Python Web app not running on Azure App Service

Question

Hello All,

Its been a while since I created a classic release pipeline for deployment to app serivce. I followed the below guide to create only the build pipeline but created a classic release pipeline for deployment.

https://learn.microsoft.com/en-us/azure/devops/pipelines/ecosystems/python-webapp?view=azure-devops

The build is running fine and generating the artifact, and I am able to use the artifact in my release pipeline. In release pipeline I am using "Azure App Service deploy" to deploy to the app service. The release pipeline deploys successfully but on the webapp I see the default page and not the page that is from the code. So I did a bit of troubleshooting and find out that in the wwwroot folder I have a zip file of the drop and the content of the artifact/zip file has not been extracted. I think this is the problem but not sure how to fix it.

Appreciate any help.

Sid

Answer 1

I have added the Application setting SCM_DO_BUILD_DURING_DEPLOYMENT and set it to true. It has extracted the artifact but the app is still showing the default Microsoft page. But what I think the problem now is that the artifact contains a folder named "s" and inside s all the contents of the app are. so inside wwwroot folder I have s and inside s I have the applicaiton. I dont know If this is the problem and what to do in the build pipeline to remove the s directory.

Answer 2

The behavior matches a deployment package being copied but not built into a runnable Python app on App Service. For Python on Linux App Service, if the app shows the default page after a successful deployment, App Service either didn’t find the app files under site/wwwroot or didn’t build the app during deployment.

Use this troubleshooting path:

1. In Azure Portal, open the web app and restart it.
   • Wait about 20 seconds and test again.
2. Verify what exists under site/wwwroot.
   • If only the artifact zip is present and the app files are not expanded there, App Service is not seeing a deployed runnable app layout.
3. Enable build during deployment.
   • In the web app, go to Configuration.
   • On Application Settings, add:
     • Name: SCM_DO_BUILD_DURING_DEPLOYMENT
     • Value: true
   • Save the setting.
   • Redeploy or run the pipeline again.
4. Check deployment logs and App Service diagnostics.
   • In the Azure portal, open Diagnose and solve problems.
   • Go to Availability and Performance.
   • Review Application Logs, Container Crash, and Container Issues.
   • Also review the deployment logs for errors such as missing requirements.txt or startup detection issues.
5. Confirm the deployment package contains the app in the expected structure.
   • The app code and requirements.txt need to be in the project root that gets deployed.
   • If App Service cannot find the app code, it can fall back to the default page.
6. If the files do exist in site/wwwroot after redeployment but the app still does not start, check startup detection.
   • For Python apps, ensure the app is structured as App Service expects, or use a custom startup command.

Important detail for the pipeline setup:

• The Python web app pipeline guidance notes that missing dependency installation during deployment commonly happens when the web app was created in the portal instead of with az webapp up.
• az webapp up sets SCM_DO_BUILD_DURING_DEPLOYMENT=true; portal-created apps do not set this automatically.

Since the release succeeds but the site shows the default page, the most likely fix is to set SCM_DO_BUILD_DURING_DEPLOYMENT to true and redeploy, then verify that the deployed files appear under site/wwwroot instead of only the zip artifact.

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• Use Azure Pipelines to build and deploy a Python web app to Azure App Service
• Configure a Linux Python app for Azure App Service
• Troubleshoot Azure Web App deployment tasks