gushcloud/postgresql-client

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postgresql-client

Postgresql client for init containers in Kubernetes

Github: https://github.com/gushai-platform/postgresql-client

shell
docker pull gushcloud/postgresql-client:latest

Kubernetes wait for a database to be ready with init containers

In Kubernetes, if your app depends on a database, it is a good idea to check that the database is ready before spinning up the application. This can be done using init containers which fires off before containers start to run. The init containers need to complete before containers can start. This is particularly important when there is an upgrade or a node change in Kubernetes where services can spin up faster than the database.

Example deployment yaml

Sleep for 2 seconds and try again until database service is running.

yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: app
    spec:
      initContainers:
      - name: check-db-ready
        image: gushcloud/postgresql-client:latest
        command: ['sh', '-c', 'until pg_isready -h postgresql-service -p 5432; do echo waiting for database; sleep 2; done;']
      containers:
      - image: busybox
        name: busybox
        ports:
        - containerPort: 3000
        env:
        - name: postgresql_host
          value: postgresql-service
        - name: postgresql_port
          value: "5432"
        - name: postgresql_user
          valueFrom:
            secretKeyRef:
              name: database-secret
              key: user
        - name: postgresql_database
          valueFrom:
            secretKeyRef:
              name: database-secret
              key: database
        - name: postgresql_password
          valueFrom:
            secretKeyRef:
              name: database-secret
              key: password