无法从Go Web服务器连接到kubernetes集群中的Postgres StatefulSet

Question

我在 Golang 中有一个 Web 服务器，它作为 StatefulSet 连接到 Postgres。但是，我在连接时遇到错误，没有找到这样的主机。 Web 服务器是使用 ClusterIP 作为网络服务和用于创建 Pod 的部署来创建的。 Postgres 是使用 Headless Service 和 StatefulSet 创建的。以下是我的k8s配置文件以及错误信息：

# headless-service.yml
apiVersion: v1
kind: Service
metadata:
  name: authentication-headless-service
  labels:
    ims: authentication
spec:
  clusterIP: None # headless service
  selector:
    ims: authentication-postgres
  ports:
    - name: authentication-postgres-h
      port: 5432
      targetPort: 5432

# statefulset.yml
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: authentication-postgres-statefulset
spec:
  serviceName: authentication-headless-service
  replicas: 1
  selector:
    matchLabels:
      ims: authentication-postgres
  template:
    metadata:
      labels:
        ims: authentication-postgres
    spec:
      containers:
        - name: postgres
          image: postgres:14.2
          env:
            - name: POSTGRES_USER
              valueFrom:
                secretKeyRef:
                  name: authentication-secret
                  key: POSTGRES_USER
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: authentication-secret
                  key: POSTGRES_PASSWORD
            - name: POSTGRES_HOST
              valueFrom:
                secretKeyRef:
                  name: authentication-secret
                  key: POSTGRES_HOST
          ports:
            - containerPort: 5432
              name: postgres
          volumeMounts:
            - name: postgres-authentication-data
              mountPath: /var/lib/postgresql/data
              subPath: postgres # specific to postgres
          livenessProbe:
            tcpSocket:
              port: 5432
            initialDelaySeconds: 60
            periodSeconds: 30
            failureThreshold: 3
          readinessProbe:
            tcpSocket:
              port: 5432
            initialDelaySeconds: 60
            periodSeconds: 30
            failureThreshold: 3
  volumeClaimTemplates:
    - metadata:
        name: postgres-authentication-data
      spec:
        accessModes:
          - "ReadWriteOnce"
        resources:
          requests:
            storage: 500Mi
        storageClassName: ims-storage-class

apiVersion: v1
kind: Secret
metadata:
  name: authentication-secret
type: Opaque
data:
  POSTGRES_USER: YXV0aGVudGljYXRpb24tcG9zdGdyZXM=
  POSTGRES_PASSWORD: cGFzc3dvcmQ=

  # base64 encoded 'authentication-postgres-0.authentication-headless-service.default.svc.cluster.local'
  POSTGRES_HOST: YXV0aGVudGljYXRpb24tcG9zdGdyZXMtMC5hdXRoZW50aWNhdGlvbi1oZWFkbGVzcy1zZXJ2aWNlLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWw=

---
apiVersion: v1
kind: Service
metadata:
  name: authentication-clusterip
spec:
  type: ClusterIP
  ports:
    - targetPort: 8001
      port: 8001
  selector:
    ims: authentication

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: authentication-deployment
  namespace: default
spec:
  replicas: 4
  selector:
    matchLabels:
      ims: authentication
  template:
    metadata:
      labels:
        ims: authentication
    spec:
      containers:
        - name: authentication
          image: localhost:5050/ims-authentication:latest
          ports:
            - containerPort: 8001
          env:
            - name: MODE
              value: docker
            - name: POSTGRES_USER
              valueFrom:
                secretKeyRef:
                  name: authentication-secret
                  key: POSTGRES_USER
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: authentication-secret
                  key: POSTGRES_PASSWORD
            - name: POSTGRES_HOST
              valueFrom:
                secretKeyRef:
                  name: authentication-secret
                  key: POSTGRES_HOST
            - name: POSTGRES_PORT
              valueFrom:
                configMapKeyRef:
                  name: authentication-configmap
                  key: POSTGRES_PORT
            - name: POSTGRES_DB
              valueFrom:
                configMapKeyRef:
                  name: authentication-configmap
                  key: POSTGRES_DB
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0

这是错误消息：

kubectl logs authentication-deployment-99c845645-vr48p

2024/09/18 17:16:10 failed to connect to postgres db: failed to connect to `user=authentication-postgres database=imsdb`: hostname resolving error: lookup authentication-postgres-0.authentication-headless-service.default.svc.cluster.local on 10.96.0.10:53: no such host

Answer 1

我注意到

$.metadata.namespace

仅指定为

default

部署的

authentication-deployment

，而不是 StatefulSet 或服务。请验证所有资源都是在同一命名空间中创建的，可以直接在 YAML 中指定，也可以通过

kubectl

和

-n <namespace>

。否则，DNS 记录将无法按预期解析，因为它们的构建方式类似于

<name>.<namespace>.svc.cluster.local

。