start project

app/config.py

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+"""Environment-sourced configuration classes (12-factor factor 3).
+
+Every value comes from os.environ. No secret, DB URL, or filesystem path
+is ever hardcoded; .env.example documents every variable a deployment
+must set.
+"""
+from __future__ import annotations
+
+import os
+from datetime import timedelta
+
+
+def _bool_env(name: str, default: bool = False) -> bool:
+    """Parse a boolean-ish environment variable."""
+    val = os.environ.get(name)
+    return default if val is None else val.strip().lower() in {"1", "true", "yes", "on"}
+
+
+def _engine_options_for(database_url: str) -> dict:
+    """pool_size/pool_recycle are QueuePool-only kwargs.
+
+    BUG FIX (caught by actually booting the app): SQLite's default pool
+    classes (NullPool for file DBs, StaticPool for :memory:) raise
+    TypeError if handed pool_size/pool_recycle at all — they're not
+    silently ignored. Chapter 06 makes SQLite the default engine and
+    MySQL the opt-in fallback, so these kwargs are only meaningful (and
+    only passed) when DATABASE_URL actually points at a non-SQLite engine.
+    """
+    if database_url.startswith("sqlite"):
+        return {}
+    return {
+        "pool_size": int(os.environ.get("DB_POOL_SIZE", "3")),
+        "pool_recycle": int(os.environ.get("DB_POOL_RECYCLE_SECONDS", "280")),
+        "pool_pre_ping": True,
+    }
+
+
+class BaseConfig:
+    """Shared config. Subclasses override only what differs per environment."""
+
+    SECRET_KEY: str | None = os.environ.get("SECRET_KEY")
+
+    # Chapter 06: SQLite/WAL default; swappable via DATABASE_URL without code changes.
+    SQLALCHEMY_DATABASE_URI: str = os.environ.get("DATABASE_URL", "sqlite:///kavosh.db")
+    SQLALCHEMY_ENGINE_OPTIONS: dict = _engine_options_for(SQLALCHEMY_DATABASE_URI)
+    SQLALCHEMY_TRACK_MODIFICATIONS = False
+
+    # Chapter 03: 150 max DB connections shared across up to 60 entry
+    # processes -> keep each process's pool small. Exposed as its own
+    # config key (not just buried inside SQLALCHEMY_ENGINE_OPTIONS) so
+    # budget.py can validate the *intended* setting regardless of whether
+    # the active engine (SQLite) actually consumes it.
+    DB_POOL_SIZE: int = int(os.environ.get("DB_POOL_SIZE", "3"))
+
+    # Chapter 03: filesystem cache, not Redis.
+    CACHE_TYPE = os.environ.get("CACHE_TYPE", "FileSystemCache")
+    CACHE_DIR = os.environ.get("CACHE_DIR", "/tmp/kavosh-cache")
+    CACHE_DEFAULT_TIMEOUT = int(os.environ.get("CACHE_DEFAULT_TIMEOUT", "60"))
+
+    # Chapter 12: secure session cookie flags.
+    SESSION_COOKIE_SECURE = _bool_env("SESSION_COOKIE_SECURE", True)
+    SESSION_COOKIE_HTTPONLY = True
+    SESSION_COOKIE_SAMESITE = "Lax"
+    PERMANENT_SESSION_LIFETIME = timedelta(
+        hours=int(os.environ.get("SESSION_LIFETIME_HOURS", "12"))
+    )
+
+    WTF_CSRF_ENABLED = True
+
+    # Chapter 04/12: upload constraints.
+    UPLOAD_MAX_SIZE_MB = int(os.environ.get("UPLOAD_MAX_SIZE_MB", "500"))
+    MAX_CONTENT_LENGTH = UPLOAD_MAX_SIZE_MB * 1024 * 1024
+    UPLOAD_DIR = os.environ.get("UPLOAD_DIR", "/home/kavosh/uploads")
+
+    PARSE_BATCH_SIZE = int(os.environ.get("PARSE_BATCH_SIZE", "5000"))
+    ADMIN_EMAIL = os.environ.get("ADMIN_EMAIL")
+
+
+class DevConfig(BaseConfig):
+    DEBUG = True
+    SESSION_COOKIE_SECURE = False  # allow plain-http local dev
+
+
+class ProdConfig(BaseConfig):
+    DEBUG = False
+
+
+class TestConfig(BaseConfig):
+    TESTING = True
+    DEBUG = True  # lets asset() tolerate a missing Vite manifest during tests
+    SQLALCHEMY_DATABASE_URI = "sqlite:///:memory:"
+    SQLALCHEMY_ENGINE_OPTIONS = {}  # always in-memory SQLite regardless of DATABASE_URL
+    WTF_CSRF_ENABLED = False
+
+
+_CONFIGS = {"development": DevConfig, "production": ProdConfig, "testing": TestConfig}
+
+
+def get_config(config_name: str | None = None):
+    """Resolve a config class from FLASK_ENV or an explicit name.
+
+    Defaults to `production` if unset, so an unconfigured deployment never
+    silently runs with DEBUG on.
+    """
+    name = config_name or os.environ.get("FLASK_ENV", "production")
+    try:
+        return _CONFIGS[name]
+    except KeyError as exc:
+        raise ValueError(f"Unknown config_name {name!r}; expected one of {list(_CONFIGS)}") from exc