Retrofitting Azure SignalR to Existing App Service

[darena-patrick]

Describe the bug

• ✅ When publishing / deploying via Visual Studio Web Deploy, connecting the Azure SignalR Service Dependency works as expected.
• ❌ When publishing / deploying via the dotnet publish command (via GitHub Actions CI/CD), the SignalR service does not properly connect to the app service.

To Reproduce

• Create a sample Blazor project that leverages SignalR
• Publish to Azure App Service via Visual Studio and create Service Dependency on an Azure SignalR service via the UI
  
• Without making any changes to the infrastructure, deploy via dotnet commandline and deploy to Azure App Service.
• Errors will appear such as these:
  
  

Further technical details

• Your Azure SignalR SDK version:
  <PackageReference Include="Microsoft.Azure.SignalR" Version="1.18.3" />

In the appsettings.json file:

"Azure": {
    "SignalR": {
      "Enabled": "true",
      "ConnectionString": "redacted"
    }
  }

Is there something extra that is needed besides adding the package reference to the project and adding the settings to appsettings.json that need to be done to accomplish this?

[darena-patrick]

I did two apps side by side ... exact same binaries / configuration. In Kudu in Azure I ran the application via Debug Console.... here is the difference between the outputs:

The one published via Visual Studio:

info: Microsoft.Azure.SignalR.Connections.Client.Internal.WebSocketsTransport[1]
      Starting transport. Transfer mode: Binary. Url: 'wss://signalr-REDACTED.service.signalr.net/server/?hub=componenthub&cid=REDACTED'.
info: Microsoft.Azure.SignalR.Connections.Client.Internal.WebSocketsTransport[1]
      Starting transport. Transfer mode: Binary. Url: 'wss://signalr-REDACTED.service.signalr.net/server/?hub=componenthub&cid=REDACTED'.
info: Microsoft.Azure.SignalR.Connections.Client.Internal.WebSocketsTransport[1]
      Starting transport. Transfer mode: Binary. Url: 'wss://signalr-REDACTED.service.signalr.net/server/?hub=componenthub&cid=REDACTED'.
info: Microsoft.Azure.SignalR.Connections.Client.Internal.WebSocketsTransport[1]
      Starting transport. Transfer mode: Binary. Url: 'wss://signalr-REDACTED.service.signalr.net/server/?hub=componenthub&cid=REDACTED'.
info: Microsoft.Azure.SignalR.Connections.Client.Internal.WebSocketsTransport[1]
      Starting transport. Transfer mode: Binary. Url: 'wss://signalr-REDACTED.service.signalr.net/server/?hub=componenthub&cid=REDACTED'.
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Production
info: Microsoft.Hosting.Lifetime[0]
      Content root path: C:\home\site\wwwroot\
info: Microsoft.Azure.SignalR.StrongServiceConnectionContainer[1]
      Hub 'ComponentHub' is now connected to '(Primary)https://signalr-REDACTED.service.signalr.net(hub=ComponentHub)'.

The one published with dotnet publish

info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Production
info: Microsoft.Hosting.Lifetime[0]
      Content root path: C:\home\site\wwwroot\

[darena-patrick]

I did some detailed comparison of the side-by-side and found the only difference was that the Visual Studio version has an entry in web.config that was not in dotnet publish:

<environmentVariables>
  <environmentVariable name="ASPNETCORE_HOSTINGSTARTUPASSEMBLIES" value="Microsoft.Azure.SignalR"/>
</environmentVariables>

The ridiculous thing is ... I also have this exact same variable in both application's Azure configuration:

So the question I have is ... why does it only work if it's manually in the web.config and not in the app service settings?

[Y-Sindo]

About the question why "ASPNETCORE_HOSTINGSTARTUPASSEMBLIES" environment variable doesn't work in App Service settings, App Service support is probably a better channel to go through.

[Swellenator]

I have this issue also. I have set these configuration values:

Yet it uses regular SignalR and not Azure SignalR.

[vicancy]

Hi @davidfowl / @BrennanConroy do you know who we can contact to update the dotnet publish behavior?

[BrennanConroy]

Do you have the ASP.NET Core Logging Integration site extension installed in your azure app service app? There is an old bug where it overwrites a couple environment variables (like ASPNETCORE_HOSTINGSTARTUPASSEMBLIES), so when you remove the extension that environment variable will start working.
dotnet/aspnetcore#4136