【08】 Kubernets: Service

EDITORIAL words

 

When K8S first section we briefly mentioned that there are three operating modes Service: userspace / iptables / ipvs. And already know the current default in the new version it is ipvs, provided that in accordance with K8S when configured ipvs module.

 

 

Service Inventory

 

It has been known for short service in front of svc, so we can explain to view the list of direct parameters of resources in the following table:

svc
apiVersion			v1
kind			Service
metadata			And like any other, name / labels / namespace, etc.
spec
	clusterIP		IP defines Service, usually only when the configuration type is ClusterIP, and most of the time randomly assigned
	ports
		name	name
		nodePort	NodePort is used when the type, is larger than the native mapping port 30000
		port	Service port
		targetPort	Pod port
	selector		Tag selector, direct key-value pairs
	sessionAffinity		Configuring allocation rules, support ClientIP / None
	type		ExternalName, ClusterIP, NodePort, LoadBalancer (typically a cloud)

 

Simple list of resources Example:

apiVersion: v1
kind: Service
metadata:
  name: redis-svc
  namespace: default
spec:
  type: ClusterIP
  selector:
    app: redis
    role: logstore
  ports:
  - name: redis-port
    port: 6373
    targetPort: 6379

Run View:

kubectl apply -f svc- demo.yaml
kubectl get svc

The results are shown:

 

Resource record parsing name format: SVC_NAME.NS_NAME.DOMAIN.LTD.

Such as the above named redis: redis.default.svc.cluster.local.

When we type using NodePort time, you can at ports configured inside nodePort parameters (more than 30,000 ports, do not specify the random).

Be sure that the port is useless to another service.

When we only CluterIP to None, the resource record resolves directly to the Pod. At this time, when re-use dig added resolved locally, the resource record needs to resolve the IP address of kube-dns.