Sometimes you need to access a service in a namespace from a different one. For example, I've got an instance of Elasticsearch running in my monitoring namespace and want to send data to it from pods running in my application namespace.
You can reference it using its DNS name in a service in the namespace that it isn't running in.
For this example, Elasticsearch is running in my monitoring namespace and a new service needs to be created in the application namespace to reference it, add the following service:
#Used to get access to elasticsearch when it's running in a namespace other than monitoring
---
kind: Service
apiVersion: v1
metadata:
name: elastic-ns
namespace: application
spec:
type: ExternalName
externalName: <elasticsearch service>.<monitoring namespace>.svc.cluster.local
ports:
- port: 9200