mongodb connection string uri not working in the Kubernetes

Question

I have deployed mongodb as a StatefulSets on the K8S. It is not connecting, when I try to connect the DB using connection string URI(Ex: mongodb://mongo-0.mongo:27017,mongo-1.mongo:27017/cool_db), but it is connecting and getting the results when I use Endpoint IP Address.

# kubectl get sts
NAME    READY   AGE
mongo   2/2     7h33m

#kubectl get pods
NAME                                      READY   STATUS    RESTARTS   AGE
mongo-0                                   2/2     Running   0          7h48m
mongo-1                                   2/2     Running   2          7h47m

# kubectl get svc
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)     AGE
kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP     10h
mongo        ClusterIP   None         <none>        27017/TCP   7h48m

I'm trying to test the connection using connection string URI in the python using the below process but it fails.

>>> import pymongo
>>> client = pymongo.MongoClient("mongodb://mongo-0.mongo:27017,mongo-1.mongo:27017/cool_db")
>>> db = client.cool_db
>>> print db.cool_collection.count()
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/usr/lib64/python2.7/site-packages/pymongo/collection.py", line 1800, in count
   return self._count(cmd, collation, session)
 File "/usr/lib64/python2.7/site-packages/pymongo/collection.py", line 1600, in _count
   _cmd, self._read_preference_for(session), session)
 File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line 1454, in _retryable_read
   read_pref, session, address=address)
 File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line 1253, in _select_server
   server = topology.select_server(server_selector)
 File "/usr/lib64/python2.7/site-packages/pymongo/topology.py", line 235, in select_server
   address))
 File "/usr/lib64/python2.7/site-packages/pymongo/topology.py", line 193, in select_servers
   selector, server_timeout, address)
 File "/usr/lib64/python2.7/site-packages/pymongo/topology.py", line 209, in _select_servers_loop
   self._error_message(selector))
pymongo.errors.ServerSelectionTimeoutError: mongo-0.mongo:27017: [Errno -2] Name or service not known,mongo-1.mongo:27017: [Errno -2] Name or service not known

If we use the Endpoint IP Address, then we will get a response from DB.

>>> import pymongo
>>> client = pymongo.MongoClient("mongodb://10.244.1.8,10.244.2.9:27017/cool_db")
>>> db = client.cool_db
>>> print db.cool_collection.count()
0
>>>

I have tried with different URI's like (client = pymongo.MongoClient("mongodb://mongo-0.mongo:27017/cool_db") )but not working. Could anyone please help me?

You have only one mongo service running?

cogitoergosum
– cogitoergosum

2019-12-17 16:57:57 +00:00
Commented Dec 17, 2019 at 16:57 — cogitoergosum
– cogitoergosum, Commented Dec 17, 2019 at 16:57
any luck in this issue?

Raam Mishra
– Raam Mishra

2021-02-17 15:49:46 +00:00
Commented Feb 17, 2021 at 15:49 — Raam Mishra
– Raam Mishra, Commented Feb 17, 2021 at 15:49

Belly Buster · Accepted Answer · 2019-12-17 16:09:23Z

3

From my previous similar answer:

From within the cluster you should reference the MongoDB Pod using <service-name>.<namespace-name>.svc.cluster.local.

answered Dec 17, 2019 at 16:09

Belly Buster

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Comments

gpm · Accepted Answer · 2021-10-05 12:41:57Z

Had the same issue in a spring java connection when I used the mongodb-community-operator. Solution was, don't use the aggregated String, just use the service. So, in your case, instead of using a concatinated String of the pods like this

mongodb://mongo-0.mongo:27017,mongo-1.mongo:27017/cool_db

I used the service, which also was generated as a secret in my namespace and what was written under the key connectionString.standardSrv

mongodb+srv://<username>:<password>@mongo-svc.mongo.svc.cluster.local/cool_db?ssl=false

-> I'm assuming your sts is named mongo and your namespace is named mongo too. In that case, I could not set the username and password as extra parameters, only this one uri. But that worked.

udav · Accepted Answer · 2019-12-17 04:20:01Z

0

I think using mongodb://mongo-0:27017 should work

answered Dec 17, 2019 at 4:20

udav

1

6 Comments

ratnakar Over a year ago

Hi Udav, Thanks for your response, Tried it but getting the same error.

ratnakar Over a year ago

@udev, pymongo.errors.ServerSelectionTimeoutError: mongo-0:27017: [Errno -2] Name or service not known

Belly Buster Over a year ago

Is your pymongo app running in the same k8s cluster?

ratnakar Over a year ago

@BellyBuster, pymongo was installed using pip on the K8S master.

Wytrzymały Wiktor Over a year ago

Could you please tell us are you trying to connect within the same namespace?

|

BallmersLeak · Accepted Answer · 2020-08-12 04:01:08Z

just fresh from debugging this issue. Make sure that your mini-kube is using coredns. Mine was not and once I did a minikube delete and minikube start, things worked.

You need to see this

$ kubectl get deploy -n kube-system
NAME      READY   UP-TO-DATE   AVAILABLE   AGE
coredns   1/1     1            1           31s

or this

$ kubectl get po -n kube-system
NAME                               READY   STATUS    RESTARTS   AGE
coredns-66bff467f8-9h6qb           1/1     Running   0          46s
etcd-minikube                      1/1     Running   0          46s
kube-apiserver-minikube            1/1     Running   0          46s
kube-controller-manager-minikube   1/1     Running   0          45s
kube-proxy-d99lp                   1/1     Running   0          46s
kube-scheduler-minikube            1/1     Running   0          46s
storage-provisioner                1/1     Running   0          49s

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