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How To Create A Multi Layer Docker Compose

Introduction​

Many projects need to support multiple environments or configurations (like Oracle vs. Postgres, local vs. CI, dev vs. prod).

In this article we are going to explore using multiple compose files layered together. This is the most common and recommended approach.

You keep a base docker-compose.yml that defines the shared services (e.g., app, API, etc.) and then create override files for database-specific configuration.

Example file structure:

  • docker-compose.yml
  • docker-compose.oracle.yml
  • docker-compose.postgres.yml

Base file (docker-compose.yml):​

version: '3.9'
services:
  app:
    build: .
    environment:
      - DB_CONNECTION_STRING=${DB_CONNECTION_STRING}
    depends_on:
      - db

Oracle override (docker-compose.oracle.yml):​

services:
  db:
    image: oracleinanutshell/oracle-xe-11g
    environment:
      - ORACLE_PASSWORD=oracle
    ports:
      - "1521:1521"

  app:
    environment:
      - DB_CONNECTION_STRING=User Id=system;Password=oracle;Data Source=oracle:1521/XE;

Postgres override (docker-compose.postgres.yml):​

services:
  db:
    image: postgres:15
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
      - POSTGRES_DB=labdb
    ports:
      - "5432:5432"

  app:
    environment:
      - DB_CONNECTION_STRING=Host=postgres;Port=5432;Database=labdb;Username=postgres;Password=postgres;

Usage​

Start Oracle setup​

docker compose -f docker-compose.yml -f docker-compose.oracle.yml up -d

Start Postgres setup

docker compose -f docker-compose.yml -f docker-compose.postgres.yml up -d

💡 You can also define COMPOSE_FILE in a .env file:

COMPOSE_FILE=docker-compose.yml:docker-compose.oracle.yml

and switch it dynamically by changing that variable.

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