Deploying a Flask App to GCP using Docker and CI/CD

Step 1: Create requirements.txt

First, list the dependencies for your Flask application in a requirements.txt file:

Flask==2.0.3        

Step 2: Create Dockerfile

Next, create a Dockerfile to containerize your Flask application. Below is an example:

Step 3: Update Flask App to Listen on Port 8080

In your app.py, ensure your Flask app listens on port 8080:

if __name__ == '__main__':
    app.run(host="0.0.0.0", port=8080)  # Hardcoded port 8080        

Error Handling: If the port is not configured correctly, you may encounter the following error when deploying:

Revision 'flaskimg-00001-nqv' is not ready and cannot serve traffic. The user-provided container failed to start and listen on the port defined provided by the PORT=8080 environment variable within the allocated timeout.        

Ensure your app is configured to listen on port 8080, as GCP expects it.

Step 4: Create a New GCP Project

Create a new project in GCP, for example, flaskdeploydocker. Obtain the project ID for further use.

Step 5: Enable Cloud Run API and Cloud Build

You need to enable Cloud Run and Cloud Build APIs in your project. You can do this in the GCP Console, and ensure billing is enabled.

Step 6: Install Google Cloud CLI

Install the gcloud CLI tool and initialize it:

gcloud init
gcloud config set project flaskdockerdeploy        

Step 7: Create Artifact Repository

Create a Docker repository in Google Artifact Registry:

gcloud artifacts repositories create flaskdocker --repository-format=docker --location=europe-west4 --description="FlaskDockerAPP" --immutable-tags --async        

Step 8: Authenticate Docker to GCP

Authenticate Docker to GCP's Artifact Registry:

gcloud auth configure-docker europe-west4-docker.pkg.dev        

Step 9: Configure IAM Permissions

In IAM, assign the Object Storage Viewer permission to the service account to allow access to the Artifact Registry.

Step 10: Build and Push Docker Image

Build and push the Docker image to Artifact Registry:

gcloud builds submit --tag europe-west4-docker.pkg.dev/flaskdockerdeploy/flaskdocker/flaskimg:flasktagnew        

Step 11: Deploy to Cloud Run

1. Go to the Cloud Run console.
2. Select Deploy Container -> Service.
3. Choose the container image from Artifact Registry.
4. Allow unauthenticated invocations if you want your service to be publicly accessible.

Step 12: Set up CI/CD Pipeline with GitHub

To automate deployments, connect your GitHub repository to GCP and set up a CI/CD pipeline using Cloud Build to push images to Artifact Registry and deploy them to Cloud Run.

Step 13: Run Locally Using Docker

If you want to run the application locally using Docker, build and run it using the following commands:

docker build . --tag europe-west4-docker.pkg.dev/flaskdockerdeploy/flaskdocker/otherimg:othertag
docker run -p 8080:8080 europe-west4-docker.pkg.dev/flaskdockerdeploy/flaskdocker/otherimg:othertag        

Gonna ship my next all apps using docker + gcp - Why? Because i have free credits of gcp (due to hackathon wins)