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Deploy a Python Flask App

Deploy a Python Flask application on Koyeb and benefit from Koyeb native autoscaling, automatic HTTPS (SSL), auto-healing, and global load-balancing across our edge network with zero configuration.

This guide explains how to deploy a Python Flask application on Koyeb using:

  1. Git-driven deployment to automatically build and deploy a new version of your application each time a change is detected on your branch.
  2. Pre-built containers you can deploy from any public or private registry.

To successfully follow this documentation, you will need to have a Koyeb account. You can optionally install the Koyeb CLI if you prefer to follow this guide without leaving the terminal.

You can deploy and preview the sample Python Flask application that we will run on Koyeb in this guide using the Deploy to Koyeb button below.

Deploy to Koyeb

You can access the repository used for this documentation here.

Create the Python Flask app

Get started by creating a minimalistic Python Flask application that we will deploy on Koyeb. You will need Python installed on your machine.

In your terminal, run the following commands to create the directory that will hold the application code:

mkdir example-flask
cd example-flask

In the folder you created, create a new virtual environment folder using python -m venv venv. Virtual environments provide isolation from the system environment allowing each virtual environment you create to have its own installation directories, dependencies, etc. Then to activate and load your virtual environment, type:

. venv/bin/activate

Install Flask and create the requirements.txt to store the dependencies and version of each package required to run our application.

pip install flask gunicorn
pip freeze > requirements.txt

Create a new file app.py to store our minimalist Flask application code. In the snipper below, we define a route to handle / request and return "Hello from Koyeb" as a response.

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello from Koyeb'


if __name__ == "__main__":
    app.run()

Run the Python Flask app locally

Launch the application locally to make sure everything is running as expected.

gunicorn app:app

You can now access the application at http://localhost:8000.

Deploy the Python Flask app on Koyeb using git-driven deployment

In the project directory, initialize a new git repository by running the following command:

git init

We will use this repository to version the application code and push the changes to a GitHub repository. If you don't have an existing GitHub repository to push the code to, you can create a new one and run the following commands to commit and push changes to your GitHub repository:

git add requirements.txt app.py
git commit -m "Initial commit"
git remote add origin git@github.com:<YOUR_GITHUB_USERNAME>/<YOUR_REPOSITORY_NAME>.git
git push -u origin main

Via the Koyeb control panel

To deploy the Python Flask app on Koyeb, using the control panel follow the steps below:

  1. Create a new Koyeb App named example-python
  2. Select GitHub as the deployment option
  3. Choose the GitHub repository and branch contaning your application code
  4. Name your service, for instance python-service
  5. Click the Create service button.

A Koyeb App and Service have been created. Your application is now going to be built and deployed on Koyeb. Once the build has finished, you will be able to access your application running on Koyeb by clicking the URL ending with .koyeb.app.

Via Koyeb CLI

To deploy the Python Flask app on Koyeb using the Koyeb CLI, run the following command in your terminal:

koyeb app init example-python \
  --git github.com/<YOUR_GITHUB_USERNAME>/<YOUR_REPOSITORY_NAME> \
  --git-branch main \
  --ports 8080:http \
  --routes /:8080 \
  --env PORT=8080

Make sure to replace <YOUR_GITHUB_USERNAME>/<YOUR_REPOSITORY_NAME> with your GitHub username and repository name.

Access deployment logs

To track the app deployment and visualize build logs, execute the following command:

koyeb service logs example-python/example-python -t build

Access your app

Once the deployment of your application has finished, you can retrieve the public domain to access your application by running the following command:

$ koyeb app get example-python
ID      	NAME         	DOMAINS                          	CREATED AT
55d75993	example-python	["example-python-myorg.koyeb.app"]	20 Sep 22 09:55 UTC

Access runtime logs

With your app running, you can track the runtime logs by running the following command:

koyeb service logs example-python/example-python -t runtime

Deploy the Python Flask app on Koyeb using a pre-built container

Alternatively to using git-driven deployment, you can deploy a pre-built container from any public or private registry. This can be useful if your application needs specific system dependencies or you need more control over how the build is performed.

To dockerize the Python Flask application, create a Dockerfile in your project root directory and copy the content below:

FROM python:3-alpine AS builder

WORKDIR /app

RUN python3 -m venv venv
ENV VIRTUAL_ENV=/app/venv
ENV PATH="$VIRTUAL_ENV/bin:$PATH"

COPY requirements.txt .
RUN pip install -r requirements.txt

# Stage 2
FROM python:3-alpine AS runner

WORKDIR /app

COPY --from=builder /app/venv venv
COPY app.py app.py

ENV VIRTUAL_ENV=/app/venv
ENV PATH="$VIRTUAL_ENV/bin:$PATH"
ENV FLASK_APP=app/app.py

EXPOSE 8080

CMD ["gunicorn", "--bind" , ":8080", "--workers", "2", "app:app"]

The Dockerfile above provides the minimum requirements to run the Python Flask application. You can easily extend it depending on your needs.

To build and push the Docker image to a registry and deploy it on Koyeb, refer to the Deploy an app from a Docker image.

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