Cannot deploy python with webapp to azure on python 3.8

Question

I am trying to deploy a test project using the Flask framework into the azure cloud using the Azure CLI

https://learn.microsoft.com/en-us/azure/app-service/containers/quickstart-python?tabs=bash

https://learn.microsoft.com/en-us/azure/app-service/containers/how-to-configure-python

There are some issues regarding the runtime_version of my app. Everytime I try to run the command for deploying it tries to upgrade the runtime_version to the python|3.7 even if I set it to the python|3.8 in the settings and then the deployment fails. It has to be set to python|3.7 to be succesfully deployed.

The app is quite simple:

from flask import Flask
from markupsafe import escape

app = Flask(__name__)

@app.route('/')
def index():
    return 'Index page'

@app.route('/hello')
def hello_world():
    return 'Hello, World!!!'

@app.route('/user/<username>')
def show_user_profile(username):
    # show the user profile for that user
    return 'User %s' % escape(username)

@app.route('/post/<int:post_id>')
def show_post(post_id):
    # show the post with the given id, the id is an int
    return 'Post %d' % post_id

@app.route('/path/<path:subpath>')
def show_subpath(subpath):
    # show the subpath after /path/
    return 'Subpath %s' % escape(subpath)

@app.route('/projects/')
def projects():
    return 'The project page'

@app.route('/about')
def about():
    return 'The about page'

I also created a requirements.txt file with the required packages as recommended in the microsoft documentation.

click==7.1.2
flask==1.1.2
itsdangerous==1.1.0
jinja2==2.11.2
markupsafe==1.1.1
werkzeug==1.0.1

And this is the command I used to deploy the application the first time

az webapp up --sku F1 -l westeurope -n XXXXXX-blf

Output:

(venv) D:\dev\FlaskTesting [master ≡ +4 ~0 -1 !]> az webapp up --sku F1 -l westeurope -n XXXXXX-blf
webapp XXXXXX-blf doesn't exist
Creating Resource group 'InsaneSpeech_rg_Linux_westeurope' ...
Resource group creation complete
Creating AppServicePlan 'InsaneSpeech_asp_Linux_westeurope_0' ...
Creating webapp 'XXXXXX-blf' ...
Creating zip with contents of dir D:\dev\FlaskTesting ...
Getting scm site credentials for zip deployment
Starting zip deployment. This operation can take a while to complete ...
Deployment endpoint responded with status code 202
You can launch the app at http://XXXXXX-blf.azurewebsites.net
{
  "URL": "http://XXXXXX-blf.azurewebsites.net",
  "appserviceplan": "InsaneSpeech_asp_Linux_westeurope_0",
  "location": "westeurope",
  "name": "XXXXXX-blf",
  "os": "Linux",
  "resourcegroup": "InsaneSpeech_rg_Linux_westeurope",
  "runtime_version": "python|3.7",
  "runtime_version_detected": "-",
  "src_path": "D:\\dev\\FlaskTesting"
}

Then I go to the azure portal and try to change the Stack settings to target Python 3.8 under XXXXXX-blf -> Settings -> Configuration -> General settings -> Stack | Major version / Minor version After clicking save I try to run again the command to update my code

az webapp up -n python-blf

But this time the output shows an error:

Webapp XXXXXX-blf already exists. The command will deploy contents to the existing app.
Updating runtime version from PYTHON|3.8 to python|3.7
Creating zip with contents of dir D:\dev\FlaskTesting ...
Getting scm site credentials for zip deployment
Starting zip deployment. This operation can take a while to complete ...
Deployment endpoint responded with status code 202
Configuring default logging for the app, if not already enabled
Zip deployment failed. {'id': 'd9ff6c84c00844bf9f988bd4c98c81d6', 'status': 3, 'status_text': '', 
'author_email': 'N/A', 'author': 'N/A', 'deployer': 'Push-Deployer', 'message': 'Created via a push deployment', 
'progress': '', 'received_time': '2020-07-05T09:10:02.1802651Z', 'start_time': '2020-07-05T09:10:02.3953194Z', 
'end_time': '2020-07-05T09:10:18.7991349Z', 
'last_success_end_time': None, 'complete': True, 'active': False, 'is_temp': False, 'is_readonly': True, 
'url': 'https://XXXXXX-blf.scm.azurewebsites.net/api/deployments/latest', 
'log_url': 'https://XXXXXX-blf.scm.azurewebsites.net/api/deployments/latest/log', 'site_name': 'XXXXXX-blf'}. 
Please run the command az webapp log deployment show
                           -n XXXXXX-blf -g InsaneSpeech_rg_Linux_westeurope

I check the log url and this is the issue:

{
   "ClassName":"System.IO.FileNotFoundException",
   "Message":"No log found for 'latest'.",
   "Data":null,
   "InnerException":null,
   "HelpURL":null,
   "StackTraceString":"   at Kudu.Core.Deployment.DeploymentManager.GetLogEntries(String id) in /tmp/KuduLite/Kudu.Core/Deployment/DeploymentManager.cs:line 111\n   at Kudu.Services.Deployment.DeploymentController.GetLogEntry(String id) in /tmp/KuduLite/Kudu.Services/Deployment/DeploymentController.cs:line 432",
   "RemoteStackTraceString":null,
   "RemoteStackIndex":0,
   "ExceptionMethod":null,
   "HResult":-2147024894,
   "Source":"Kudu.Core",
   "WatsonBuckets":null,
   "FileNotFound_FileName":null,
   "FileNotFound_FusionLog":null
}

After this issue, without changing anything I can run the same command again and get a correct deployment but with python|3.7 ...

(venv) D:\dev\FlaskTesting [master ≡ +5 ~0 -1 !]> az webapp up -n XXXXXX-blf
Webapp XXXXXX-blf already exists. The command will deploy contents to the existing app.
Creating zip with contents of dir D:\dev\FlaskTesting ...
Getting scm site credentials for zip deployment
Starting zip deployment. This operation can take a while to complete ...
Deployment endpoint responded with status code 202
You can launch the app at http://XXXXXX-blf.azurewebsites.net
{
  "URL": "http://XXXXXX-blf.azurewebsites.net",
  "appserviceplan": "InsaneSpeech_asp_Linux_westeurope_0",
  "location": "westeurope",
  "name": "XXXXXX-blf",
  "os": "Linux",
  "resourcegroup": "InsaneSpeech_rg_Linux_westeurope",
  "runtime_version": "python|3.7",
  "runtime_version_detected": "-",
  "sku": "FREE",
  "src_path": "D:\\dev\\FlaskTesting"
}

UPDATE

I have configured the CI\CD in azure linked to my github repository and the github actions do deploy on push with my webapp running python 3.8

# Docs for the Azure Web Apps Deploy action: https://github.com/Azure/webapps-deploy
# More GitHub Actions for Azure: https://github.com/Azure/actions

name: Build and deploy Python app to Azure Web App - XXXXXX-blf

on:
  push:
    branches:
      - master

jobs:
  build-and-deploy:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@master

    - name: Set up Python version
      uses: actions/setup-python@v1
      with:
        python-version: '3.8'

    - name: Build using AppService-Build
      uses: azure/appservice-build@v1
      with:
        platform: python
        platform-version: '3.8'

    - name: 'Deploy to Azure Web App'
      uses: azure/webapps-deploy@v1
      with:
        app-name: 'XXXXXX-blf'
        slot-name: 'production'
        publish-profile: ${{ XXXXXXXXXXXXXXXXXXX }}

Any idea?

Answer 1

After your description and the tutorial provided, I also found this problem. And in the official documentation, the parameters of the az webapp up command do not support the specified python version.

If you must use the az webapp up command, it should not be possible at present. I think this is a bug, you can raise a support ticket on the portal to confirm.

I give an alternative solution, you can use continuous deployment. You can use git. If the code is confidential, you can also use your own to create a git storage service locally and use local git for deployment. In this case, the application will be automatically deployed after each modification is submitted.