Cannot connect to a mongodb service in a Kubernetes cluster - mongodb

Question

I have a Kubernetes cluster on Google Cloud, I have a database service, which is running in front of a mongodb deployment. I also have a series of microservices, which are attempting to connect to that datastore.
However, they can't seem to find the host.
apiVersion: v1
kind: Service
metadata:
labels:
name: mongo
name: mongo
spec:
ports:
- port: 27017
targetPort: 27017
selector:
name: mongo
Here's my mongo deployment...
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: mongo-deployment
spec:
replicas: 1
template:
metadata:
labels:
name: mongo
spec:
containers:
- image: mongo:latest
name: mongo
ports:
- name: mongo
containerPort: 27017
hostPort: 27017
volumeMounts:
- name: mongo-persistent-storage
mountPath: /data/db
volumes:
- name: mongo-persistent-storage
gcePersistentDisk:
pdName: mongo-disk
fsType: ext4
And an example of one of my services...
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: bandzest-artists
spec:
replicas: 1
template:
metadata:
labels:
name: bandzest-artists
spec:
containers:
- name: artists-container
image: gcr.io/<omitted>/artists:41040e8
ports:
- containerPort: 7000
imagePullPolicy: Always
env:
- name: DB_HOST
value: mongo
- name: AWS_BUCKET_NAME
value: <omitted>
- name: AWS_ACCESS_KEY_ID
value: <omitted>
- name: AWS_SECRET_KEY
value: <omitted>

Answer 1

First, check that the service is created
kubectl describe svc mongo
You should see it show that it is both created and routing to your pod's IP. If you're wondering what your pod's IP is you can check it out via
kubectl get po | grep mongo
Which should return something like: mongo-deployment-<guid>-<guid>, then do
kubectl describe po mongo-deployment-<guid>-<guid>
You should make sure the pod is started correctly and says Running not something like ImagePullBackoff. It looks like you're mounting a volume from a gcePersistentDisk. If you're seeing your pod just hanging out in the ContainerCreating state it's very likely you're not mounting the disk correctly. Make sure you create the disk before you try and mount it as a volume.
If it looks like your service is routing correctly, then you can check the logs of your pod to make sure it started mongo correctly:
kubectl logs mongo-deployment-<guid>-<guid>
If it looks like the pod and logs are correct, you can exec into the pod and make sure mongo is actually starting and working:
kubectl exec -it mongo-deployment-<guid>-<guid> sh
Which should get you into the container (Pod) and then you can try something like this to see if your DB is running.