AspNetCore.HealthCheck in Azure function always returns 200 even when unhealthy

Question

AspNetCore.HealthCheck in Azure function always returns 200 even when unhealthy

Miss Amber in Seattle 21

We have an Azure Function using .Net Core 7 that we've added a HealthCheck to. The healthcheck fires, if the status is set to unhealthy, we return a an instance of ServiceUnavailableObjectResult. The HTTP status code always returns 200 regardless of what we return.

From Program.cs

services.AddHealthChecks()
    .AddUrlGroup(
        uri: new Uri($"{baseAddress}/health"),
        name: "Mgmt")
    .AddAzureBlobStorage(
        connectionString: context.Configuration.GetValue<string>(RecipientUploadOptions.BlobConnectionStringName),
        containerName: context.Configuration.GetValue<string>(RecipientUploadOptions.IncomingContainerName),
        name: "IncomingBlobContainer")
    .AddAzureBlobStorage(
        connectionString: context.Configuration.GetValue<string>(RecipientUploadOptions.BlobConnectionStringName),
        containerName: context.Configuration.GetValue<string>(RecipientUploadOptions.ErrorContainerName),
        name: "ErrorBlobContainer")
    .AddAzureBlobStorage(
        connectionString: context.Configuration.GetValue<string>(RecipientUploadOptions.BlobConnectionStringName),
        containerName: context.Configuration.GetValue<string>(RecipientUploadOptions.ArchiveContainerName),
        name: "ArchiveBlobContainer");

From HealthCheckFunction.cs

Function("health")]
public async Task<IActionResult> Health([HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequestData z)
{
    var status = await _healthCheckService.CheckHealthAsync();
    if (status.Status == HealthStatus.Healthy)
    {
        return new OkObjectResult(Enum.GetName(typeof(HealthStatus), status.Status));
    }

    return new ServiceUnavailableObjectResult(Enum.GetName(typeof(HealthStatus), status.Status));
}

Expected:

The HTTP status code returned is 503 - Service Unavailable along with the payload.

Actual:

The HTTP status code returned os 200 - OK along with the payload
The same code used for HealthChecks in web API projects return 503 as expected

ScreenCap

Any suggestions would be greatly appreciated.

Pramod Valavala 20,661 Reputation points Microsoft Employee Moderator

2023-07-12T14:37:15.0833333+00:00

@Miss Amber in Seattle Since you are using .NET 7 (and hence isolated workers) with ASP.NET types, you need perform a few steps as mentioned in the docs. Could you confirm if you have followed these?
Miss Amber in Seattle 21 Reputation points

2023-07-12T16:24:12.6433333+00:00

@Pramod Valavala Those instructions to do not appear to be accurate. Browsing in the NuGet Package Manager UI for "Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" returns "No packages found".

Edit: It helps if I have "Include pre-release" checked.

However, following those instructions causes the request to the health check to never complete.
Miss Amber in Seattle 21 Reputation points

2023-07-12T16:27:30.67+00:00

[ Deleted duplicate ]
Pramod Valavala 20,661 Reputation points Microsoft Employee Moderator

2023-07-13T21:53:10.8566667+00:00

@Miss Amber in Seattle I've tested the steps for using ASP.NET types and can confirm it works.

I believe you might have missed the last step from the docs which was to set the AzureWebJobsFeatureFlags app setting value to EnableHttpProxying

Answer accepted by question author

Pramod Valavala 20,661 Microsoft Employee Moderator

@Miss Amber in Seattle There are two ways you can develop HTTP functions when using .NET Isloted Worker.

Built-in HTTP Model

For this you need to return the HttpResponseData type as follows

[Function(nameof(Health))]
public async Task<HttpResponseData> Health([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestData req)
{
    var response = req.CreateResponse();

    var status = await _healthCheckService.CheckHealthAsync();

    await response.WriteAsJsonAsync(
        Enum.GetName(typeof(HealthStatus), status.Status),
        status.Status == HealthStatus.Healthy ? HttpStatusCode.OK : HttpStatusCode.ServiceUnavailable
    );

    return response;
}

ASP.NET Core integration (preview)

There are a few pre-requisites to get this model to work which are documented in the doc linked above. Here are the same for reference.

Install the Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore NuGet package, version 1.0.0-preview2 or later (Note that you must check the include prerelease checkbox in Visual Studio)

Also, make sure Microsoft.Azure.Functions.Worker.Sdk is version 1.11.0 or later and Microsoft.Azure.Functions.Worker is version 1.16.0 or later.

Replace ConfigureFunctionsWorkerDefaults with ConfigureFunctionsWebApplication in Program.cs
Use HttpRequest and IActionResult types from ASP.NET
Add the AzureWebJobsFeatureFlags app setting with value EnableHttpProxying

Pramod Valavala 20,661 Reputation points Microsoft Employee Moderator

2023-07-13T21:02:27.42+00:00

@Miss Amber in Seattle I've got a chance to test this out and updated the code a bit to get this to work as expected. Hope this helps.
Miss Amber in Seattle 21 Reputation points

2023-07-13T21:36:32.0866667+00:00

This doesn't quite give me everything I need but it gives me a working starting point.

Thank you!

1 additional answer

Your answer

Pramod Valavala 20,661 Reputation points Microsoft Employee Moderator

2023-07-12T14:37:15.0833333+00:00

@Miss Amber in Seattle Since you are using .NET 7 (and hence isolated workers) with ASP.NET types, you need perform a few steps as mentioned in the docs. Could you confirm if you have followed these?
Miss Amber in Seattle 21 Reputation points

2023-07-12T16:24:12.6433333+00:00

@Pramod Valavala Those instructions to do not appear to be accurate. Browsing in the NuGet Package Manager UI for "Microsoft.Azure.Functions.Worker.Extensions.Http.AspNetCore" returns "No packages found".

Edit: It helps if I have "Include pre-release" checked.

However, following those instructions causes the request to the health check to never complete.
Miss Amber in Seattle 21 Reputation points

2023-07-12T16:27:30.67+00:00

[ Deleted duplicate ]
Pramod Valavala 20,661 Reputation points Microsoft Employee Moderator

2023-07-13T21:53:10.8566667+00:00

@Miss Amber in Seattle I've tested the steps for using ASP.NET types and can confirm it works.

I believe you might have missed the last step from the docs which was to set the AzureWebJobsFeatureFlags app setting value to EnableHttpProxying
Pramod Valavala 20,661 Reputation points Microsoft Employee Moderator

2023-07-13T21:02:27.42+00:00

@Miss Amber in Seattle I've got a chance to test this out and updated the code a bit to get this to work as expected. Hope this helps.
Miss Amber in Seattle 21 Reputation points

2023-07-13T21:36:32.0866667+00:00

This doesn't quite give me everything I need but it gives me a working starting point.

Thank you!

Answer 1

Based on @Pramod Valavala 's code above, here is my implementation.

 [Function(nameof(Health))]
    public async Task<HttpResponseData> Health([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestData req)
    {
        var response = req.CreateResponse();
        var status = await _healthCheckService.CheckHealthAsync();

        var httpStatus = (status.Status == HealthStatus.Healthy
            ? HttpStatusCode.OK
            : HttpStatusCode.ServiceUnavailable);

        var statusResult = new
        {
            Value = Enum.GetName(typeof(HealthStatus), status.Status),
            Formatters = new string[] { },
            ContentType = "application/json",
            StatusCode = httpStatus
        };

        await response.WriteAsJsonAsync(statusResult, httpStatus);

        return response;
    }

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AspNetCore.HealthCheck in Azure function always returns 200 even when unhealthy

Built-in HTTP Model

ASP.NET Core integration (preview)

1 additional answer

Your answer