Kubernetes MongoDB replicaset creation failed

Question

What i intended to do:

Setup Kubernetes in Digital Ocean
Configure MongoDB replicaset in kubernetes

EDIT: Steps that i used to setup Kubernetes

Steps to setup master node:

Docker Setup using : https://kubernetes.io/docs/setup/production-environment/container-runtimes/#docker

$ sudo apt-get install -y kubelet kubeadm kubectl
$ kubeadm init —pod-network-cidr=192.168.0.0/16 —apiserver-advertise-address=
$ kubectl apply -f https://docs.projectcalico.org/v3.14/manifests/calico.yaml

Kubernetes Version: v1.18.3 Docker Version: 19.03.8, build afacb8b7f0

Setting Up Nodes:

Docker Setup using : https://kubernetes.io/docs/setup/production-environment/container-runtimes/#docker

$ sudo apt-get install -y kubelet kubeadm kubectl
$ kubeadm join :6443 --token  \
    --discovery-token-ca-cert-hash

I have completed step1 successfully but unable to configure repliaca set. The rs.initiate() command fails with "No host described in new configuration 1 for replica set rs0 maps to this node" error.

$kubectl get all
NAME                                         READY   STATUS    RESTARTS   AGE
pod/mongo-0                                  1/1     Running   0          16m
pod/mongo-1                                  1/1     Running   0          16m
pod/mongo-2                                  1/1     Running   0          16m
pod/nfs-client-provisioner-5d7cbcd58-qs8r6   1/1     Running   0          43h

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)     AGE
service/kubernetes   ClusterIP   10.96.0.1            443/TCP     2d21h
service/mongo        ClusterIP   None                 27017/TCP   16m

NAME                                     READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/nfs-client-provisioner   1/1     1            1           43h

NAME                                               DESIRED   CURRENT   READY   AGE
replicaset.apps/nfs-client-provisioner-5d7cbcd58   1         1         1       43h

NAME                     READY   AGE
statefulset.apps/mongo   3/3     16m

Below command fails:

$kubectl exec -it mongo-0 -- mongo
MongoDB shell version v4.2.7
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("64863831-2775-488f-a80d-aabdeb84bad9") }
MongoDB server version: 4.2.7
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
    http://docs.mongodb.org/
Questions? Try the support group
    http://groups.google.com/group/mongodb-user
Server has startup warnings: 
2020-05-31T09:46:16.537+0000 I  CONTROL  [initandlisten] 
2020-05-31T09:46:16.537+0000 I  CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2020-05-31T09:46:16.537+0000 I  CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2020-05-31T09:46:16.537+0000 I  CONTROL  [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2020-05-31T09:46:16.538+0000 I  CONTROL  [initandlisten] 
---
Enable MongoDB's free cloud-based monitoring service, which will then receive and display
metrics about your deployment (disk utilization, CPU, operation statistics, etc).

The monitoring data will be available on a MongoDB website with a unique URL accessible to you
and anyone you share the URL with. MongoDB may use this information to make product
improvements and to suggest MongoDB products and deployment options to you.

To enable free monitoring, run the following command: db.enableFreeMonitoring()
To permanently disable this reminder, run the following command: db.disableFreeMonitoring()
---

> rs.initiate({_id: "rs0", version: 1, members: [
...   { _id: 0, host : "mongo-0.mongo:27017" },
...   { _id: 1, host : "mongo-1.mongo:27017" },
...   { _id: 2, host : "mongo-2.mongo:27017" }
... ]});
{
    "operationTime" : Timestamp(0, 0),
    "ok" : 0,
    "errmsg" : "No host described in new configuration 1 for replica set rs0 maps to this node",
    "code" : 93,
    "codeName" : "InvalidReplicaSetConfig",
    "$clusterTime" : {
        "clusterTime" : Timestamp(0, 0),
        "signature" : {
            "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
            "keyId" : NumberLong(0)
        }
    }
}

My yamls files:

1.Headless service:

apiVersion: v1
kind: Service
metadata:
  name: mongo
  labels:
    app: mongo
spec:
  ports:
  - name: mongo
    port: 27017
    targetPort: 27017
  clusterIP: None
  selector:
    app: mongo

mongodb replicate set

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mongo
spec:
  selector:
    matchLabels:
       app:  mongo
  serviceName: "mongo"
  replicas: 3
  template:
    metadata:
      labels:
        app: mongo
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: mongo
        image: mongo
        command:
        - mongod
        - "--replSet"
        - rs0
        - "--bind_ip_all"
        ports:
        - containerPort: 27017
        volumeMounts:
        - name: mongo-volume
          mountPath: /data/db
  volumeClaimTemplates:
  - metadata:
      name: mongo-volume
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 10Gi

The issue may be due to DNS. I did the below to fix it with no success:

Ensured 27017 is open in Master and worker nodes

$ufw allow 27017

In .yaml tried to set "bind_ip" in .yaml file to 127.0.0.1 and 0.0.0.0

Nothing worked.

How to fix this issue?

Kubernetes MongoDB replicaset creation failed

Answers (1)

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