Azure Devops: Pipeline fails to deploy to Linux Web App - azure-devops

Question

I have a pipeline deploying to my Azure web app, that most of the times errors out because it couldn't deploy to my web app. The task take around 25 mins :
...
Copying file: 'frontend/.gitignore'
Copying file: 'frontend/README.md'
Copying file: 'frontend/package.json'
Copying file: 'frontend/tsconfig.json'
Copying file: 'frontend/yarn.lock'
Omitting next output lines...
An error has occurred during web site deployment.
Kudu Sync failed
\n/opt/Kudu/Scripts/starter.sh "/home/site/deployments/tools/deploy.sh"
##[error]Failed to deploy web package to App Service.
##[error]To debug further please check Kudu stack trace URL : https://$someapp:***#someapp.scm.azurewebsites.net/api/vfs/LogFiles/kudu/trace
##[error]Error: Package deployment using ZIP Deploy failed. Refer logs for more details.
...
When i enable : system.debug = true , i see these logs repeated many time , before start copying the artifact files :
POLL URL RESULT: {"statusCode":202,"statusMessage":"Accepted","headers":{"transfer-encoding":"chunked","content-type":"application/json; charset=utf-8","location":"http://XXXXXXXXX.scm.azurewebsites.net:80/api/deployments/latest?deployer=VSTS_ZIP_DEPLOY&time=2021-07-09_09-01-41Z","server":"Kestrel","date":"Fri, 09 Jul 2021 09:23:37 GMT","connection":"close"},"body":{"id":"68a7a8811796416b993924437493ff87","status":0,"status_text":"Building and Deploying '68a7a8811796416b993924437493ff87'.","author_email":"N/A","author":"N/A","deployer":"VSTS_ZIP_DEPLOY","message":"Created via a push deployment","progress":"Running deployment command...","received_time":"2021-07-09T09:01:50.4159225Z","start_time":"2021-07-09T09:01:51.775357Z","end_time":null,"last_success_end_time":null,"complete":false,"active":false,"is_temp":false,"is_readonly":true,"url":null,"log_url":null,"site_name":"XXXXXXXXXXXXe"}}
Deployment status: 0 'Building and Deploying '68a7a8811796416b993924437493ff87'.'. retry after 5 seconds
setting affinity cookie ["ARRAffinity=c06e9bb74f52245b3695b3079a52f6acbc70c3ee812f67e4fa3f5f65088ff4f7;Path=/;HttpOnly;Secure;Domain=XXXXXXXXXXXXXXXXXXXXXXXXXXXXX.scm.azurewebsites.net","ARRAffinitySameSite=c06e9bb74f52245b3695b3079a52f6acbc70c3ee812f67e4fa3f5f65088ff4f7;Path=/;HttpOnly;SameSite=None;Secure;Domain=XXXXXXXXXXXXXXX.scm.azurewebsites.net"]
[GET]https://XXXXXXXXXXX-test.scm.azurewebsites.net:443/api/deployments/latest?deployer=VSTS_ZIP_DEPLOY&time=2021-07-09_09-01-41Z
POLL URL RESULT: {"statusCode":202,"statusMessage":"Accepted","headers":{"transfer-encoding":"chunked","content-type":"application/json; charset=utf-8","location":"http://XXXXXXXXXXXXXXXXXXX.scm.azurewebsites.net:80/api/deployments/latest?deployer=VSTS_ZIP_DEPLOY&time=2021-07-09_09-01-41Z","server":"Kestrel","date":"Fri, 09 Jul 2021 09:23:45 GMT","connection":"close"},"body":{"id":"68a7a8811796416b993924437493ff87","status":0,"status_text":"Building and Deploying '68a7a8811796416b993924437493ff87'.","author_email":"N/A","author":"N/A","deployer":"VSTS_ZIP_DEPLOY","message":"Created via a push deployment","progress":"Running deployment command...","received_time":"2021-07-09T09:01:50.4159225Z","start_time":"2021-07-09T09:01:51.775357Z","end_time":null,"last_success_end_time":null,"complete":false,"active":false,"is_temp":false,"is_readonly":true,"url":null,"log_url":null,"site_name":"XXXXXXXXXXXX"}}
Deployment status: 0 'Building and Deploying '68a7a8811796416b993924437493ff87'.'. retry after 5 seconds
setting affinity cookie ["ARRAffinity=c06e9bb74f52245b3695b3079a52f6acbc70c3ee812f67e4fa3f5f65088ff4f7;Path=/;HttpOnly;Secure;Domain=XXXXXXXXXXXXXXXXXXXXXX.scm.azurewebsites.net","ARRAffinitySameSite=c06e9bb74f52245b3695b3079a52f6acbc70c3ee812f67e4fa3f5f65088ff4f7;Path=/;HttpOnly;SameSite=None;Secure;Domain=XXXXXXXXXXXXXXXXXX"]
This task fails only in specific slot in myweb app , authors slots and production slot works fine and the job take around 6 mins
Any ideas what could be wrong?

Answer 1

As per the discussion and troubleshooting performed here, I tried to setup a Linux App Service on Standard S1 pricing tier enabling 5 (max) slots with CI/CD configured via Azure Pipelines. Unfortunately, I wasn't able to reproduce the same error as yours despite multiple different trials.
I'd suggest you to try the following:
Kudu Sync failed in the deployment log resembles this open issue from about a year ago: ZipDelpoy on azure web app linux fails during kudu sync #2972. Please check the trace/deployment log files on kudu at https://<appname>.scm.azurewebsites.net/api/vfs/LogFiles/kudu/trace or /deployment or from Kudu's DebugConsole (/LogFiles/kudu/\*) and check if this is caused by deployment lock failures. In that case, check this wiki out for dealing with locked files during deployment.
Try a different deployment method like run from package (to avoid resource locking), using FTP/S, or local git deployment.
This should help you narrow down the issue further, whether it is caused in the App service/deployment method, or the ADO pipeline/task.
Scale up to the next higher tier and re-trigger your pipeline. If it succeeds, you may scale back down to the original tier. This would indirectly restart your SCM sites as well.
If the above workarounds don't help, you could check on the following:
Customize your deploy task with options like TakeAppOfflineFlag, DeploymentType or RenameFilesFlag to streamline your deployment.
Try restarting the app/slot just before the deployment in order to recycle the app pool.
Check if your app is running into any of the prescribed limits (ex: file system storage) for your tier.
Drill down into available metrics for your app to identify any CPU/Memory anomalies.
Try the Diagnose and solve problems tool for any additional insights about your app.
If your environment permits, try setting up and deploying to a new slot within your App Service, or try verifying if this happens to another app in a different region.