docker-compose.yaml

services:
  pg_primary:
    image: postgres:16
    user: postgres
    restart: always
    healthcheck:
      test: 'pg_isready -U user --dbname=postgres'
      interval: 10s
      timeout: 5s
      retries: 5
    ports:
      - 5432:5432
    environment:
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password
      POSTGRES_HOST_AUTH_METHOD: "scram-sha-256\nhost replication all 0.0.0.0/0 md5"
      POSTGRES_INITDB_ARGS: "--auth-host=scram-sha-256"
    command: |
      postgres
      -c wal_level=replica
      -c hot_standby=on
      -c max_wal_senders=10
      -c max_replication_slots=10
      -c hot_standby_feedback=on
    volumes:
      - ${PWD}/00_init.sql:/docker-entrypoint-initdb.d/00_init.sql:ro

  pg_replica:
    image: postgres:16
    user: postgres
    restart: always
    healthcheck:
      test: 'pg_isready -U user --dbname=postgres'
      interval: 10s
      timeout: 5s
      retries: 5
    ports:
      - 5433:5432
    environment:
      PGUSER: replicator
      PGPASSWORD: replicator_password
    command: |
      bash -c "
      until pg_basebackup --pgdata=/var/lib/postgresql/data -R --slot=replication_slot --host=pg_primary --port=5432
      do
      echo 'Waiting for primary to connect..'
      sleep 1s
      done
      echo 'Backup done, starting replica...'
      chmod 0700 /var/lib/postgresql/data
      postgres
      "
    depends_on:
      - pg_primary