Description
Describe the bug
When I add or remove a custom domain programmatically using the Microsoft.Azure.Management.AppService.Fluent nuget package, the app service restarts. I have confirmed that the app is indeed restarting by creating an empty aspnet core app and only enabling Serilog logging to log when Program.Main(), Startup.ConfigureServices() and Startup.Configure() methods are executed. I found this related issue (MicrosoftDocs/azure-docs#13429) where it is stated by the Microsoft guys that this should not happen.
This is a fragment of my logs after adding or removing a custom domain:
custom hostname added
...
2020-04-06 10:24:47.738 +00:00 [Debug] Hosting shutdown
2020-04-06 10:24:47.766 +00:00 [Debug] Connection id ""0HLUQ2GL99IA2"" disconnecting.
2020-04-06 10:24:47.766 +00:00 [Debug] Connection id ""0HLUQ2GL99IA2"" sending FIN.
2020-04-06 10:24:47.767 +00:00 [Debug] Connection id ""0HLUQ2GL99IA2"" stopped.
2020-04-06 10:24:52.791 +00:00 [Warning] Starting App (Environment: )
2020-04-06 10:24:53.046 +00:00 [Information] Executing Startup.ConfigureServices()
2020-04-06 10:24:53.064 +00:00 [Debug] Hosting starting
2020-04-06 10:24:53.105 +00:00 [Information] Executing Startup.Configure()
2020-04-06 10:24:53.211 +00:00 [Debug] Hosting started
2020-04-06 10:24:53.218 +00:00 [Debug] Loaded hosting startup assembly "TestAppRestart"
2020-04-06 10:24:53.221 +00:00 [Debug] Loaded hosting startup assembly "Microsoft.AspNetCore.Server.IISIntegration"
2020-04-06 10:24:53.439 +00:00 [Debug] Connection id ""0HLUQ2IVF58AG"" started.
2020-04-06 10:24:53.521 +00:00 [Debug] Connection id ""0HLUQ2IVF58AG"" received FIN.
2020-04-06 10:24:53.525 +00:00 [Debug] Connection id ""0HLUQ2IVF58AG"" disconnecting.
2020-04-06 10:24:53.539 +00:00 [Debug] Connection id ""0HLUQ2IVF58AG"" sending FIN.
2020-04-06 10:24:53.542 +00:00 [Debug] Connection id ""0HLUQ2IVF58AH"" started.
2020-04-06 10:24:53.559 +00:00 [Debug] Connection id ""0HLUQ2IVF58AG"" stopped.
...
custom hostname removed
...
2020-04-06 10:26:57.775 +00:00 [Debug] Hosting shutdown
2020-04-06 10:26:57.805 +00:00 [Debug] Connection id ""0HLUQ2IVF58AI"" disconnecting.
2020-04-06 10:26:57.805 +00:00 [Debug] Connection id ""0HLUQ2IVF58AI"" sending FIN.
2020-04-06 10:26:57.806 +00:00 [Debug] Connection id ""0HLUQ2IVF58AI"" stopped.
2020-04-06 10:27:03.285 +00:00 [Warning] Starting App (Environment: )
2020-04-06 10:27:03.540 +00:00 [Information] Executing Startup.ConfigureServices()
2020-04-06 10:27:03.559 +00:00 [Debug] Hosting starting
2020-04-06 10:27:03.606 +00:00 [Information] Executing Startup.Configure()
2020-04-06 10:27:03.787 +00:00 [Debug] Hosting started
2020-04-06 10:27:03.794 +00:00 [Debug] Loaded hosting startup assembly "TestAppRestart"
2020-04-06 10:27:03.795 +00:00 [Debug] Loaded hosting startup assembly "Microsoft.AspNetCore.Server.IISIntegration"
2020-04-06 10:27:04.098 +00:00 [Debug] Connection id ""0HLUQ2K6D7LQ0"" started.
2020-04-06 10:27:04.178 +00:00 [Debug] Connection id ""0HLUQ2K6D7LQ0"" received FIN.
2020-04-06 10:27:04.191 +00:00 [Debug] Connection id ""0HLUQ2K6D7LQ0"" disconnecting.
2020-04-06 10:27:04.219 +00:00 [Debug] Connection id ""0HLUQ2K6D7LQ0"" sending FIN.
2020-04-06 10:27:04.238 +00:00 [Debug] Connection id ""0HLUQ2K6D7LQ0"" stopped.
2020-04-06 10:27:04.301 +00:00 [Debug] Connection id ""0HLUQ2K6D7LQ1"" started.
...
I've created another issue for the Azure Documentation guys here MicrosoftDocs/azure-docs#51741 (comment) bucause adding/removing custom domains on the Azure portal is causing the exact same behavior. The app stays unresponsive for almost a minute for all other domains bound to it and for the default domain assigned by Azure. I might be wrong but I guess the two issues boil down to the same core problem.
I've tested with both netcore 2.1 and 3.1. I also checked the eventlog.xml file on my app service storage using the kudu console and I can see the shutdown and startup events firing.
Could you please tell me if this is by design or is it an Azure problem or I'm missing/misinterpreting something? Is there anything I could do to avoid the restart of the app service?
To Reproduce
- Create a new aspnet core app, enable logging and log when
Program.Main(),Startup.Configure()andStartup.ConfigureServices()are called. - Deploy to a new Azure App Service.
- Programmatically add/remove a custom hostname.
- Check logs or
eventlog.xmlfile and look forshutdown.
Code Snippet
This is the code I'm using to add a custom hostname
await webApp.Update()
.DefineHostnameBinding()
.WithThirdPartyDomain("test.example.com")
.WithSubDomain("test.example.com")
.WithDnsRecordType(CustomHostNameDnsRecordType.CName)
.Attach()
.ApplyAsync();... and to delete it
await webApp
.Update()
.WithoutHostnameBinding("test.example.com")
.ApplyAsync();Expected behavior
After adding / removing custom hostname, the app service should not restart. If this is by design, the documentation should be clear about it.
Setup (please complete the following information):
- OS: Azure (Windows App Service Plan)
- Version of the Library used: Both 1.13.0 and 1.32.0
Information Checklist
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