I have a problem with service (DNS) discovery in kubernetes 1.14 version in ubuntu bionic.

Right now my 2 pods communicating using IP addresses. How can I enable coredns for service (DNS) discovery?

Here is the output of kubectl for service and pods from kube-system namespace:

    kubectl get pods,svc --namespace=kube-system | grep dns
    pod/coredns-fb8b8dccf-6plz2          1/1     Running            0          6d23h
    pod/coredns-fb8b8dccf-thxh6          1/1     Running            0          6d23h

    service/kube-dns        ClusterIP   10.96.0.10       <none>        53/UDP,53/TCP,9153/TCP   6d23h

I have installed kubernetes on master node(ubuntu bionic machine) using below steps

    apt-get update
    apt-get install     apt-transport-https     ca-certificates     curl     gnupg-agent     software-properties-common
    curl -fsSL https://download.docker.com/linux/ubuntu/gpg | apt-key add -
    add-apt-repository    "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
    apt-get update
    apt-get install docker-ce docker-ce-cli containerd.io
    apt-get update && apt-get install -y apt-transport-https curl
    curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -

    cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
    deb https://apt.kubernetes.io/ kubernetes-xenial main
    EOF

    apt-get update
    apt-get install -y kubelet kubeadm kubectl
    kubectl version
    apt-mark hold kubelet kubeadm kubectl
    kubeadm config images pull
    swapoff -a
    kubeadm init

    mkdir -p $HOME/.kube
    cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
    chown $(id -u):$(id -g) $HOME/.kube/config
    sysctl net.bridge.bridge-nf-call-iptables=1
    kubectl apply -f "https://cloud.weave.works/k8s/net?k8s-version=$(kubectl version | base64 | tr -d '\n')"
    kubectl get pods --all-namespaces

This is on worker node

    Docker is already installed, so directly installing kubernetes on worker node
    apt-get update && apt-get install -y apt-transport-https curl
    curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add -
    cat <<EOF >/etc/apt/sources.list.d/kubernetes.list
    deb https://apt.kubernetes.io/ kubernetes-xenial main
    EOF

    apt-get update
    apt-get install -y kubelet kubeadm kubectl
    kubectl version
    apt-mark hold kubelet kubeadm kubectl
    swapoff -a
    Now joined worker node to master

Answer:-

I think everything was setup correctly by default, There was a misunderstanding by me that I can call a server running in one pod from another pod using the container name and port which I have specified in spec, but instead I should use service name and port.

Below is my deployment spec and service spec:-

Deployment spec:-

    apiVersion: extensions/v1beta1
    kind: Deployment
    metadata:
      name: node-server1-deployment
    spec:
      replicas: 1
      template:
    metadata:
      labels:
        app: node-server1
    spec:
      hostname: node-server1
      containers:
      - name: node-server1
        image: bvenkatr/node-server1:1
        ports:
        - containerPort: 5551

Service spec:

    kind: Service
    apiVersion: v1
    metadata:
      name: node-server1-service
    spec:
      selector:
         app: node-server1
      ports:
      - protocol: TCP
        port: 5551