_version

---

Common Options

• source.helm.releaseName: string, Release name
• source.helm.valuesFiles: list, Values files.

• source.helm.parameters: key-value list, Parameters.

  helm:
    parameters:
      - name: "service.type"
        value: "LoadBalancer"
      - name: "image.tag"
        value: "v"
  

• source.helm.fileParameters: key-value list, File parameters.

  helm:
  fileParameters: - name: config
  value: files/config.json
  

• source.helm.values: string, Values as block

  helm:
    values: |
      ingress:
        enabled: true
        path: /
        hosts:
          - mydomain.example.com
  

---

Lab: Create App with Helm

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: helm-app
  namespace: argocd
spec:
  project: default
  destination:
    server: "https://kubernetes.default.svc"
    namespace: helm-app
  source:
    repoURL: "https://github.com/argoproj/argocd-example-apps.git"
    path: helm-guestbook
    targetRevision: master
    helm:
      # release name
      releaseName: helm-guestbook
  syncPolicy:
    syncOptions:
      - CreateNamespace=true

kubectl apply -f demo_app_helm.yaml
# application.argoproj.io/helm-app created

argocd app list
# NAME             CLUSTER                         NAMESPACE  PROJECT  STATUS     HEALTH   SYNCPOLICY  CONDITIONS  REPO                                                 PATH            TARGET
# argocd/helm-app  https://kubernetes.default.svc  helm-app   default  OutOfSync  Missing  Manual      <none>      https://github.com/argoproj/argocd-example-apps.git  helm-guestbook  master

argocd app delete helm-app
# Are you sure you want to delete 'helm-app' and all its resources? [y/n] y
# application 'helm-app' de

Tools: Directory manifests

• Options:
  • directory.recurse:
    • true: Recursive, include all files in sub-directories.
  • directory.jsonnet.extVars:
    • External Vars : list of external variables for Jsonnet.
  • directory.jsonnet.tlas:
    • Top level Arguments

---

• example:

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: dir-app
  namespace: argocd
spec:
  project: default
  destination:
    server: "https://kubernetes.default.svc"
    namespace: dir-app
  source:
    repoURL: "https://github.com/argoproj/argocd-example-apps.git"
    targetRevision: master
    path: apps
    # dir
    directory:
      recurse: true
  syncPolicy:
    syncOptions:
      - CreateNamespace=true

---

Tools: Kustomize

• kustomizekey:
  • namePrefix: overrides the namePrefix in the kustomization.yaml for Kustomize apps
  • nameSuffix: overrides the nameSuffix in the kustomization.yaml for Kustomize apps
  • images: a list of Kustomize image overrides
  • replicas: a list of Kustomize replica overrides
  • commonLabels: a string map of additional labels
  • commonAnnotations: string map of additional annotations
  • version: explicitly set kustomize version.

---

Lab: Create App with Kustomize

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: kustomize-app
  namespace: argocd
spec:
  project: default
  destination:
    server: "https://kubernetes.default.svc"
    namespace: kustomize-app
  source:
    repoURL: "https://github.com/argoproj/argocd-example-apps.git"
    targetRevision: master
    path: kustomize-guestbook
    # kustomize
    kustomize:
      namePrefix: staging-
      commonLabels:
        app: demo
  syncPolicy:
    syncOptions:
      - CreateNamespace=true

kubectl apply -f demo_kustomize.yaml
# application.argoproj.io/kustomize-app created

---

Tools: Multiple Sources

• Craete application stored in multiple repositories

• Use cases:

  • remote helm chart + git-hosted values file
    • e.g., nginx helm chart from helm repo + values.yaml from git

---

Tracking Strategies

• Git repos tracking:
  • Commit SHA (good for production).
  • Tags (good for production).
  • Branch tracking (ex: main branch).
  • Symbolic reference (HEAD).
• Helm repos tracking : Helm always use semantic versioning
  • Specific version v1.2
  • Range 1.2.* or >=1.2.0 <1.3.0.
  • Latest * or >=0.0.0

---

• Sample

# git: tag name
spec:
  source:
    path: guestbook
    repoURL: "https://github.com/mabusaa/argocd-example-apps.git"
    targetRevision: v1 # tag name

# git: sha value
spec:
  source:
    repoURL: "https://github.com/mabusaa/argocd-example-apps.git"
    targetRevision: 2455bb6 # using the short commit id

# git: branch name
spec:
  source:
    repoURL: "https://github.com/mabusaa/argocd-example-apps.git"
    targetRevision: main  # branch name

# git: symbolic reference
spec:
  source:
    repoURL: "https://github.com/mabusaa/argocd-example-apps.git"
    targetRevision: HEAD  # symbolic reference

# Helm: symbolic reference
spec:
  source:
    chart: sealed-secret
    repoURL: "https://bitnami-labs.github.io/sealed-secrets"
    targetRevision: 1.16.1   # symbolic reference

# Helm: Range
spec:
  source:
    chart: sealed-secret
    repoURL: "https://bitnami-labs.github.io/sealed-secrets"
    targetRevision: '>=3.0.0 <4.1.0' # symbolic reference

# Helm: Latest version
spec:
  source:
    chart: sealed-secret
    repoURL: "https://bitnami-labs.github.io/sealed-secrets"
    targetRevision: *   # Latest version

---