Kubernetes node.js container cannot connect to MongoDB Atlas

I figured out the issue, my pod DNS was not configured to allow external connections, so I set dnsPolicy: Default in my YML, because oddly enough Default is not actually the default value

I use MongoDB Atlas from Kubernetes but on AWS. Although for testing purposes you can enable all IP addresses and test, here is the approach for a production setup:

• MongoDB Atlas supports Network Peering
• Under Network Access > New Peering Connection
• In the case of AWS, VPC ID, CIDR and Region have to be specified. For GCP it should be the standard procedure used for VPC peering.

Firstly, Pods are deployed on nodes in a cluster and not on your service (so Mongo won't recognise your service endpoints e.g; load balancer IP). Based on this, there are two solutions:

solution A

1. Add the endpoint of the Kubernetes cluster to the MongoDB network access IP whitelist.

2. Under the pod spec of your k8s pod (or deployment) manifest, add a dnsPolicy field with value set to Default. Hence, your Pods (your container basically) will connect to mongo through the name resolution configuration of the master node.

solution B

1. Add all node endpoints in your k8s cluster to the MongoDB network access IP whitelist.

2. Under the pod spec of your k8s pod (or deployment) manifest, add a dnsPolicy field with the value set to ClusterFirstWithHostNet. Since the pods run with your host network, they gain access to services listening on localhost.

Kubernetes documentation