Settings & env vars

Everything the library reads from your environment or Django settings.

Settings layout — `MCP` bag

Every 0-mcp setting lives inside a single MCP = {...} dict in settings.py (DRF/Celery-style namespace):

# settings.py
MCP = {
    'CACHE_TTL': 300,
    'CACHE_TTL_ENABLE': True,
    'ENFORCE_TOKEN': True,
    'COOKIE_ID': 'sid',
    'RATE_LIMITS': {...},
}

Inside the bag the MCP_ prefix is redundant — 'MCP_API_KEY_RESOLVER' and 'API_KEY_RESOLVER' resolve to the same setting.

Environment variables

Variable	Required	Description
`REDIS_SERVER`	Yes	Redis hostname / address. Requires Redis 6.2 or newer (the framework uses `GETEX` for sliding session TTLs).
`REDIS_DB`	Yes	Redis database number
`REDIS_PREFIX`	No	Optional prefix applied to all Redis keys (use to isolate environments on a shared instance)

Django settings

Setting	Default	Description
`DEFAULT_AUTHENTICATED`	`True`	Class-level default for `BaseResource.authenticated`. Generated projects (`0-mcp init`) ship with this set to `False` so the demo boots without a configured api-key resolver — flip back to `True` (or override per-resource) before deploying.
`COOKIE_ID`	`'sessionid'`	Cookie name carrying the session id. Used by `AuthMiddleware`, `BaseResource` and the OpenAPI security scheme — set once in the bag and every entry point reads the same value.
`ALLOWED_ORIGINS`	`[]`	If set, requests must have an `Origin` (with `Referer` fallback) whose host ends with one of these origins
`TRUSTED_PROXIES`	`[]`	CIDRs allowed to set `X-Real-IP` / `X-Forwarded-For`
`ENFORCE_TOKEN`	`False`	Require `X-Token` anti-replay header on authenticated requests
`TOKEN_MAX_DRIFT_MS`	`30000`	Maximum clock drift (milliseconds) accepted when validating `X-Token`. Tighter values reduce the replay window; looser values tolerate slow clocks and event-loop pauses on the client.
`CREDENTIAL_PATHS`	`['/forgot', '/change_password', '/signup', '/reset', '/recover', '/register']`	Path-segment list that triggers the credential-path auto-defense (a tight per-IP rate-limit bucket on top of the regular API limits). Segment-based match — `/forgot` covers `/login/forgot`, `/user/forgot/...`, but not `/forgotten`. Setting this in your project replaces the framework default (no merge); copy the list to extend. Set to `[]` to disable.
`CREDENTIAL_RATE_LIMIT`	`{'limit': 5, 'window': 30}`	Per-IP rate limit applied to `CREDENTIAL_PATHS`. `window` in seconds. Defaults to 5 hits / 30s — tight enough to break credential-stuffing, loose enough to absorb legitimate retries (resend-email button, NAT-shared offices).
`READ_ONLY`	`False`	Global read-only gate. When `True`, every non-`GET` request returns `405` across all resources (REST + MCP) — overrides per-resource `allowed_methods`. Useful for safe-by-default deployments and projects generated by `0-mcp init` (the default unless you pass `--writable`).
`RATE_LIMITS`	sensible defaults	See Rate limiting page
`AUTO_SCOPE_CACHE_BY_ACCOUNT`	`True`	Auto-fold `self.account_id` into the cache key so multi-tenant deployments don't leak cache across tenants. Set to `False` only on single-tenant deployments that want the legacy key shape. See Cache.
`CACHE_TTL`	`None`	Project-level default for `BaseResource.cache_ttl` (seconds). When unset, the framework default of 120s applies. Resources that declare `cache_ttl = N` keep their explicit value. See Cache.
`CACHE_TTL_ENABLE`	`True`	Master kill switch. When `False`, every `cache=True` resource is treated as `cache=False` at runtime — no read, no write to Redis. Useful for incident response without code edits.
`SESSION_TTL`	`1800`	Sliding TTL (seconds) for cookie-based sessions. Renewed on every authenticated request via Redis `GETEX` (Redis 6.2+ required).
`API_SESSION_TTL`	`300`	Sliding TTL (seconds) for the API-key → session mapping. Renewed on every authenticated request via Redis `GETEX`.
`MCP_LIST_OMIT_NULL`	`False`	Strip `null` fields from MCP `list_*` tool responses to shrink payloads. Useful for agent surfaces where empty fields just consume tokens.
`MCP_EDIT_OMIT_NULL`	`False`	Same as `MCP_LIST_OMIT_NULL` but for `get_` / `update_` tool responses.
`MAX_4XX_PER_MINUTE`	`10`	Anti-scanner: when an IP returns more than this many 4xx responses in 60s, it is parked in the block list for `BLOCK_DURATION_SECONDS`.
`MAX_4XX_PER_HOUR`	`30`	Same as `MAX_4XX_PER_MINUTE` but on a 1-hour window. Hitting either threshold triggers the block.
`BLOCK_DURATION_SECONDS`	`86400`	How long an IP stays in the block list once tripped. Defaults to 24h.
`BLOCK_PATTERNS`	`None` (framework baseline)	Regex list applied to request paths — known vulnerability scanners are blocked pre-emptively. Pass a list to replace the baseline, `[]` to disable.
`BLOCK_USER_AGENTS`	`None` (framework baseline)	Same as `BLOCK_PATTERNS` but for the `User-Agent` header.
`API_KEY_RESOLVER`	`None`	Dotted path (or callable) to a custom API key resolver. Receives the raw key, returns a session dict or `None`. When unset, the default four-segment-hash resolver is used. (`MCP_API_KEY_RESOLVER` is also accepted — the prefix is redundant inside the bag.)
`DEBUG`	`False`	When `False`, unhandled exceptions become sanitized 500s

Middleware order

In MIDDLEWARE:

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    # ... your other middleware ...
    'zeromcp.SecurityMiddleware',     # blocks scanners early
    'zeromcp.AuthMiddleware',         # handled by dispatch, but kept for non-resource views
    'zeromcp.ExceptionMiddleware',    # catches HTTPException
]

Database router (multi-tenant)

DATABASE_ROUTERS = ['zeromcp.DBRouter']

Required only if you use multi-tenant.