C#•2y ago

❔ IHealthCheck and Swagger

Hello. I'm experimenting with the interface IHealthCheck in my Web Service. I used to have a endpoint that would just return 200OK called /health, but I discovered that there was a Interface for this, and with many functionalities, so I want to try get it working. I followed the documentation (https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/health-checks?view=aspnetcore-7.0) and it kinda works, except Swagger complains a lot. This is what my Controller looks like (the health check part):

[Route("api/[controller]")]
[ApiController]
public class PostalController : ControllerBase, IHealthCheck
{
  //...
  public Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
  {
    var isHealthy = true;

    // ...

    if (isHealthy) 
    {
        return Task.FromResult(HealthCheckResult.Healthy());
    }

    return Task.FromResult(
        new HealthCheckResult(context.Registration.FailureStatus));
  }
}

[Route("api/[controller]")]
[ApiController]
public class PostalController : ControllerBase, IHealthCheck
{
  //...
  public Task<HealthCheckResult> CheckHealthAsync(HealthCheckContext context, CancellationToken cancellationToken = default)
  {
    var isHealthy = true;

    // ...

    if (isHealthy) 
    {
        return Task.FromResult(HealthCheckResult.Healthy());
    }

    return Task.FromResult(
        new HealthCheckResult(context.Registration.FailureStatus));
  }
}

In Program.cs I have the following code:

builder.Services.AddHealthChecks().AddCheck<PostalController>("Postal Health Check");

//...
app.MapHealthChecks("/healthz", new Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckOptions 
{ 
    AllowCachingResponses = false,
    ResultStatusCodes =
    {
        [HealthStatus.Healthy] = StatusCodes.Status200OK,
        [HealthStatus.Degraded] = StatusCodes.Status200OK,
        [HealthStatus.Unhealthy] = StatusCodes.Status503ServiceUnavailable
    }
});

builder.Services.AddHealthChecks().AddCheck<PostalController>("Postal Health Check");

//...
app.MapHealthChecks("/healthz", new Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckOptions 
{ 
    AllowCachingResponses = false,
    ResultStatusCodes =
    {
        [HealthStatus.Healthy] = StatusCodes.Status200OK,
        [HealthStatus.Degraded] = StatusCodes.Status200OK,
        [HealthStatus.Unhealthy] = StatusCodes.Status503ServiceUnavailable
    }
});

When I run the program, I get this message from Swagger: (attached image)

11 Replies

júlioOP•2y ago

Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Ambiguous HTTP method for action - Postal.Controllers.PostalController.CheckHealthAsync (Postal). Actions require an explicit HttpMethod binding for Swagger/OpenAPI 3.0
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperations(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePaths(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwaggerDocumentWithoutFilters(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwaggerAsync(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Ambiguous HTTP method for action - Postal.Controllers.PostalController.CheckHealthAsync (Postal). Actions require an explicit HttpMethod binding for Swagger/OpenAPI 3.0
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperations(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePaths(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwaggerDocumentWithoutFilters(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwaggerAsync(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

This is the Log I get. If I add a [HttpGet("/healthz")] to the Health Check in the Controller, Swagger stops complaining but the behaviour of the endpoint is very weird.

júlioOP•2y ago

júlioOP•2y ago

It has this huge JSON that I have no clue what it's doing there.

júlioOP•2y ago

message.txt

júlioOP•2y ago

If I try to access the endpoint manually I get this:

júlioOP•2y ago

Any idea of what is going on?

Tvde1•2y ago

when you do

services.AddSwaggerGen(options =>
{

});

services.AddSwaggerGen(options =>
{

});

(which is responsible for making the json file) it's possible to change a lot by calling methods on the options. You might be able to exclude these endpoints, or add a default "HttpMethod binding" this is the direction I would search in, not sure how to completely fix your issue I think it's complaining that the public method on your controller, does not have a [HttpGet] or post or so you could add a "IActionModelConvention" to the swagger pipeline that looks like:

public class ApiExplorerConvention : IActionModelConvention
{
    public void Apply(ActionModel action)
    {
        action.ApiExplorer.IsVisible = action.Name = "CheckHealthAsync";
    }
}

public class ApiExplorerConvention : IActionModelConvention
{
    public void Apply(ActionModel action)
    {
        action.ApiExplorer.IsVisible = action.Name = "CheckHealthAsync";
    }
}

Not sure if that fixes it (or if the name is a valid property) Taken from https://github.com/domaindrivendev/Swashbuckle.AspNetCore/issues/2031#issuecomment-785384452

júlioOP•2y ago

I took your direction and found this https://stackoverflow.com/questions/29701573/how-to-omit-methods-from-swagger-documentation-on-webapi-using-swashbuckle

Stack Overflow

How to omit methods from Swagger documentation on WebAPI using Swas...

I have a C# ASP.NET WebAPI application with API documentation being automatically generated using Swashbuckle. I want to be able to omit certain methods from the documentation but I can't seem to ...

júlioOP•2y ago

I can add [ApiExplorerSettings(IgnoreApi = true)] to the endpoints I want to exclude and everyone is happy I think Atleast I tested and it behaves as expected Thank you for your suggestion!

Tvde1•2y ago

Perfect!

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ IHealthCheck and Swagger