Dash/Flask Python App Azure Deployment: Application object must be callable

Question

so I'm trying to deploy my Dash app onto Azure using Azure Web App. When I use the "Github Actions" method of deployment, I get the following (I even made my repository public for this):

Package deployment using ZIP Deploy initiated.
##[error]Failed to deploy web package to App Service.
##[error]Deployment Failed with Error: Error: Failed to deploy web package to App Service.
Unauthorized (CODE: 401)
##[warning]Error: Failed to update deployment history.
Unauthorized (CODE: 401)
App Service Application URL: http://my-site.azurewebsites.net

I've also tried deploying with "Kudu App Build" instead of the Github Actions and that "deploys successfully", giving me a status of "Success(Active)" but once I go to my website it fails, then when I go to Diagnosis and solve problems in the azure portal I receive the following error:

2020-06-05T14:32:08.567155259Z 
2020-06-05T14:32:08.567159059Z Documentation: http://aka.ms/webapp-linux
2020-06-05T14:32:08.567163159Z Python 3.8.0
2020-06-05T14:32:08.567166959Z Note: Any data outside '/home' is not persisted
2020-06-05T14:32:09.126144120Z Starting OpenBSD Secure Shell server: sshd.
2020-06-05T14:32:09.177989757Z Site's appCommandLine: gunicorn --bind=0.0.0.0 --timeout 600 application:app
2020-06-05T14:32:09.179066899Z Launching oryx with: -appPath /home/site/wwwroot -output /opt/startup/startup.sh -virtualEnvName antenv -defaultApp /opt/defaultsite -userStartupCommand 'gunicorn --bind=0.0.0.0 --timeout 600 application:app'
2020-06-05T14:32:09.289253728Z Oryx Version: 0.2.20200114.13, Commit: 204922f30f8e8d41f5241b8c218425ef89106d1d, ReleaseTagName: 20200114.13
2020-06-05T14:32:09.315423056Z Found build manifest file at '/home/site/wwwroot/oryx-manifest.toml'. Deserializing it...
2020-06-05T14:32:09.322220623Z Build Operation ID: |mqhAw8K+i4s=.a5925a0c_
2020-06-05T14:32:09.937709104Z Writing output script to '/opt/startup/startup.sh'
2020-06-05T14:32:10.656204831Z Found virtual environment .tar.gz archive.
2020-06-05T14:32:10.656991662Z Removing existing virtual environment directory /antenv...
2020-06-05T14:32:10.667494675Z Extracting to directory /antenv...
2020-06-05T14:32:42.888599159Z Using packages from virtual environment antenv located at /antenv.
2020-06-05T14:32:42.891102058Z Updated PYTHONPATH to ':/antenv/lib/python3.8/site-packages'
2020-06-05T14:32:44.966320399Z [2020-06-05 14:32:44 +0000] [42] [INFO] Starting gunicorn 20.0.4
2020-06-05T14:32:44.973255871Z [2020-06-05 14:32:44 +0000] [42] [INFO] Listening at: http://0.0.0.0:8000 (42)
2020-06-05T14:32:44.974184808Z [2020-06-05 14:32:44 +0000] [42] [INFO] Using worker: sync
2020-06-05T14:32:45.047728498Z [2020-06-05 14:32:45 +0000] [44] [INFO] Booting worker with pid: 44
2020-06-05T14:32:50.315649084Z Application object must be callable.
2020-06-05T14:32:50.321677821Z [2020-06-05 14:32:50 +0000] [44] [INFO] Worker exiting (pid: 44)
2020-06-05T14:32:50.630621560Z [2020-06-05 14:32:50 +0000] [42] [INFO] Shutting down: Master
2020-06-05T14:32:50.630656561Z [2020-06-05 14:32:50 +0000] [42] [INFO] Reason: App failed to load.

That was the application error, here is the container error

Please use https://aka.ms/linux-diagnostics to enable logging to see container logs here.
2020-06-05T14:30:22.831Z INFO  - Initiating warmup request to container my-site_0_06a70784 for site my-site
2020-06-05T14:30:38.890Z INFO  - Waiting for response to warmup request for container my-site_0_06a70784. Elapsed time = 16.0594968 sec
2020-06-05T14:30:54.492Z INFO  - Waiting for response to warmup request for container my-site_0_06a70784. Elapsed time = 31.6616936 sec
2020-06-05T14:31:09.663Z ERROR - Container my-site_0_06a70784 for site my-site has exited, failing site start
2020-06-05T14:31:09.695Z ERROR - Container my-site_0_06a70784 didn't respond to HTTP pings on port: 8000, failing site start. See container logs for debugging.
2020-06-05T14:31:10.217Z INFO  - Stopping site my-site because it failed during startup.
2020-06-05T14:31:11.646Z INFO  - Starting container for site
2020-06-05T14:31:11.647Z INFO  - docker run -d -p 4040:8000 --name my-site_0_9c00d1f9 -e WEBSITE_SITE_NAME=my-site -e WEBSITE_AUTH_ENABLED=False -e WEBSITE_ROLE_INSTANCE_ID=0 -e WEBSITE_HOSTNAME=my-site.azurewebsites.net -e WEBSITE_INSTANCE_ID=b78e390e9ef390f579e4e316c4d4ea6c7f187e4af48b856ebd3562fda3c5ef4f appsvc/python:3.8_20200101.1 gunicorn --bind=0.0.0.0 --timeout 600 application:app 

Here is what my application.py looks like (I've tried several variations of this to no avail):

 import app as application
 app = application.app

 if __name__ == "__main__":
     app.run_server(debug=False)

And at the top of my app.py file I have:

 app = dash.Dash(__name__)

This is my requirements.txt:

 bs4==0.0.1
 dash==1.12.0
 dash-table==4.7.0
 Flask==1.1.2
 numpy==1.18.0
 pandas==1.0.4
 requests==2.12.4

Lastly, this is the startup command I use in the Configuration->General Settings->Startup Command

 gunicorn --bind=0.0.0.0 --timeout 600 application:app

Answer 1

The application you should run when deployment is dash.Dash.server(in your case it's app.server), it's the underly Flask application. So, you have to update the second line of your application.py to this:

app = application.server

See more in Dash docs.