Simple CI/CD school project: GitHub Actions → Docker Hub → Argo CD → Kubernetes

This repo uses a minimal GitOps workflow:

1. GitHub Actions builds a Docker image on every push
2. The image is pushed to Docker Hub with a unique tag (the commit SHA)
3. The workflow updates the Kubernetes manifest to reference that new image tag
4. Argo CD detects the manifest change in Git and deploys automatically to your local Kubernetes cluster

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1) Docker Hub

• Create a Docker Hub repository (example: docker.io/<your-user>/flask-app)
• Create a Docker Hub Access Token

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2) GitHub Secrets

In GitHub: Settings → Secrets and variables → Actions

Add:

• DOCKERHUB_USERNAME
• DOCKERHUB_TOKEN

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3) Kubernetes / Argo CD (one-time setup)

Install Argo CD

kubectl create namespace argocd
kubectl apply -n argocd -f https://raw.githubusercontent.com/argoproj/argo-cd/stable/manifests/install.yaml

Create the target namespace for the app

kubectl create namespace flask-app

Open Argo CD UI

kubectl -n argocd port-forward svc/argocd-server 8080:443

Open https://localhost:8080

Get the admin password (PowerShell):

$pw_b64 = kubectl -n argocd get secret argocd-initial-admin-secret -o jsonpath="{.data.password}"
[Text.Encoding]::UTF8.GetString([Convert]::FromBase64String($pw_b64))

Create an Argo CD Application (GUI)

In Argo CD:

• New App
• Repo URL: your GitHub repo
• Revision: main
• Path: k8s
• Destination namespace: flask-app
• Sync policy: Automated

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4) GitHub Actions workflow

On every push to main:

• builds the Docker image
• pushes it to Docker Hub as:
  docker.io/<your-user>/flask-app:<commit-sha>
• updates the manifest in k8s/ to use that new SHA tag
• commits and pushes the manifest update back to main

Argo CD sees the new commit and deploys it.

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Using it

1. Make a change to the app (even just a color/text change)
2. Commit and push to main
3. Watch GitHub Actions run
4. After a short delay, Argo CD deploys automatically

If you exposed the app as NodePort 30080, you can access it at:

• http://localhost:30080

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Note about delays

On a local cluster, Argo CD usually checks Git every few minutes.
You can also press Refresh in the Argo CD UI to make it check immediately.