Hi all; I have a Blazor Interactive Server app and have set up health checks as follows: builder.Services.AddHealthChecks() .AddDbContextCheck<TrackingDbContext>("App Database") .AddDbContextCheck<UserDbContext>("Identity Database"); app.MapHealthChecks("health", new HealthCheckOptions { ResponseWriter = UIResponseWriter.WriteHealthCheckUIResponse }).AllowAnonymous(); When I run on my system using the Visual Studio integrated app server, https://localhost:7229/health gives me JSON output with the status of each check. When I run on this same app on Azure App Server using https://ohana.tradewindsstudios.us/health I get: Error. An error occurred while processing your request. Request ID: 00-f4dd263c9fd8791cf7c9dda48954031a-09ba2674b6a1313b-00 Where do I find details on this error? Is there something I need to set in App Server to allow this to work? thanks - dave

Blazor HealthChecks - works on my system, error on Azure App Server

Accepted answer

ajkuma 24,561 Microsoft Employee

Apologies for the delayed response from over the weekend. To fetch more details, you may view the Application event Logs, checkout this doc for more details: #application-event-log-azure-app-service
Based on my understanding of your issue, just to highlight, hosting a Blazor Web App that uses interactive server-side rendering on Azure App Service requires configuration for Application Request Routing (ARR) affinity and WebSockets. The App Service should also be appropriately globally distributed to reduce UI latency.

It is recommend using WebSockets for server-side Blazor apps deployed to Azure App Service. Host and deploy server-side Blazor apps

Also, I see that you have posted it on SO and your previous discussion on this topic.

Ref: Monitor App Service instances using Health check

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David Thielen 2,706

@ajkuma - thanks, this makes some progress.

First off, I do have it set to use web sockets and have ARR on.

I looked at the event log and found:

Category: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware
EventId: 1
SpanId: decddf3ae5a2756d
TraceId: 555615d76022bce06b51fc3b8eab4ff8
ParentId: 0000000000000000
RequestId: 40000085-0000-f700-b63f-84710c7967bb
RequestPath: /health

An unhandled exception has occurred while executing the request.

Exception: 
System.FormatException: No valid combination of account information found.
   at Azure.Storage.StorageConnectionString.<>c.<Parse>b__67_0(String err)
   at Azure.Storage.StorageConnectionString.ParseCore(String connectionString, StorageConnectionString& accountInformation, Action`1 error)
   at Azure.Storage.StorageConnectionString.Parse(String connectionString)
   at Azure.Storage.Blobs.BlobServiceClient..ctor(String connectionString, BlobClientOptions options)
   at HealthChecks.AzureStorage.AzureBlobStorageHealthCheck.<>c__DisplayClass2_0.<.ctor>b__0(String k) in /_/src/HealthChecks.AzureStorage/AzureBlobStorageHealthCheck.cs:line 14
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at ClientCache.GetOrAdd[T](String key, Func`2 clientFactory) in /_/src/ClientCache.cs:line 5
   at HealthChecks.AzureStorage.AzureBlobStorageHealthCheck..ctor(String connectionString, String containerName, BlobClientOptions clientOptions) in /_/src/HealthChecks.AzureStorage/AzureBlobStorageHealthCheck.cs:line 13
   at Microsoft.Extensions.DependencyInjection.AzureStorageHealthCheckBuilderExtensions.<>c__DisplayClass3_0.<AddAzureBlobStorage>b__0(IServiceProvider sp) in /_/src/HealthChecks.AzureStorage/DependencyInjection/AzureStorageHealthCheckBuilderExtensions.cs:line 47
   at Microsoft.Extensions.Diagnostics.HealthChecks.DefaultHealthCheckService.RunCheckAsync(HealthCheckRegistration registration, CancellationToken cancellationToken)
   at Microsoft.Extensions.Diagnostics.HealthChecks.DefaultHealthCheckService.RunCheckAsync(HealthCheckRegistration registration, CancellationToken cancellationToken)
   at Microsoft.Extensions.Diagnostics.HealthChecks.DefaultHealthCheckService.CheckHealthAsync(Func`2 predicate, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckMiddleware.InvokeAsync(HttpContext httpContext)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Localization.RequestLocalizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.StatusCodePagesMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddlewareImpl.<Invoke>g__Awaited|10_0(ExceptionHandlerMiddlewareImpl middleware, HttpContext context, Task task)

That gave me the issue - I had a problem in the BLOB storage connection string. Thank You!

I do have a follow-up question. In that case, shouldn't all the other checks still run?

thanks - dave

ajkuma 24,561 Reputation points Microsoft Employee

2024-07-09T03:43:42.2433333+00:00

I’m glad you found the solution to your specific issue. Thanks for the follow-up and updating the summary of my answer on your SO thread.

As you had a typo in my Azure Storage connection string, the entire health check may had failed.

Regarding reading the event log on your SO, that’s an excellent point! Checking logs, especially when dealing with exceptions or unexpected behavior, is crucial for diagnosing problems.

Much appreciate your feedback.

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Blazor HealthChecks - works on my system, error on Azure App Server

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