"Kubernetes：无法从 Kubernetes 集群外部连接到 postgres"

Question

I've launched a postgresql server in minikube, and I'm having difficulty connecting to it from outside the cluster.

---

kubectl --context=minikube create -f postgres-statefulset.yaml
kubectl --context=minikube create -f postgres-service.yaml

url=$(minikube service postgres --url --format={{.IP}}:{{.Port}})

psql --host=${url%:*} --port=${url#*:} --username=postgres --dbname=postgres \
     --command='SELECT refobjid FROM pg_depend LIMIT 1'
Password for user postgres:
 refobjid
----------
     1247

Answer 1

I just deployed postgres and exposed its service through NodePort and following is my pod and service.

[root@master postgres]# kubectl get pods
NAME                        READY     STATUS    RESTARTS   AGE
postgres-7ff9df5765-2mpsl   1/1       Running   0          1m

[root@master postgres]# kubectl get svc postgres
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
postgres     NodePort    10.100.199.212   <none>        5432:31768/TCP   20s

And this is how connected to postgres though the nodeport:

[root@master postgres]# kubectl exec -it postgres-7ff9df5765-2mpsl --  psql -h 10.6.35.83 -U postgresadmin --password -p 31768 postgresdb
Password for user postgresadmin: 
psql (10.4 (Debian 10.4-2.pgdg90+1))
Type "help" for help.

postgresdb=# 

In above, 10.6.35.83 is my node/host IP (not pod IP or clusterIP) and port is the NodePort defined in service. The issue is you're not using the right IP to connect to the postgresql.

Answer 2

To be able to correctly translate outside packets inside of the postgres container, you have to explicitly define listen_address=0.0.0.0 config parameter.

This can be done through the command line options:

Look at this sample deployment config:

deployment.yaml

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-postgres-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: {{ .Release.Name }}-postgres
  template:
    metadata:
      labels:
        app: {{ .Release.Name }}-postgres
    spec:
      containers:
      - name: postgres
        image: postgres
        args: ["-d", "postgres", "-c", "listen_addresses=0.0.0.0"]
        env:
          - name: "POSTGRES_PASSWORD"
            value: "postgres"
        ports:
        - containerPort: 5432

service.yaml

---
apiVersion: v1
kind: Service
metadata:
  name: {{ .Release.Name }}-postgres-service
spec:
  type: {{ .Values.serviceType | default "ClusterIP" }}
  selector:
    app: {{ .Release.Name }}-postgres
  ports:
    - protocol: TCP
      port: 5432

That's really all you need to run your test container with postgresql in k8s.

Answer 3

I had this challenge when working with PostgreSQL<\/strong> database server in Kubernetes<\/strong> using minikube<\/strong> .

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: postgresql-db
spec:
  serviceName: postgresql-db-service
  replicas: 2
  selector:
    matchLabels:
      app: postgresql-db
  template:
    metadata:
      labels:
        app: postgresql-db
    spec:
      containers:
      - name: postgresql-db
        image: postgres:latest
        ports:
        - containerPort: 5432
          name: postgresql-db
        volumeMounts:
        - name: postgresql-db-data
          mountPath: /data
        env:
          - name: POSTGRES_PASSWORD
            valueFrom:
              secretKeyRef:
                name: postgresql-db-secret
                key: DATABASE_PASSWORD
          - name: PGDATA
            valueFrom:
              configMapKeyRef:
                name: postgresql-db-configmap
                key: PGDATA
  volumeClaimTemplates:
  - metadata:
      name: postgresql-db-data
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 25Gi