♻️ Refactor env vars handling

Author: tiangolo

.env

@@ -14,10 +14,5 @@ SMTP_TLS=False
 SMTP_PORT=1025
 
 # Postgres
-POSTGRES_SERVER=localhost
-POSTGRES_DB=app
-POSTGRES_USER=postgres
 POSTGRES_PASSWORD=changethis
-
-# Database URL for the backend (uses localhost for local dev, overridden in compose.yml for Docker)
-DATABASE_URL=postgresql+psycopg://postgres:changethis@localhost:5432/app
+DATABASE_URL=postgresql://postgres:${POSTGRES_PASSWORD}@localhost:5432/app

backend/app/core/config.py

@@ -6,6 +6,7 @@
     HttpUrl,
     PostgresDsn,
     computed_field,
+    field_validator,
     model_validator,
 )
 from pydantic_settings import BaseSettings, SettingsConfigDict
@@ -29,6 +30,15 @@ class Settings(BaseSettings):
     SENTRY_DSN: HttpUrl | None = None
     DATABASE_URL: PostgresDsn
 
+    @field_validator("DATABASE_URL", mode="before")
+    @classmethod
+    def _use_psycopg_driver(cls, value: str | PostgresDsn) -> str:
+        database_url = str(value)
+        for scheme in ("postgres://", "postgresql://"):
+            if database_url.startswith(scheme):
+                return database_url.replace(scheme, "postgresql+psycopg://", 1)
+        return database_url
+
     SMTP_TLS: bool = True
     SMTP_SSL: bool = False
     SMTP_PORT: int = 587
@@ -69,6 +79,8 @@ def _check_default_secret(self, var_name: str, value: str | None) -> None:
     @model_validator(mode="after")
     def _enforce_non_default_secrets(self) -> Self:
         self._check_default_secret("SECRET_KEY", self.SECRET_KEY)
+        for host in self.DATABASE_URL.hosts():
+            self._check_default_secret("DATABASE_URL password", host["password"])
         self._check_default_secret(
             "FIRST_SUPERUSER_PASSWORD", self.FIRST_SUPERUSER_PASSWORD
         )

compose.yml

@@ -20,7 +20,7 @@ services:
   db:
     image: postgres:18
     healthcheck:
-      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_USER} -d ${POSTGRES_DB}"]
+      test: ["CMD-SHELL", "pg_isready -U postgres -d app"]
       interval: 10s
       retries: 5
       start_period: 30s
@@ -29,8 +29,7 @@ services:
       - app-db-data:/var/lib/postgresql
     environment:
       - POSTGRES_PASSWORD=${POSTGRES_PASSWORD:?Variable not set}
-      - POSTGRES_USER=${POSTGRES_USER:?Variable not set}
-      - POSTGRES_DB=${POSTGRES_DB:?Variable not set}
+      - POSTGRES_DB=app
 
   adminer:
     image: adminer
@@ -62,11 +61,7 @@ services:
       SMTP_USER: ${SMTP_USER:-}
       SMTP_PASSWORD: ${SMTP_PASSWORD:-}
       EMAILS_FROM_EMAIL: ${EMAILS_FROM_EMAIL}
-      POSTGRES_SERVER: db
-      POSTGRES_DB: ${POSTGRES_DB:?Variable not set}
-      POSTGRES_USER: ${POSTGRES_USER:?Variable not set}
-      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?Variable not set}
-      DATABASE_URL: postgresql+psycopg://${POSTGRES_USER:?Variable not set}:${POSTGRES_PASSWORD:?Variable not set}@db:${POSTGRES_PORT:-5432}/${POSTGRES_DB}
+      DATABASE_URL: postgresql://postgres:${POSTGRES_PASSWORD:?Variable not set}@db:5432/app
       SENTRY_DSN: ${SENTRY_DSN:-}
 
     healthcheck:

deployment.md

@@ -80,8 +80,6 @@ You can set several other environment variables:
 * `SMTP_USER`: The SMTP server user to send emails.
 * `SMTP_PASSWORD`: The SMTP server password to send emails.
 * `EMAILS_FROM_EMAIL`: The email account to send emails from.
-* `POSTGRES_USER`: The Postgres user, you can leave the default.
-* `POSTGRES_DB`: The database name to use for this application. You can leave the default of `app`.
 * `SENTRY_DSN`: The DSN for Sentry, if you are using it.
 
 ## GitHub Actions Environment Variables