3/3

Environment Variables & Configuration

+15 XP on completion

#Environment Variables & Configuration

After this lesson you'll know:

how to manage env vars safely
env_file vs environment
profiles for different setups

#Three ways to set env vars

services:
  api:
    # 1. Directly in YAML
    environment:
      DEBUG: "true"
      NODE_ENV: production

    # 2. From a file
    env_file: .env.production

    # 3. From the host machine
    environment:
      - SECRET_KEY  # Gets the value from the host environment

#env_file

# .env (automatically loaded by compose)
POSTGRES_PASSWORD=***
POSTGRES_USER=app

# .env.production (specified manually)
NODE_ENV=production
API_PORT=3000

#Profiles

With profiles you can define different setups for dev and prod:

services:
  api:
    image: my-api
    profiles: ["dev", "prod"]

  mailpit:
    image: axllent/mailpit
    profiles: ["dev"]  # Dev only

  prometheus:
    image: prom/prometheus
    profiles: ["prod"]  # Prod only

# Dev services only
docker compose --profile dev up -d

# Prod services only
docker compose --profile prod up -d

#✋ Try it out

Create a compose.yml with two profiles: dev (web + db) and prod (web + db + redis). Start only dev with --profile dev
Create a .env file with POSTGRES_PASSWORD and use ${POSTGRES_PASSWORD} in your compose.yml

#📌 Summary

Three ways for env vars: environment directly, env_file, or host variables
Profiles allow different setups for dev and prod
The .env file is automatically loaded by Compose

Compose Challenge

Test your knowledge with a quick quiz!

4 questions · +40 XP

← → to navigate