Kubernetes Pod 无法使用服务与另一个 Pod 通信

Question

I have 2 Pods with 1 container each. The container names are:

1. mc1
2. mc2

mc1 container hosts an asp.net core razor pages app while mc2 hosts a web api app. Now mc1 has to communicate with mc2 ie razor page app has to call web api app.

I have tried to explain it in the below image:

I created 2 deployments for these 2 pods:

name: dep1
labels:
    app: mc-app1
spec:
  replicas: 1
  selector: 
    matchLabels:
      app: mc-app1
  template:
    metadata: 
      labels:
        app: mc-app1
    spec:
      containers:
        - name: mc1
          image: multiapp
          imagePullPolicy: Never
          ports:
            - containerPort: 80
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: dep2
  labels:
    app: mc-app2
spec:
  replicas: 1
  selector: 
    matchLabels:
      app: mc-app2
  template:
    metadata: 
      labels:
        app: mc-app2
    spec:
      containers:
        - name: mc2
          image: multiapi
          imagePullPolicy: Never
          ports:
            - containerPort: 80

I also created a service for the POD containing the mc2 container (ie web api app).

apiVersion: v1
kind: Service
metadata:
  name: multi-container-service-2
spec:
  type: NodePort
  selector:
    app: mc-app2
  ports:
    - port: 8080
      targetPort: 80

The deployments and services are successfully applied to the k8s cluster.

Next, I am entering the container "mc1" and trying to curl the service called multi-container-service-2 but this is not working.

I am getting error:

curl: (7) Failed to connect to multi-container-service-2 port 80: Connection refused

In the below image I am entering the shell of the container mc1 with the command:

kubectl exec -it dep1-5c78b8c889-tjzzr -c mc1 -- /bin/bash

In the next image I am doing the curl which is giving error:

Note that I have already installed curl using the 2 commands given below:

apt-get update
apt-get install curl

Why can't the app in mc2 container be called using the service? My Operating system is windows 10.

I am taking the help of these 2 tutorials:

1. Build ASP.NET Core applications deployed as Linux containers into an AKS/Kubernetes orchestrator
2. Communicate Between Containers in the Same Pod Using a Shared Volume

Answer 1

You have set to service port to 8080 , but you are calling the service on port 80 (which is the container's port).

This should work:

curl http://multi-container-service-2:8080

Answer 2

As stated in the official kubernetes documentation:

Kubernetes creates DNS records for services and pods. You can contact services with consistent DNS names instead of IP addresses.

In order to communicate Pod-to-Pod through a service in your cluster you have to use the following syntax:

{service_name}.{namespace}.svc.cluster.local

So in your case, with curl it would be:

curl multi-container-service-2.default.svc.cluster.local