Kubernetes Postgres Pod 无法访问

Question

I have a K8s Cluster with couple of pods. I have a postgres pod of type Deployment which simply runs a "postgres:12" image

docker pull postgres:12

the pod is named "metadatadb"

there are other pods of type Cronjob that are dependent on it. from time to time I see some of these cronjob instances failing with the below error

ERROR [08001] could not translate host name "metadatadb" to address: Name or service not known

This error happens rarely (which means in most of the times the cronjob runs and connects successfully). I can't figure out why.

Thank you

Answer 1

The error is the result of a missing Service or a problem with the Cluster DNS.

Background: A pod does not get a DNS entry, if you want to connect to a pod you need the internal IP of it. To create DNS names (and internal load balancing with a service ip) you need to create a service.