I would like to connect my Kubernetes Deployment to a remotely hosted database with URI.

I am able to connect to remotely hosted database with URI using Docker. Now I'd like to understand how I can specify multiple external names in Kubernetes service file.

I have a MongoDB cluster with the below URL:

mongodb://username:password@mngd-new-pr1-01:27017,mngd-new-pr2-02:27017,mngd-new-pr3-03:27017/

I have followed Kubernetes best practices: mapping external services. When I setup a single external name, it is working.

How can I specify all the 3 clusters in the external name?

kind: Service
apiVersion: v1
metadata:
 name: mongo
spec:
  type: ExternalName
  externalName: mngd-new-pr1-01,mngd-new-pr2-02,mngd-new-pr3-03
  ports:
  - port: 27017

since i was unable to create the multiple external names .

I went with creating the headless service and then created the endpoints for the service .As described "Scenario 1: Database outside cluster with IP address"

From the logs , I think the connectivity is being established . but later there was exception like below and it was disconnected .

2019-03-20 11:26:13.941 INFO 1 --- [38.200.19:27038] org.mongodb.driver.connection : Opened connection [connectionId{localValue:1, serverValue:386066}] to .38.200.19:27038
2019-03-20 11:26:13.953 INFO 1 --- [.164.29.4:27038] org.mongodb.driver.connection : Opened connection [connectionId{localValue:2, serverValue:458254}] to .164.29.4:27038
2019-03-20 11:26:13.988 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Monitor thread successfully connected to server with description ServerDescription{address=.38.200.19:27038, type=REPLICA_SET_PRIMARY, state=CONNECTED, ok=true, version=ServerVersion{versionList=[3, 6, 8]}, minWireVersion=0, maxWireVersion=6, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=30, roundTripTimeNanos=45440955, setName='no-prd-rep', canonicalAddress=mngd-new-pr1-01:27038, hosts=[mngd-new-pr1-01:27038, mngd-new-pr1-02:27038, mngd-new-pr1-03:27038], passives=[], arbiters=[], primary='mngd-new-pr1-01:27038'
2019-03-20 11:26:13.990 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Adding discovered server mngd-new-pr1-01:27038 to client view of cluster
2019-03-20 11:26:13.992 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Adding discovered server mngd-new-pr1-02:27038 to client view of cluster
2019-03-20 11:26:13.993 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Adding discovered server mngd-new-pr1-03:27038 to client view of cluster
2019-03-20 11:26:13.997 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Server 102.227.4:27038 is no longer a member of the replica set. Removing from client view of cluster.
2019-03-20 11:26:14.001 INFO 1 --- [.164.29.4:27038] org.mongodb.driver.cluster : Monitor thread successfully connected to server with description ServerDescription{address=.164.29.4:27038, type=REPLICA_SET_SECONDARY, state=CONNECTED, ok=true, version=ServerVersion{versionList=[3, 6, 8]}, minWireVersion=0, maxWireVersion=6, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=30, roundTripTimeNanos=47581993, setName='no-prd-rep', canonicalAddress=mngd-new-pr1-01:27038, hosts=[mngd-new-pr1-01:27038, mngd-new-pr1-02:27038, mngd-new-pr1-03:27038], passives=[], arbiters=[], primary='mngd-new-pr1-01:27038',
2019-03-20 11:26:14.001 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Server 38.200.19:27038 is no longer a member of the replica set. Removing from client view of cluster.
2019-03-20 11:26:14.001 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Server 164.29.4:27038 is no longer a member of the replica set. Removing from client view of cluster.
2019-03-20 11:26:14.001 INFO 1 --- [38.200.19:27038] org.mongodb.driver.cluster : Canonical address mngd-new-pr1-01:27038 does not match server address. Removing .38.200.19:27038 from client view of cluster
2019-03-20 11:26:34.012 INFO 1 --- [2-prd2-01:27038] org.mongodb.driver.cluster : Exception in monitor thread while connecting to server mngd-new-pr1-01:27038
com.mongodb.MongoSocketException: mngd-new-pr1-01: Name or service not known
at com.mongodb.ServerAddress.getSocketAddress(http://ServerAddress.java:188 ) ~[mongodb-driver-core-3.6.4.jar!/:na]

So since we are using the endpoints as ip address and its not matching with the connection string specified in the deployment yaml connection string it might be failing . Really confusing me a lot :)

PS : to check the connectivity to external mongo cluster i have launched the single pod

apiVersion: v1
kind: Pod
metadata:
  name: proxy-chk
spec:
  containers:
  - name: centos
    image: centos
    command: ["/bin/sh", "-c", "while : ;do curl -L http://${MONGODBendpointipaddress}:27038/; sleep 10; done"]

In the logs i can see the it is able to establish the connectivity .

" It looks like you are trying to access MongoDB over HTTP on the native driver port. "

So i think the headless service which i created earlier its able to route the traffic

Need your advise .