如何获取statefulset无头服务的SRV DNS地址

Question

kind: List
apiVersion: v1
items:
- apiVersion: v1
  kind: Service
  metadata:
    name: sfs-svc
    labels:
      app: sfs-app
  spec:
    ports:
    - port: 80
      name: web
    clusterIP: None
    selector:
      app: sfs-app
- apiVersion: apps/v1
  kind: StatefulSet
  metadata:
    name: web
  spec:
    selector:
      matchLabels:
        app: sfs-app # has to match .spec.template.metadata.labels
    serviceName: "sfs-svc"
    replicas: 3 
    template:
      metadata:
        labels:
          app: sfs-app # has to match .spec.selector.matchLabels
      spec:
        terminationGracePeriodSeconds: 10
        containers:
        - name: test-container
          image: nginx
          imagePullPolicy: IfNotPresent
          command: [ "sh", "-c"]
          args:
          - while true; do
              printenv MY_NODE_NAME MY_POD_NAME MY_POD_NAMESPACE >> /var/sl/output.txt;
              printenv MY_POD_IP >> /var/sl/output.txt;
              date >> var/sl/output.txt; 
              cat /var/sl/output.txt;
              sleep 999999;
            done;
          env:
            - name: MY_NODE_NAME
              valueFrom:
                fieldRef:
                  fieldPath: spec.nodeName
            - name: MY_POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
            - name: MY_POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
            - name: MY_POD_IP
              valueFrom:
                fieldRef:
                  fieldPath: status.podIP
          volumeMounts:
          - name: www
            mountPath: /var/sl
    volumeClaimTemplates:
    - metadata:
        name: www
      spec:
        accessModes: [ "ReadWriteOnce" ]
        #storageClassName: classNameIfAny
        resources:
          requests:
            storage: 1Mi

$kubectl版本

客户端版本：Version.info{Major：“1”,Minor：“13”,GitVersion：“V1.13.3”,GitCommit：“721BFA751924DA8D1680787490C54B9179B1FED0”,GitTreEstate：“Clean”,BuildDate：“2019-02-01T20:08:12Z”,GoVersion：“Go1.11.5”,编译器：“GC”,平台：“Linux/AMD64”}服务器版本：Version.info{Major：“1”,Minor：“14”,GitVersion：“V1.14.1”,GitCommit：“B7394102D6EF778017F2CA4046ABBAA23 B88C290”,GitTreeState：“Clean”,BuildDate：“2019-04-08T17:02:58Z”,GoVersion：“Go1.12.1”,编译器：“GC”,平台：“Linux/AMD64”}

$kubectl获取po、svc、statefulset

> NAME        READY   STATUS    RESTARTS   AGE
> pod/web-0   1/1     Running   0          45m
> pod/web-1   1/1     Running   0          45m
> pod/web-2   1/1     Running   0          45m
> 
> NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
> service/kubernetes   ClusterIP   10.96.0.1    <none>        443/TCP   46m
> service/sfs-svc      ClusterIP   None         <none>        80/TCP    45m
> 
> NAME                   READY   AGE
> statefulset.apps/web   3/3     45m
> 

当我尝试$nslookup sfs-svc.default.svc.cluster.local时

> Server:       127.0.0.53
> Address:  127.0.0.53#53
> 
**> ** server can't find sfs-svc.default.svc.cluster.local: SERVFAIL**
> 

Answer 1

我的第一个猜测是，您正在从localhost而不是从pod内部运行nslookup。

我尝试了yaml，只能在从localhost运行nslookup sfs-svc.default.svc.cluster.local时重新生成此问题。

无论如何，要检查服务的DNS条目，请从POD内部运行nslookup。这里有一个例子,

~ $ kubectl run -it --rm --restart=Never dnsutils2 --image=tutum/dnsutils  --command -- bash

root@dnsutils2:/# nslookup sfs-svc.default.svc.cluster.local
Server:     10.96.0.10
Address:    10.96.0.10#53

Name:   sfs-svc.default.svc.cluster.local
Address: 172.17.0.6
Name:   sfs-svc.default.svc.cluster.local
Address: 172.17.0.5
Name:   sfs-svc.default.svc.cluster.local
Address: 172.17.0.4

root@dnsutils2:/# exit