Deploying FastAPI in Azure

Question

I am trying to deploy my application which is built using Python and FastAPI for backend and the HTML for the frontend.

Using the student login i created an app service and uploaded my code using github.

My project directory is like

Frontend/
|- file.html
|- x.css
FastAPI/
|- main.py
|- other.py
|- requirements.txt

in my .yml files, I changed the directory of the requirements.txt and package in deploy to ./fastAPI. But the website url shows the following message.

Hey, Python developers!

Your app service is up and running. Time to take the next step and deploy your code.

And it displays the error message in github workflow

Deployment Failed, Error: Failed to deploy web package to App Service. Conflict (CODE: 409)

I tried to use startup-command in the yml file to start the FastAPI, it didn't work and gave the following error message

Deployment Failed, Error: startup-command is not a valid input for Windows web app or with publish-profile auth scheme.

I changed the configuration on the azure portal to add WEBSITES_CONTAINER_STARTUP_COMMAND = uvicorn main:app --host 0.0.0.0 --port 80 in the application settings, didn't work.

Answer 1

I have deployed a simple Fast API project with HTML and CSS as frontend:

My project structure:

- FastAPI
    - templates
        - index.html
    -static
        - style.css
    - main.py
    - requirements.txt

• Create Azure App Service with Python as Runtime stack, Linux as OS and Consumption hosting Plan in Azure Portal:

• Configure Deployment during the creation of App Service.

• Click on Review+Create.
• Once the App Service gets created, it will generate the workflow in your GitHub repository, and it starts the deployment.
• Deployment status can be tracked in your GitHub repository=>Actions.

My Workflow to deploy FastAPI:

name: Build and deploy Python app to Azure Web App - <web_app_Name>

on:
  push:
    branches:
      - main
  workflow_dispatch:

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v2

      - name: Set up Python version
        uses: actions/setup-python@v1
        with:
          python-version: '3.10'

      - name: Create and start virtual environment
        run: |
          python -m venv venv
          source venv/bin/activate
      
      - name: Install dependencies
        run: pip install -r requirements.txt
        
      # Optional: Add step to run tests here (PyTest, Django test suites, etc.)
      
      - name: Upload artifact for deployment jobs
        uses: actions/upload-artifact@v2
        with:
          name: python-app
          path: |
            . 
            !venv/
  deploy:
    runs-on: ubuntu-latest
    needs: build
    environment:
      name: 'Production'
      url: ${{ steps.deploy-to-webapp.outputs.webapp-url }}

    steps:
      - name: Download artifact from build job
        uses: actions/download-artifact@v2
        with:
          name: python-app
          path: .
          
      - name: 'Deploy to Azure Web App'
        uses: azure/webapps-deploy@v2
        id: deploy-to-webapp
        with:
          app-name: '<web_app_Name>'
          slot-name: 'Production'
          publish-profile: ${{ secrets.AZUREAPPSERVICE_PUBLISHPROFILE_XXXXXXXXXXX }}
Ad

Deployed Successfully:

You have to run the Startup command for FastAPI in App Service=>Settings=>Configuration: gunicorn --bind=0.0.0.0 main:app

• main is from the filename main.py and app is the object which I used in main.py.

References:

Refer my SO thread on the similar issue.