Mongo service is unavailable when the kubernetes runner executes the test job

Summary

Our CI runs tests using the mongo service and this works fine on the shared runners. I recently installed the GitLAB runner helm chart and added a group runner. Whenever the job is executed by this runner the test fail.

The error is: MongoNetworkError: failed to connect to server [mongo:27017] on first connect [MongoNetworkError: getaddrinfo EAI_AGAIN mongo mongo:27017]

Steps to reproduce

Use the mongo service on a non-shared Kubernetes runner

What is the current bug behavior?

MongoNetworkError: failed to connect to server [mongo:27017] on first connect [MongoNetworkError: getaddrinfo EAI_AGAIN mongo mongo:27017]

What is the expected correct behavior?

Connect to MongoDB correctly

Output of checks

This bug happens on GitLab.com but with our own runner on an Azure Kubernetes cluster