update config.py, database.py, env.py to support deploy to Render

Author: osanto

alembic/env.py

@@ -10,10 +10,19 @@
 # this is the Alembic Config object, which provides
 # access to the values within the .ini file in use.
 config = context.config
-config.set_main_option(
-    "sqlalchemy.url",
-    f"postgresql+psycopg2://{settings.database_username}:{settings.database_password}@{settings.database_hostname}:{settings.database_port}/{settings.database_name}",
-)
+
+if settings.database_url:
+    sqlalchemy_url = settings.database_url
+else:
+    sqlalchemy_url = (
+        f"postgresql+psycopg2://{settings.database_username}:"
+        f"{settings.database_password}@"
+        f"{settings.database_hostname}:"
+        f"{settings.database_port}/"
+        f"{settings.database_name}"
+    )
+
+config.set_main_option("sqlalchemy.url", sqlalchemy_url)
 
 # Interpret the config file for Python logging.
 # This line sets up loggers basically.

app/config.py

@@ -1,13 +1,19 @@
 import os
 from pydantic_settings import BaseSettings
+from typing import Optional
 
 
 class Settings(BaseSettings):
-    database_username: str
-    database_password: str
-    database_hostname: str
-    database_port: str
-    database_name: str
+    # Render / production
+    database_url: Optional[str] = None
+
+    # Local / docker (optional)
+    database_username: Optional[str] = None
+    database_password: Optional[str] = None
+    database_hostname: Optional[str] = None
+    database_port: Optional[str] = None
+    database_name: Optional[str] = None
+
     secret_key: str
     algorithm: str
     access_token_expire_minutes: int

app/database.py

@@ -3,9 +3,21 @@
 from sqlalchemy.orm import sessionmaker
 from .config import settings
 
-SQLALCHEMY_DATABASE_URL = f"postgresql://{settings.database_username}:{settings.database_password}@{settings.database_hostname}:{settings.database_port}/{settings.database_name}"
+if settings.database_url:
+    DATABASE_URL = settings.database_url
+else:
+    DATABASE_URL = (
+        f"postgresql://{settings.database_username}:"
+        f"{settings.database_password}@"
+        f"{settings.database_hostname}:"
+        f"{settings.database_port}/"
+        f"{settings.database_name}"
+    )
 
-engine = create_engine(SQLALCHEMY_DATABASE_URL)
+if not DATABASE_URL:
+    raise RuntimeError("Database configuration is missing")
+
+engine = create_engine(DATABASE_URL)
 
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)