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I'm struggling with Kubernetes' service without a selector. The cluster is installed on AWS with the kops. I have a deployment with 3 nginx pods exposing port 80:
apiVersion: apps/v1
kind: Deployment
metadata:
name: ngix-dpl # Name of the deployment object
labels:
app: nginx
spec:
replicas: 3 # Number of instances in the deployment
selector: # Selector identifies pods to be
matchLabels: # part of the deployment
app: nginx # by matching of the label "app"
template: # Templates describes pods of the deployment
metadata:
labels: # Defines key-value map
app: nginx # Label to be recognized by other objects
spec: # as deployment or service
containers: # Lists all containers in the pod
- name: nginx-pod # container name
image: nginx:1.17.4 # container docker image
ports:
- containerPort: 80 # port exposed by container
After creation of the deployment, I noted the IP addresses:
$ kubectl get pods -o wide | awk {'print $1" " $3" " $6'} | column -t
NAME STATUS IP
curl Running 100.96.6.40
ngix-dpl-7d6b8c8944-8zsgk Running 100.96.8.53
ngix-dpl-7d6b8c8944-l4gwk Running 100.96.6.43
ngix-dpl-7d6b8c8944-pffsg Running 100.96.8.54
and created a service that should serve the IP addresses:
apiVersion: v1
kind: Service
metadata:
name: dummy-svc
labels:
app: nginx
spec:
ports:
- protocol: TCP
port: 80
targetPort: 80
---
apiVersion: v1
kind: Endpoints
metadata:
name: dummy-svc
subsets:
- addresses:
- ip: 100.96.8.53
- ip: 100.96.6.43
- ip: 100.96.8.54
ports:
- port: 80
name: http
The service is successfully created:
$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
dummy-svc ClusterIP 100.64.222.220 <none> 80/TCP 32m
kubernetes ClusterIP 100.64.0.1 <none> 443/TCP 5d14h
Unfortunately, my attempt to connect to the nginx through the service from another pod of the same namespace fails:
$ curl 100.64.222.220
curl: (7) Failed to connect to 100.64.222.220 port 80: Connection refused
I can successfully connect to the nginx pods directly:
$ curl 100.96.8.53
<!DOCTYPE html>
<html>
<head>
....
I noticed that my service does not have any endpoints. But I'm not sure that the manual endpoints should be shown there:
$ kubectl get svc/dummy-svc -o yaml
apiVersion: v1
kind: Service
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"nginx"},"name":"dummy-svc","namespace":"default"},"spec":{"ports":[{"port":80,"protocol":"TCP","targetPort":80}]}}
creationTimestamp: "2019-11-22T08:41:29Z"
labels:
app: nginx
name: dummy-svc
namespace: default
resourceVersion: "4406151"
selfLink: /api/v1/namespaces/default/services/dummy-svc
uid: e0aa9d01-0d03-11ea-a19c-0a7942f17bf8
spec:
clusterIP: 100.64.222.220
ports:
- port: 80
protocol: TCP
targetPort: 80
sessionAffinity: None
type: ClusterIP
status:
loadBalancer: {}
I understand that it is not a proper use case for services and using of a pod selector will bring it to work. But I want to understend why this configuration does not work. I don't know where to look for the solution. Any hint will be appreciated.
correct the service definition as below
it works if you remove the "name" field from the endpoints configuration. it should look like this: