Grpc connection in kubernetes is not working =>UNAVAILABLE: Network closed for unknown reason

• Your deployment yamls are lacking the service part to route the traffic to the pods appropriately.
• Also, the deployments are not passing the Environment Variables as specified in the docker-compose.yml. Here are the fixed yamls.
• deployment_server.yml:

apiVersion: apps/v1kind: Deploymentmetadata:  labels:    app.kubernetes.io/name: grpc-server  name: grpc-serverspec:  replicas: 1  selector:    matchLabels:      app.kubernetes.io/name: grpc-server  template:    metadata:      labels:        app.kubernetes.io/name: grpc-server    spec:      containers:      - image: poc_grpc-server:latest        imagePullPolicy: Never        name: grpc-server        ports:        - containerPort: 8081        env:        - name: GRPC_SERVER_PORT          value: "8081"---apiVersion: v1kind: Servicemetadata:  name: grpc-server-svcspec:  selector:    app.kubernetes.io/name: grpc-server  ports:    - protocol: TCP      port: 8081

• deployment_client.yml:

apiVersion: apps/v1kind: Deploymentmetadata:  labels:    app.kubernetes.io/name: grpc-client  name: grpc-clientspec:  replicas: 1  selector:    matchLabels:      app.kubernetes.io/name: grpc-client  template:    metadata:      labels:        app.kubernetes.io/name: grpc-client    spec:      containers:      - image: poc_grpc-client        imagePullPolicy: Never        name: grpc-client        ports:        - containerPort: 8080        env:           - name: GRPC_SERVER_ADDRESS            value: "grpc-server-svc"          - name: GRPC_SERVER_PORT            value: "8081"---apiVersion: v1kind: Servicemetadata:  name: grpc-client-svcspec:  selector:    app.kubernetes.io/name: grpc-client  ports:    - protocol: TCP      port: 8080  type: NodePort

Highlights:

• created grpc-server-svc service as ClusterIP to be available only inside the cluster serving the GRPC Server.
• created grpc-client-svc service to NodePort to demonstrate receiving curl requests from outside the cluster.
• Added the env section: Note that I set GRPC_SERVER_ADDRESS to grpc-server-svc since we are not in docker environment anymore host.docker.internal is no longer an option we are now targetting the service mentioned above.
• I'm using imagePullPolicy set to Never only for this example, since I'm using my local docker registry.

Reproduction:

• After building the images:

$ docker image lsREPOSITORY                                TAG                 IMAGE ID            CREATED             SIZEpoc_grpc-client                           latest              7f6d886a1612        24 minutes ago      660MBpoc_grpc-server                           latest              d46bf9481d1c        24 minutes ago      658MB

• Deployed the fixed yamls as above:

$ kubectl apply -f deployment_server.yml deployment.apps/grpc-server createdservice/grpc-server-svc created$ kubectl apply -f deployment_client.yml deployment.apps/grpc-client createdservice/grpc-client-svc created$ kubectl get allNAME                               READY   STATUS    RESTARTS   AGEpod/grpc-client-6ffcf6b6c8-846s5   1/1     Running   0          3spod/grpc-server-5d7fd9cb89-dkqlb   1/1     Running   0          7sNAME                      TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGEservice/grpc-client-svc   NodePort    10.99.58.76    <none>        8080:32224/TCP   3sservice/grpc-server-svc   ClusterIP   10.96.67.139   <none>        8081/TCP         7sservice/kubernetes        ClusterIP   10.96.0.1      <none>        443/TCP          3h36mNAME                          READY   UP-TO-DATE   AVAILABLE   AGEdeployment.apps/grpc-client   1/1     1            1           3sdeployment.apps/grpc-server   1/1     1            1           7sNAME                                     DESIRED   CURRENT   READY   AGEreplicaset.apps/grpc-client-6ffcf6b6c8   1         1         1       3sreplicaset.apps/grpc-server-5d7fd9cb89   1         1         1       7s

• Now I'll curl the client, since I'm running on minikube (1 node cluster) the IP of the node is the IP of the cluster, I'll pair the IP with the NodePort assigned.

$ kubectl cluster-infoKubernetes master is running at https://172.17.0.4$ curl http://172.17.0.4:32224Client is running!!!$ curl http://172.17.0.4:32224/hello?firstName=CedricHello Cedric

If you have any questions, let me know in the comments!