GitOps with ArgoCD in Kubernetes - Step-by-Step Execution

Process Flow - GitOps with ArgoCD

Developer pushes code to Git repo

↓

ArgoCD monitors Git repo

↓

Detects changes in repo

↓

ArgoCD syncs changes to Kubernetes cluster

↓

Kubernetes applies new config/state

↓

Cluster state matches Git repo state

↓

ArgoCD reports status back

This flow shows how ArgoCD watches a Git repository for changes, then applies those changes automatically to a Kubernetes cluster, keeping cluster state in sync with Git.

Execution Sample

Kubernetes

kubectl create namespace argocd
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml
argocd app create guestbook --repo https://github.com/argoproj/argocd-example-apps.git --path guestbook --dest-server https://kubernetes.default.svc --dest-namespace default
argocd app sync guestbook

This sequence installs ArgoCD, creates an application linked to a Git repo, and syncs it to the Kubernetes cluster.

Process Table

Step	Action	Evaluation	Result
1	Create namespace 'argocd'	Namespace 'argocd' does not exist	Namespace 'argocd' created
2	Apply ArgoCD manifests	Manifests valid	ArgoCD components deployed in 'argocd' namespace
3	Create ArgoCD app 'guestbook'	Repo and path accessible	App 'guestbook' registered in ArgoCD
4	ArgoCD monitors Git repo	No changes yet	App status: Synced
5	Push change to Git repo (e.g., update guestbook image)	Change detected by ArgoCD	App status: OutOfSync
6	Run 'argocd app sync guestbook'	Sync command accepted	Cluster updated to match Git repo
7	Verify app status	Cluster matches Git repo	App status: Synced
8	Exit	No further changes	Process waits for next Git change

💡 No new changes in Git repo, ArgoCD waits for updates

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 5	After Step 6	Final
Namespace 'argocd'	Not present	Created	Exists	Exists	Exists	Exists	Exists
ArgoCD app 'guestbook' status	Not present	Not present	Not present	Synced	OutOfSync	Synced	Synced
Cluster state	Old config	Old config	Old config	Old config	Old config	Updated to Git state	Updated to Git state

Key Moments - 3 Insights

Why does ArgoCD show 'OutOfSync' after I push changes to Git?

Because ArgoCD detects that the cluster state no longer matches the Git repo state (see execution_table step 5). It waits for a sync command or automatic sync to update the cluster.

What happens if I don't run 'argocd app sync' after pushing changes?

The cluster remains out of sync with Git repo (execution_table step 5). ArgoCD will not apply changes until sync is triggered manually or auto-sync is enabled.

Why do we create a separate namespace 'argocd' before installing ArgoCD?

Namespaces isolate resources in Kubernetes. Creating 'argocd' namespace (step 1) keeps ArgoCD components organized and separate from other apps.

Visual Quiz - 3 Questions

Look at the execution_table at step 5, what is the ArgoCD app 'guestbook' status?

A OutOfSync

B Unknown

C Synced

D Error

💡 Hint

Check the 'Result' column at step 5 in the execution_table.

At which step does the Kubernetes cluster update to match the Git repo?

A Step 5

B Step 6

C Step 3

D Step 7

💡 Hint

Look for the step where 'Cluster updated to match Git repo' appears in the execution_table.

If you skip creating the 'argocd' namespace, what will happen at step 2?

A ArgoCD installs in default namespace

B Namespace is created automatically

C Installation fails due to missing namespace

D ArgoCD installs but with errors

💡 Hint

Refer to variable_tracker for 'Namespace argocd' status after step 1 and step 2.

Concept Snapshot

GitOps with ArgoCD:
- ArgoCD watches Git repo for changes
- Changes trigger sync to Kubernetes cluster
- Cluster state matches Git repo state
- Use 'argocd app sync' to apply changes
- Namespace isolates ArgoCD components
- Status shows sync state (Synced/OutOfSync)

Full Transcript

GitOps with ArgoCD means using Git as the single source of truth for Kubernetes configurations. Developers push changes to a Git repository. ArgoCD continuously monitors this repo. When it detects changes, it marks the application as OutOfSync. Running 'argocd app sync' applies those changes to the Kubernetes cluster, updating it to match the Git state. The cluster then reports back as Synced. ArgoCD runs in its own namespace for organization. This process automates deployment and keeps cluster state consistent with Git.

Practice

1. What is the main purpose of using ArgoCD in a Kubernetes environment with GitOps?

easy

A. To replace Kubernetes with a new container orchestration system

B. To manually deploy applications without using Git

C. To store container images in a private registry

D. To automatically sync Kubernetes cluster state with Git repository configurations

Solution

1. Step 1: Understand GitOps concept

   GitOps uses Git as the single source of truth for application configurations.

2. Step 2: Role of ArgoCD in GitOps

   ArgoCD automatically syncs Kubernetes cluster state to match the Git repo, ensuring deployments are consistent and automated.

3. Final Answer:

   To automatically sync Kubernetes cluster state with Git repository configurations -> Option D

4. Quick Check:

   GitOps = Auto-sync cluster with Git [OK]

Hint: Remember: ArgoCD syncs cluster state from Git automatically [OK]

Common Mistakes:

• Thinking ArgoCD replaces Kubernetes
• Believing ArgoCD deploys apps manually
• Confusing ArgoCD with container registries

2. Which of the following is the correct ArgoCD CLI command to create an application named myapp syncing from Git repo https://github.com/example/repo.git with path k8s and target cluster https://kubernetes.default.svc?

easy

A. argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default

B. argocd create app myapp --repository https://github.com/example/repo.git --directory k8s --cluster https://kubernetes.default.svc

C. kubectl create app myapp --repo https://github.com/example/repo.git --path k8s

D. argocd app new myapp --repo-url https://github.com/example/repo.git --folder k8s --server https://kubernetes.default.svc

Solution

1. Step 1: Identify correct ArgoCD CLI syntax

   The correct command uses argocd app create with flags --repo, --path, --dest-server, and --dest-namespace.

2. Step 2: Compare options

   argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default matches the official syntax exactly. Others use incorrect commands or flags.

3. Final Answer:

   argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default -> Option A

4. Quick Check:

   Correct CLI syntax = argocd app create myapp --repo https://github.com/example/repo.git --path k8s --dest-server https://kubernetes.default.svc --dest-namespace default [OK]

Hint: Remember: 'argocd app create' plus repo, path, dest-server flags [OK]

Common Mistakes:

• Using kubectl instead of argocd CLI
• Wrong flag names like --repository or --folder
• Incorrect command order or missing --dest-namespace

3. Given the following ArgoCD Application YAML snippet, what will happen when ArgoCD syncs this app?

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: sample-app
spec:
  source:
    repoURL: https://github.com/example/app-configs.git
    path: production
  destination:
    server: https://kubernetes.default.svc
    namespace: default
  syncPolicy:
    automated: {}

medium

A. ArgoCD will reject the app because syncPolicy is empty

B. ArgoCD will only show the app status but not deploy it automatically

C. ArgoCD will automatically deploy and keep the app in sync with the Git repo

D. ArgoCD will deploy the app once but not update it on Git changes

Solution

1. Step 1: Understand syncPolicy automated

   The syncPolicy: automated: {} means ArgoCD will auto-sync changes from Git to cluster.

2. Step 2: Effect on deployment

   ArgoCD will deploy the app initially and keep it updated automatically when Git changes.

3. Final Answer:

   ArgoCD will automatically deploy and keep the app in sync with the Git repo -> Option C

4. Quick Check:

   syncPolicy automated = auto deploy and sync [OK]

Hint: syncPolicy automated means auto deploy and keep in sync [OK]

Common Mistakes:

• Thinking empty braces mean no automation
• Assuming manual sync is required
• Confusing syncPolicy with app rejection

4. You created an ArgoCD app but it shows OutOfSync status even after you committed changes to Git. Which of the following is the most likely cause?

medium

A. The app's syncPolicy is not set to automated, so manual sync is needed

B. The Git repository URL is incorrect and unreachable

C. The Kubernetes cluster is down and cannot apply changes

D. The app name in ArgoCD does not match the Git repo name

Solution

1. Step 1: Understand OutOfSync status

   OutOfSync means cluster state differs from Git repo state.

2. Step 2: Check syncPolicy effect

   If syncPolicy is not automated, ArgoCD won't auto-apply changes; manual sync is required.

3. Final Answer:

   The app's syncPolicy is not set to automated, so manual sync is needed -> Option A

4. Quick Check:

   OutOfSync + no automated sync = manual sync needed [OK]

Hint: OutOfSync often means no automated sync set [OK]

Common Mistakes:

• Assuming cluster is down without checking
• Blaming Git URL without error evidence
• Thinking app name mismatch causes OutOfSync

5. You want to ensure that ArgoCD only deploys changes to your Kubernetes cluster after manual approval, but still track changes in Git automatically. Which configuration should you use in your ArgoCD Application YAML?

hard

A. Set syncPolicy: automated: {} to enable auto deploy

B. Omit syncPolicy and use manual sync to approve changes

C. Set syncPolicy: automated: null to disable auto deploy

D. Set syncPolicy: automated: { prune: true, selfHeal: true } for auto deploy with cleanup

Solution

1. Step 1: Understand manual approval need

   To require manual approval before deployment, auto sync must be disabled.

2. Step 2: Configure syncPolicy accordingly

   Omitting syncPolicy disables auto sync, so ArgoCD tracks Git but waits for manual sync.

3. Final Answer:

   Omit syncPolicy and use manual sync to approve changes -> Option B

4. Quick Check:

   No syncPolicy = manual approval required [OK]

Hint: No syncPolicy means manual sync only [OK]

Common Mistakes:

• Using automated sync disables manual approval
• Setting automated with prune/selfHeal still auto deploys
• Setting automated: null is invalid syntax