Services map a port on each cluster node to ports on one or more pods.
The mapping uses a selector key:value pair in the service, and the
labels property of pods. Any pods whose labels match the service selector
are made accessible through the service’s port.
For more information, see the Services Overview.
Create a service
Services are created by passing a configuration file to the kubectl create
command:
$ kubectl create -f FILE
Where:
-f FILEor--filename FILEis a relative path to a service configuration file in either JSON or YAML format.
A successful service create request returns the service name. You can use a sample file below to try a create request.
Service configuration file
When creating a service, you must point to a service configuration file as the
value of the -f flag. The configuration file can be formatted as
YAML or as JSON, and supports the following fields:
{
"kind": "Service",
"apiVersion": "v1",
"metadata": {
"name": string
},
"spec": {
"ports": [{
"port": int,
"targetPort": int
}],
"selector": {
string: string
},
"type": "LoadBalancer",
"loadBalancerSourceRanges": [
"10.180.0.0/16",
"10.245.0.0/24"
]
}
}
Required fields are:
kind: AlwaysService.apiVersion: Currentlyv1.metadata: Contains:name: The name to give to this service.
spec: Contains:ports: The ports to map.portis the service port to expose on the cluster IP.targetPortis the port to target on the pods that are part of this service.selector: The label key:value pair that defines the pods to target.type: Optional. If the type isLoadBalancer, sets up a network load balancer for your service. This provides an externally-accessible IP address that sends traffic to the correct port on your cluster nodes.loadBalancerSourceRanges:: Optional. Must use withLoadBalancertype. If specified and supported by the cloud provider, this will restrict traffic such that the load balancer will be accessible only to clients from the specified IP ranges. This field will be ignored if the cloud-provider does not support the feature.
For the full service schema see the
Kubernetes api reference.
Sample files
The following service configuration files assume that you have a set of pods
that expose port 9376 and carry the label app=example.
Both files create a new service named myapp which resolves to TCP port 9376
on any pod with the app=example label.
The difference in the files is in how the service is accessed. The first file does not create an external load balancer; the service can be accessed through port 8765 on any of the nodes’ IP addresses.
service-sample.json |
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service-sample.yaml |
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The second file uses
network load balancing to create a
single IP address that spreads traffic to all of the nodes in
your cluster. This option is specified with the
"type": "LoadBalancer" property.
load-balancer-sample.json |
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load-balancer-sample.yaml |
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To access the service, a client connects to the external IP address, which forwards to port 8765 on a node in the cluster, which in turn accesses port 9376 on the pod. See the Service configuration file section of this doc for directions on finding the external IP address.
View a service
To list all services on a cluster, use the
kubectl get command:
$ kubectl get services
A successful get request returns all services that exist on the specified cluster:
NAME LABELS SELECTOR IP PORT
myapp <none> app=MyApp 10.123.255.83 8765/TCP
To return information about a specific service, use the
kubectl describe command:
$ kubectl describe service NAME
Details about the specific service are returned:
Name: myapp
Labels: <none>
Selector: app=MyApp
IP: 10.123.255.83
Port: <unnamed> 8765/TCP
NodePort: <unnamed> 31474/TCP
Endpoints: <none>
Session Affinity: None
No events.
To return information about a service when event information is not required,
substitute get for describe.
Delete a service
To delete a service, use the kubectl delete command:
$ kubectl delete service NAME
A successful delete request returns the deleted service’s name.