Cannot assign requested address

[cpiock]

I have done my first example with oclet with docker. I have 2 images 1 is my ocelot apigateway running on localhost:6002 and one is my api running on localhost:6001

  my.api:
    environment:
      - ASPNETCORE_ENVIRONMENT=Development
      - ASPNETCORE_URLS=http://0.0.0.0:80
      - ConnectionString=${AuthenticationDB_PROD:-Server=sql.data;Database=AuthenticationDb;User Id=SA;Password=Pass@word}
      - UseCustomizationData=True
      - AzureServiceBusEnabled=False
      - AzureStorageEnabled=False
    ports:
      - "6001:80"  

  apigateway.api:
    environment:
      - ASPNETCORE_ENVIRONMENT=Development
      - ASPNETCORE_URLS=http://0.0.0.0:80
      - UseCustomizationData=True
      - AzureServiceBusEnabled=False
      - AzureStorageEnabled=False
    ports:
      - "6002:80"`

Here my config:

{
  "ReRoutes": [
    {
      "DownstreamPathTemplate": "/api/{version}/{everything}",
      "DownstreamScheme": "http",
      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 6001
        }
      ],
      "UpstreamPathTemplate": "/api/auth/{version}/{everything}",
      "UpstreamHttpMethod": []
    }
  ]

If I run http://localhost:6001/api/v1/authentication/authenticate everything works fine. But if I call this endpoint trough the apigateway I see in the logs the following error

Ocelot.Responder.Middleware.ResponderMiddleware[0]
      requestId: 0HLLV201IGIHI:0000000C, previousRequestId: no previous request id, 
message: 
  Error Code: UnableToCompleteRequestError 
  Message: Error making http request, 
    exception: System.Net.Http.HttpRequestException: Cannot assign requested address
    ---> System.Net.Sockets.SocketException: Cannot assign requested address

I see that ocelot is trying to call this url and calling this with postman it works fine
Downstream url is http://localhost:6001/api/v1/authentication/authenticate

I think I made some beginner error but I can't find him
Thanks

[tomhobson]

I'm also experiencing this issue. This is specifically with a dockerized gateway. I have run a standard gateway and can get it to reach the apis fine. with an exact duplicate config.json.

it seems to be resolving the downstream urls correctly, I can copy and paste them from the console into postman and they run just fine.

Here's my config.json
{ "ReRoutes": [ { "DownstreamPathTemplate": "/api/PropertySearch/{url}", "DownstreamScheme": "http", "DownstreamHostAndPorts": [ { "Host": "localhost", "Port": 60357 } ], "UpstreamPathTemplate": "/PropertySearch/{url}", "UpstreamHttpMethod": [ "Get" ] } ], "GlobalConfiguration": { "RequestIdKey": "OcRequestId", "AdministrationPath": "/administration" } }

And my error logs.

[40m�[32minfo�[39m�[22m�[49m: Microsoft.AspNetCore.Hosting.Internal.WebHost[1] Request starting HTTP/1.1 GET http://localhost:53148/PropertySearch/GetProperty/LS1 3AD Microsoft.AspNetCore.Hosting.Internal.WebHost:Information: Request starting HTTP/1.1 GET http://localhost:53148/PropertySearch/GetProperty/LS1 3AD Ocelot.Errors.Middleware.ExceptionHandlerMiddleware:Debug: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: ocelot pipeline started �[40m�[37mdbug�[39m�[22m�[49m: Ocelot.Errors.Middleware.ExceptionHandlerMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: ocelot pipeline started Ocelot.DownstreamRouteFinder.Middleware.DownstreamRouteFinderMiddleware:Debug: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: Upstream url path is /PropertySearch/GetProperty/LS1%203AD �[40m�[37mdbug�[39m�[22m�[49m: Ocelot.DownstreamRouteFinder.Middleware.DownstreamRouteFinderMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: Upstream url path is /PropertySearch/GetProperty/LS1%203AD Ocelot.DownstreamRouteFinder.Middleware.DownstreamRouteFinderMiddleware:Debug: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: downstream templates are /api/PropertySearch/{url} �[40m�[37mdbug�[39m�[22m�[49m: Ocelot.DownstreamRouteFinder.Middleware.DownstreamRouteFinderMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: downstream templates are /api/PropertySearch/{url} �[40m�[32minfo�[39m�[22m�[49m: Ocelot.RateLimit.Middleware.ClientRateLimitMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: EndpointRateLimiting is not enabled for /api/PropertySearch/{url} Ocelot.RateLimit.Middleware.ClientRateLimitMiddleware:Information: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: EndpointRateLimiting is not enabled for /api/PropertySearch/{url} �[40m�[32minfo�[39m�[22m�[49m: Ocelot.Authentication.Middleware.AuthenticationMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: No authentication needed for /PropertySearch/GetProperty/LS1%203AD Ocelot.Authentication.Middleware.AuthenticationMiddleware:Information: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: No authentication needed for /PropertySearch/GetProperty/LS1%203AD Ocelot.Authorisation.Middleware.AuthorisationMiddleware:Information: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: /api/PropertySearch/{url} route does not require user to be authorised �[40m�[32minfo�[39m�[22m�[49m: Ocelot.Authorisation.Middleware.AuthorisationMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: /api/PropertySearch/{url} route does not require user to be authorised �[40m�[37mdbug�[39m�[22m�[49m: Ocelot.DownstreamUrlCreator.Middleware.DownstreamUrlCreatorMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: Downstream url is http://localhost:60357/api/PropertySearch/GetProperty/LS1%203AD Ocelot.DownstreamUrlCreator.Middleware.DownstreamUrlCreatorMiddleware:Debug: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: Downstream url is http://localhost:60357/api/PropertySearch/GetProperty/LS1%203AD �[40m�[37mdbug�[39m�[22m�[49m: Ocelot.Requester.Middleware.HttpRequesterMiddleware[0] requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: IHttpRequester returned an error, setting pipeline error Ocelot.Requester.Middleware.HttpRequesterMiddleware:Debug: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: IHttpRequester returned an error, setting pipeline error Ocelot.Requester.Middleware.HttpRequesterMiddleware:Warning: requestId: 0HLLV2V8LEGC4:00000006, previousRequestId: no previous request id, message: Error making http request, exception: System.Net.Http.HttpRequestException: Cannot assign requested address ---> System.Net.Sockets.SocketException: Cannot assign requested address at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken) --- End of inner exception stack trace --- at System.Net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, CancellationToken cancellationToken) at System.Threading.Tasks.ValueTask1.get_Result()
at System.Net.Http.HttpConnectionPool.CreateConnectionAsync(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Threading.Tasks.ValueTask1.get_Result() at System.Net.Http.HttpConnectionPool.WaitForCreatedConnectionAsync(ValueTask1 creationTask)
at System.Threading.Tasks.ValueTask1.get_Result() at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken) at System.Net.Http.HttpClient.FinishSendAsyncBuffered(Task1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts)
at Ocelot.Requester.HttpClientHttpRequester.GetResponse(DownstreamContext context)`

I have also disabled https to try to simplify the issue further. On both the apis and the gateway.

[raman-m]

You can upload your DLL binary body for verification. 😉

[cpiock]

Any suggestions?

[tomhobson]

I think it has something to do with the docker routing. Might be worth trying to point to the actual container IP while this issue gets fixed.

docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' container_name_or_id
(gets you the docker container ip)

[markosmilja]

I had a similar problem, I think docker has an internal DNS server or something and localhost doesn't mean the same thing to a native and a dockerized app. Anyway, if you are using docker-compose, you can use their service names as their IP addresses. ⚠️

So in the ocelot.json file, instead of:

      "DownstreamHostAndPorts": [
        {
          "Host": "localhost",
          "Port": 6001 
        }
      ],

you write,

      "DownstreamHostAndPorts": [
        {
          "Host": "my.api", // !!!
          "Port": 6001 
        }
      ],

Hope it helps!

[raman-m]

@markosmilja
Hello, Markos!
Absolutely right! 🎉
When we work with multiple services and webapp instances being wrapped into Docker container, then we have to create default Docker network via docker-compose command.
As soon as network artifact is created in Docker environment and composing all services/containers has done, then all service instances can communicate to each other without problems referencing simple service name as host name. So, we should care about ports too.

@cpiock FYI ❕
This is the answer.