I have a kubernetes cluster that comprises my application and a database that I host on a separate VM instance (outside of the cluster). The database should be listening on port 27017 (I confirm this using netstat). I want to be able for my services in my cluster to connect to this database. I recieve errors about the connection timing out. This leads me to believe that a) the service discovery in my cluster is not working correctly (most likely a configuration issue) or b) there is some firewall that is blocking my requests.

To allow my external database to be discovered, I have defined a service and a custom endpoint for my database. Here is the service definition:

kind: Service
apiVersion: v1
metadata:
 name: db-service
 namespace: production
spec:
  ports:
    - protocol: TCP
      port: 27017
      targetPort: 27017

Here is the endpoint definition:

kind: Endpoints
apiVersion: v1
metadata:
 name: db-service
 namespace: production
subsets:
 - addresses:
     - ip: <internal-ip>
   ports:
     - port: 27017

I have tried using both the external and internal ips for the endpoint definition (using the internal ip makes the most sense to me).

The only network tags I have on my VM instance hosting my database is 'http-server' and 'https-server' (default tags allowing for http/https traffic).

What in my approach is preventing requests from nodes in my cluster from being received by my db being hosted on the VM instance?