I'm looking to configure Redis for Sidekiq and Rails in k8s. Using Google Cloud Memory Store with an IP address.
I have a helm template like the following (with gcpRedisMemorystore specified separately) - My question is what does the Service object add to the system? Is it necessary or does the Endpoint provide all the needed access?
charts/app/templates/app-memorystore.service.yaml
kind: Service
apiVersion: v1
metadata:
name: app-memorystore
spec:
type: ClusterIP
clusterIP: None
ports:
- name: redis
port: {{ .Values.gcpredis.port }}
protocol: TCP
---
kind: Endpoints
apiVersion: v1
metadata:
name: app-memorystore
subsets:
- addresses:
- ip: {{ .Values.gcpredis.ip }}
ports:
- port: {{ .Values.gcpredis.port }}
name: redis
protocol: TCPYes, you still need it.
Generally speaking, the Service is the name which is consumed by applications to connect to an Endpoint. Usually, a Service with a selector will automatically create a corresponding endpoint with the IP addresses of the Pods found by the selector.
When you define a Service without a selector you need to give the corresponding Endpoint of the same name so the Service has somewhere to go. This bit of information is in documentation but a bit buried. At https://kubernetes.io/docs/concepts/services-networking/service/#without-selectors it is mentioned in the second bullet point for headless services without selectors:
For headless services that do not define selectors, the endpoints controller does not create Endpoints records. However, the DNS system looks for and configures either:
- CNAME records for ExternalName-type services.
- A records for any Endpoints that share a name with the service, for all other types.