So what is your issue, you should write a docker-compose file so you will have a signe instance of posgresql but some container will share volume. Do you have some issues?

version: '3.1'
services:
  web1:
    image: odoo:16.0
    depends_on:
      - db
    ports:
      - "8070:8069"
    volumes:
      - odoo-web-data/web1:/var/lib/odoo
      - ./config/web1:/etc/odoo
      - ./addons/web1:/mnt/extra-addons
    environment:
      - PASSWORD_FILE=/run/secrets/postgresql_password
    secrets:
      - postgresql_password
web2:
    image: odoo:16.0
    depends_on:
      - db
    ports:
      - "8069:8069"
    volumes:
      - odoo-web-data/web2:/var/lib/odoo
      - ./config/web2:/etc/odoo
      - ./addons/web2:/mnt/extra-addons
    environment:
      - PASSWORD_FILE=/run/secrets/postgresql_password
    secrets:
      - postgresql_password
  db:
    image: postgres:15
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_PASSWORD_FILE=/run/secrets/postgresql_password
      - POSTGRES_USER=odoo
      - PGDATA=/var/lib/postgresql/data/pgdata
    volumes:
      - odoo-db-data:/var/lib/postgresql/data/pgdata
    secrets:
      - postgresql_password
volumes:
  odoo-web-data:
  odoo-db-data:

secrets:
  postgresql_password:
    file: odoo_pg_pass

Hi,

Please go through our below blogs to know idea about how to deploy odoo using Docker

How to Deploy Odoo 15 Using Docker

How to Install Odoo 16 in Docker?

Hope it helps