I want to connect multiple microservices hosted on Google Kubernetes Engine to a MongoDB Atlas database.

All Deployments and Services inside the cluster are on the gitlab-managed-apps namespace.

I have created the following ExternalName Service:

mongo-external-name.yaml

kind: Service
apiVersion: v1
metadata:
  name: mongo
  namespace: gitlab-managed-apps
spec:
  type: ExternalName
  externalName: db_name.mrud5.mongodb.net

To connect to MongoDB Atlas I tried to use the ExternalName since using db_name.mrud5.mongodb.net would try to resolve to an internal service:

//connect.js
mongoose.connect(`mongodb+srv://${ global.DB_USER }:${ global.DB_PASSWORD }@mongo.gitlab-managed-apps.svc.cluster.local/${ global.DB_NAME }?retryWrites=true&w=majority`, {
		useNewUrlParser: true,
		useCreateIndex: true,
		useUnifiedTopology: true,
		useFindAndModify: false
	});

As per the deployments, I have them inside a couple of Helm Charts. I thought it had something to do with the dnsPolicy: ClusterFirst and I attempted to set it to dnsPolicy: Default, but that made no difference.

Upon executing bash on one of the pods, I have tried nslookup as suggested by many other issues, this is the result:

bash-5.0# nslookup mongo.gitlab-managed-apps.svc.cluster.local
Server:         10.1.0.10
Address:        10.1.0.10:53

    mongo.gitlab-managed-apps.svc.cluster.local     canonical name = db_name.mrud5.mongodb.net

    mongo.gitlab-managed-apps.svc.cluster.local     canonical name = db_name.mrud5.mongodb.net

I figured that if the pod can see the CNAME records there must be something else that I am not doing right.

I was unable to ping mongo.gitlab-managed-apps.svc.cluster.local

bash-5.0# ping mongo.gitlab-managed-apps.svc.cluster.local
ping: bad address 'mongo.gitlab-managed-apps.svc.cluster.local'

My cluster's master version is 1.15.11-gke.15. I did not create the cluster with this version, upon creation, Gitlab automatically chose 1.14.10. After reading multiple issues on GitHub, I understood that there were some issues with kube-dns on version 1.14.9. I, therefore, ran the command below to try to fix this.

kubectl set image deployment/kube-dns -n kube-system \
  kubedns=gcr.io/google_containers/k8s-dns-kube-dns-amd64:1.14.10 \
  dnsmasq=gcr.io/google_containers/k8s-dns-dnsmasq-nanny-amd64:1.14.10 \
  sidecar=gcr.io/google_containers/k8s-dns-sidecar-amd64:1.14.10

As I thought, this was not the solution either. Desperate, I upgraded the cluster to 1.15.11-gke.15 and kube-dns with the above command. That was not the solution either.

I don't think it causes this problem but I have posted below my Ingress controller:

ingress-service.yaml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/rewrite-target: /$1
    nginx.ingress.kubernetes.io/proxy-body-size: "100m"
    certmanager.k8s.io/cluster-issuer: letsencrypt-prod
    nginx.ingress.kubernetes.io/proxy-connect-timeout: "7200"
    nginx.ingress.kubernetes.io/proxy-read-timeout: "7200"
    nginx.ingress.kubernetes.io/proxy-send-timeout: "7200"
  name: ingress-service
  namespace: gitlab-managed-apps
spec:
  tls:
    - hosts:
        - my.host
      secretName: letsencrypt-prod
  rules:
    - host: my.host
      http:
        paths:
          - backend:
              serviceName: my-cluster-ip-service
              servicePort: 3000
            path: /?(.*)

Any suggestion is very much appreciated!