♻️ Require non-empty Compose configuration (#2418)

## AI Disclaimer

Using Codex with gpt-5.6-sol. Reviewed manually.

.env

@@ -1,10 +1,3 @@
-# Domain
-# This would be set to the production domain with an env var on deployment
-# used by Traefik to transmit traffic and acquire TLS certificates
-DOMAIN=localhost
-# To test the local Traefik config
-# DOMAIN=localhost.tiangolo.com
-
 # Environment: local, staging, production
 ENVIRONMENT=local
 

compose.deploy.yml

@@ -38,7 +38,7 @@ services:
     restart: always
     labels:
       # Route HTTPS traffic for the Adminer subdomain
-      - traefik.http.routers.adminer-https.rule=Host(`adminer.${DOMAIN?Variable not set}`)
+      - traefik.http.routers.adminer-https.rule=Host(`adminer.${DOMAIN:?Variable not set}`)
       - traefik.http.routers.adminer-https.entrypoints=https
       - traefik.http.routers.adminer-https.tls=true
       # Use the Let's Encrypt resolver
@@ -46,15 +46,15 @@ services:
 
   prestart:
     environment:
-      FRONTEND_HOST: https://${DOMAIN?Variable not set}
+      FRONTEND_HOST: https://${DOMAIN:?Variable not set}
 
   backend:
     restart: always
     environment:
-      FRONTEND_HOST: https://${DOMAIN?Variable not set}
+      FRONTEND_HOST: https://${DOMAIN:?Variable not set}
     labels:
       # Route HTTPS traffic for this domain
-      - traefik.http.routers.backend-https.rule=Host(`${DOMAIN?Variable not set}`)
+      - traefik.http.routers.backend-https.rule=Host(`${DOMAIN:?Variable not set}`)
       - traefik.http.routers.backend-https.entrypoints=https
       - traefik.http.routers.backend-https.tls=true
       # Use the Let's Encrypt resolver

compose.override.yml

@@ -94,8 +94,8 @@ services:
       - backend
       - mailcatcher
     environment:
-      - FIRST_SUPERUSER=${FIRST_SUPERUSER?Variable not set}
-      - FIRST_SUPERUSER_PASSWORD=${FIRST_SUPERUSER_PASSWORD?Variable not set}
+      - FIRST_SUPERUSER=${FIRST_SUPERUSER:?Variable not set}
+      - FIRST_SUPERUSER_PASSWORD=${FIRST_SUPERUSER_PASSWORD:?Variable not set}
       - PLAYWRIGHT_BASE_URL=http://backend:8000
       - VITE_API_URL=http://backend:8000
       - MAILCATCHER_HOST=http://mailcatcher:1080

compose.yml

@@ -28,9 +28,9 @@ services:
     volumes:
       - app-db-data:/var/lib/postgresql
     environment:
-      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD?Variable not set}
-      - POSTGRES_USER=${POSTGRES_USER?Variable not set}
-      - POSTGRES_DB=${POSTGRES_DB?Variable not set}
+      - POSTGRES_PASSWORD=${POSTGRES_PASSWORD:?Variable not set}
+      - POSTGRES_USER=${POSTGRES_USER:?Variable not set}
+      - POSTGRES_DB=${POSTGRES_DB:?Variable not set}
 
   adminer:
     image: adminer
@@ -42,7 +42,7 @@ services:
       # Enable Traefik for this service
       - traefik.enable=true
       # Route HTTP traffic for the Adminer subdomain
-      - traefik.http.routers.adminer-http.rule=Host(`adminer.${DOMAIN?Variable not set}`)
+      - traefik.http.routers.adminer-http.rule=Host(`adminer.${DOMAIN:-localhost}`)
       - traefik.http.routers.adminer-http.entrypoints=http
       # Define the port inside of the Docker service to use
       - traefik.http.services.adminer.loadbalancer.server.port=8080
@@ -57,19 +57,19 @@ services:
         condition: service_completed_successfully
     # The YAML anchor lets the prestart service reuse this environment mapping.
     environment: &backend-environment
-      PROJECT_NAME: ${PROJECT_NAME?Variable not set}
+      PROJECT_NAME: ${PROJECT_NAME:?Variable not set}
       BACKEND_CORS_ORIGINS: ${BACKEND_CORS_ORIGINS:-}
-      SECRET_KEY: ${SECRET_KEY?Variable not set}
-      FIRST_SUPERUSER: ${FIRST_SUPERUSER?Variable not set}
-      FIRST_SUPERUSER_PASSWORD: ${FIRST_SUPERUSER_PASSWORD?Variable not set}
+      SECRET_KEY: ${SECRET_KEY:?Variable not set}
+      FIRST_SUPERUSER: ${FIRST_SUPERUSER:?Variable not set}
+      FIRST_SUPERUSER_PASSWORD: ${FIRST_SUPERUSER_PASSWORD:?Variable not set}
       SMTP_HOST: ${SMTP_HOST}
       SMTP_USER: ${SMTP_USER:-}
       SMTP_PASSWORD: ${SMTP_PASSWORD:-}
       EMAILS_FROM_EMAIL: ${EMAILS_FROM_EMAIL}
       POSTGRES_SERVER: db
-      POSTGRES_DB: ${POSTGRES_DB}
-      POSTGRES_USER: ${POSTGRES_USER?Variable not set}
-      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD?Variable not set}
+      POSTGRES_DB: ${POSTGRES_DB:?Variable not set}
+      POSTGRES_USER: ${POSTGRES_USER:?Variable not set}
+      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?Variable not set}
       SENTRY_DSN: ${SENTRY_DSN:-}
 
     healthcheck:
@@ -89,7 +89,7 @@ services:
       - traefik.http.services.backend.loadbalancer.server.port=8000
 
       # Route HTTP traffic for this domain
-      - traefik.http.routers.backend-http.rule=Host(`${DOMAIN?Variable not set}`)
+      - traefik.http.routers.backend-http.rule=Host(`${DOMAIN:-localhost}`)
       - traefik.http.routers.backend-http.entrypoints=http
 
   prestart:

deployment.md

@@ -46,7 +46,7 @@ Copy the content and use that as password / secret key. And run that again to ge
 
 ### Required Environment Variables
 
-Set the `DOMAIN`, by default `localhost` (for development), but when deploying you would use your own domain, for example:
+Set the `DOMAIN` to your own domain, for example:
 
 ```bash
 export DOMAIN=fastapi-project.example.com