"""Google OAuth provider for FastMCP.
This module provides a complete Google OAuth integration that's ready to use
with just a client ID and client secret. It handles all the complexity of
Google's OAuth flow, token validation, and user management.
Example:
```python
from fastmcp import FastMCP
from fastmcp.server.auth.providers.google import GoogleProvider
# Simple Google OAuth protection
auth = GoogleProvider(
client_id="your-google-client-id.apps.googleusercontent.com",
client_secret="your-google-client-secret"
)
mcp = FastMCP("My Protected Server", auth=auth)
```
"""
from __future__ import annotations
import time
import httpx
from pydantic import AnyHttpUrl, SecretStr, field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict
from fastmcp.server.auth import TokenVerifier
from fastmcp.server.auth.auth import AccessToken
from fastmcp.server.auth.oauth_proxy import OAuthProxy
from fastmcp.utilities.auth import parse_scopes
from fastmcp.utilities.logging import get_logger
from fastmcp.utilities.storage import KVStorage
from fastmcp.utilities.types import NotSet, NotSetT
logger = get_logger(__name__)
class GoogleProviderSettings(BaseSettings):
"""Settings for Google OAuth provider."""
model_config = SettingsConfigDict(
env_prefix="FASTMCP_SERVER_AUTH_GOOGLE_",
env_file=".env",
extra="ignore",
)
client_id: str | None = None
client_secret: SecretStr | None = None
base_url: AnyHttpUrl | str | None = None
redirect_path: str | None = None
required_scopes: list[str] | None = None
timeout_seconds: int | None = None
allowed_client_redirect_uris: list[str] | None = None
@field_validator("required_scopes", mode="before")
@classmethod
def _parse_scopes(cls, v):
return parse_scopes(v)
class GoogleTokenVerifier(TokenVerifier):
"""Token verifier for Google OAuth tokens.
Google OAuth tokens are opaque (not JWTs), so we verify them
by calling Google's tokeninfo API to check if they're valid and get user info.
"""
def __init__(
self,
*,
required_scopes: list[str] | None = None,
timeout_seconds: int = 10,
):
"""Initialize the Google token verifier.
Args:
required_scopes: Required OAuth scopes (e.g., ['openid', 'email'])
timeout_seconds: HTTP request timeout
"""
super().__init__(required_scopes=required_scopes)
self.timeout_seconds = timeout_seconds
async def verify_token(self, token: str) -> AccessToken | None:
"""Verify Google OAuth token by calling Google's tokeninfo API."""
try:
async with httpx.AsyncClient(timeout=self.timeout_seconds) as client:
# Use Google's tokeninfo endpoint to validate the token
response = await client.get(
"https://www.googleapis.com/oauth2/v1/tokeninfo",
params={"access_token": token},
headers={"User-Agent": "FastMCP-Google-OAuth"},
)
if response.status_code != 200:
logger.debug(
"Google token verification failed: %d",
response.status_code,
)
return None
token_info = response.json()
# Check if token is expired
expires_in = token_info.get("expires_in")
if expires_in and int(expires_in) <= 0:
logger.debug("Google token has expired")
return None
# Extract scopes from token info
scope_string = token_info.get("scope", "")
token_scopes = [
scope.strip() for scope in scope_string.split(" ") if scope.strip()
]
# Check required scopes
if self.required_scopes:
token_scopes_set = set(token_scopes)
required_scopes_set = set(self.required_scopes)
if not required_scopes_set.issubset(token_scopes_set):
logger.debug(
"Google token missing required scopes. Has %d, needs %d",
len(token_scopes_set),
len(required_scopes_set),
)
return None
# Get additional user info if we have the right scopes
user_data = {}
if "openid" in token_scopes or "profile" in token_scopes:
try:
userinfo_response = await client.get(
"https://www.googleapis.com/oauth2/v2/userinfo",
headers={
"Authorization": f"Bearer {token}",
"User-Agent": "FastMCP-Google-OAuth",
},
)
if userinfo_response.status_code == 200:
user_data = userinfo_response.json()
except Exception as e:
logger.debug("Failed to fetch Google user info: %s", e)
# Calculate expiration time
expires_at = None
if expires_in:
expires_at = int(time.time() + int(expires_in))
# Create AccessToken with Google user info
access_token = AccessToken(
token=token,
client_id=token_info.get(
"audience", "unknown"
), # Use audience as client_id
scopes=token_scopes,
expires_at=expires_at,
claims={
"sub": user_data.get("id")
or token_info.get("user_id", "unknown"),
"email": user_data.get("email"),
"name": user_data.get("name"),
"picture": user_data.get("picture"),
"given_name": user_data.get("given_name"),
"family_name": user_data.get("family_name"),
"locale": user_data.get("locale"),
"google_user_data": user_data,
"google_token_info": token_info,
},
)
logger.debug("Google token verified successfully")
return access_token
except httpx.RequestError as e:
logger.debug("Failed to verify Google token: %s", e)
return None
except Exception as e:
logger.debug("Google token verification error: %s", e)
return None
class GoogleProvider(OAuthProxy):
"""Complete Google OAuth provider for FastMCP.
This provider makes it trivial to add Google OAuth protection to any
FastMCP server. Just provide your Google OAuth app credentials and
a base URL, and you're ready to go.
Features:
- Transparent OAuth proxy to Google
- Automatic token validation via Google's tokeninfo API
- User information extraction from Google APIs
- Minimal configuration required
Example:
```python
from fastmcp import FastMCP
from fastmcp.server.auth.providers.google import GoogleProvider
auth = GoogleProvider(
client_id="123456789.apps.googleusercontent.com",
client_secret="GOCSPX-abc123...",
base_url="https://my-server.com"
)
mcp = FastMCP("My App", auth=auth)
```
"""
def __init__(
self,
*,
client_id: str | NotSetT = NotSet,
client_secret: str | NotSetT = NotSet,
base_url: AnyHttpUrl | str | NotSetT = NotSet,
redirect_path: str | NotSetT = NotSet,
required_scopes: list[str] | NotSetT = NotSet,
timeout_seconds: int | NotSetT = NotSet,
allowed_client_redirect_uris: list[str] | NotSetT = NotSet,
client_storage: KVStorage | None = None,
):
"""Initialize Google OAuth provider.
Args:
client_id: Google OAuth client ID (e.g., "123456789.apps.googleusercontent.com")
client_secret: Google OAuth client secret (e.g., "GOCSPX-abc123...")
base_url: Public URL of your FastMCP server (for OAuth callbacks)
redirect_path: Redirect path configured in Google OAuth app (defaults to "/auth/callback")
required_scopes: Required Google scopes (defaults to ["openid"]). Common scopes include:
- "openid" for OpenID Connect (default)
- "https://www.googleapis.com/auth/userinfo.email" for email access
- "https://www.googleapis.com/auth/userinfo.profile" for profile info
timeout_seconds: HTTP request timeout for Google API calls
allowed_client_redirect_uris: List of allowed redirect URI patterns for MCP clients.
If None (default), all URIs are allowed. If empty list, no URIs are allowed.
client_storage: Storage implementation for OAuth client registrations.
Defaults to file-based storage if not specified.
"""
settings = GoogleProviderSettings.model_validate(
{
k: v
for k, v in {
"client_id": client_id,
"client_secret": client_secret,
"base_url": base_url,
"redirect_path": redirect_path,
"required_scopes": required_scopes,
"timeout_seconds": timeout_seconds,
"allowed_client_redirect_uris": allowed_client_redirect_uris,
}.items()
if v is not NotSet
}
)
# Validate required settings
if not settings.client_id:
raise ValueError(
"client_id is required - set via parameter or FASTMCP_SERVER_AUTH_GOOGLE_CLIENT_ID"
)
if not settings.client_secret:
raise ValueError(
"client_secret is required - set via parameter or FASTMCP_SERVER_AUTH_GOOGLE_CLIENT_SECRET"
)
# Apply defaults
timeout_seconds_final = settings.timeout_seconds or 10
# Google requires at least one scope - openid is the minimal OIDC scope
required_scopes_final = settings.required_scopes or ["openid"]
allowed_client_redirect_uris_final = settings.allowed_client_redirect_uris
# Create Google token verifier
token_verifier = GoogleTokenVerifier(
required_scopes=required_scopes_final,
timeout_seconds=timeout_seconds_final,
)
# Extract secret string from SecretStr
client_secret_str = (
settings.client_secret.get_secret_value() if settings.client_secret else ""
)
# Initialize OAuth proxy with Google endpoints
super().__init__(
upstream_authorization_endpoint="https://accounts.google.com/o/oauth2/v2/auth",
upstream_token_endpoint="https://oauth2.googleapis.com/token",
upstream_client_id=settings.client_id,
upstream_client_secret=client_secret_str,
token_verifier=token_verifier,
base_url=settings.base_url,
redirect_path=settings.redirect_path,
issuer_url=settings.base_url, # We act as the issuer for client registration
allowed_client_redirect_uris=allowed_client_redirect_uris_final,
client_storage=client_storage,
)
logger.info(
"Initialized Google OAuth provider for client %s with scopes: %s",
settings.client_id,
required_scopes_final,
)