OpenShift container to container localhost communication not working in a pod

Question

I am trying to implement a SideCar pattern in OpenShift. My example has two Project API's. I am running the two Projects in different containers and in a single pod. Below is my deployment config specifying 2 images.

 containers:
        - env:
            - name: ASPNETCORE_URLS
              value: 'http://*:8080'
          image: 'docker-registry.default.svc:5000/it-mfg/hello-api-n:4.0'
          imagePullPolicy: Always
          name: hello-api-n
          ports:
            - containerPort: 8080
              name: http
              protocol: TCP
          resources: {}
          terminationMessagePath: /dev/termination-log
          terminationMessagePolicy: File
        - env:
            - name: ASPNETCORE_URLS
              value: 'http://*:8090'
          image: 'docker-registry.default.svc:5000/it-mfg/hello-sidecar-api-n:4.0'
          imagePullPolicy: Always
          name: hello-sidecar-api-n
          ports:
            - containerPort: 8090
              name: http
              protocol: TCP
          resources: {}

I want to hit the api from one container to api in another container through localhost. When I go to the Pod Terminal and select hello-api-n container and do http://localhost:8080/FromSidecar, the communication is not happenning.

Actually when I hit /FromSidecar the internal code implementaion makes a API call to localhost:8090/hello which is a different container.

Below is the error I am facing

I have no name!@hello-api-n-deployment-config-3-xvlsd:/app$ curl -v http://localhost:8080/FromSidecar
* Uses proxy env variable no_proxy == 'localhost'
*   Trying ::1:8080...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET /FromSidecar HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.68.0
> Accept: */*
>
* Mark bundle as not supporting multiuse
< HTTP/1.1 404 Not Found
< Date: Wed, 05 May 2021 09:00:22 GMT
< Server: Kestrel
< Content-Length: 0
<
* Connection #0 to host localhost left intact
I have no name!@hello-api-n-deployment-config-3-xvlsd:/app$

The example I am trying to do is from below https://github.com/cesaroll/dotnet-sidecar

UPDATED CODE:

Project A Container code:

 [HttpGet]
        [Route("FromSidecar")]
        public async Task<IActionResult> GetFromSidecar()
        {
            return Ok(await _helloService.RetrieveHelloMessage());
        }

HelloService:

 public async Task<HelloMessage> RetrieveHelloMessage()
        {
            //string sidecarUrl = configuration.GetSection("SideCar").GetSection("SideCarUrl").Value;
            
           **string URL = "http://localhost:8090/Hello" /// hitting Container B**
            var client = new HttpClient();

            var response = client.GetAsync(URL).Result;

            if (!response.IsSuccessStatusCode)
            {
                return new HelloMessage()
                {
                    Message = $"Error Status Code: {response.StatusCode}, Reason: {response.ReasonPhrase}"
                };
            }
                
            _logger.LogInformation(response.Content.ReadAsStringAsync().Result);
                
            var helloMessage = await response.Content.ReadFromJsonAsync<HelloMessage>();
                
            _logger.LogInformation(helloMessage?.Message);

            return helloMessage;

        }

PROJECT B Container code:

  public IActionResult Get()
        {
            return Ok(new {Message = "Hello from Sidecar Api"});
        }

score 0 · Answer 1 · answered May 05 '21 at 14:22

0

The communication is working fine, as you can see the response HTTP/1.1 404 Not Found from the container. The error 404 means the resource you are looking is not there. The connection is established Connected to localhost

answered May 05 '21 at 14:22

Suresh Vishnoi

17,341
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Yes, Thanks for your reply, when I do curl http://localhost:8080/FromSidecar from Container A, it internall hits http://localhost:8090/hello to the response from Container B, this container to container communication is not happenning, when I do Curl from Individual containers they are working fine. – user804401 May 05 '21 at 14:45
sorry, I could not understand your situation. Communication is happening, but you want to achieve something different here – Suresh Vishnoi May 05 '21 at 14:58
Sorry that I Could explain clearly, I have one API in a project and is running in a container in openshift, This API hits another API in another container. Both the containers are running in a single pod. One Container in Port 8080 and another in 8090. When I do http://localhost:8080/FromSidecar it calls the another API in another container with port 8090. Here is where I am getting 404. I have updated the code for your understanding – user804401 May 05 '21 at 15:21

OpenShift container to container localhost communication not working in a pod

1 Answers1