Spoolman/spoolman/main.py

"""Main entrypoint to the server."""

import json
import logging
import subprocess
from logging.handlers import TimedRotatingFileHandler
from pathlib import Path

import uvicorn
from fastapi import FastAPI
from fastapi.middleware.cors import CORSMiddleware
from fastapi.middleware.gzip import GZipMiddleware
from fastapi.responses import PlainTextResponse, RedirectResponse, Response
from prometheus_client import generate_latest
from scheduler.asyncio.scheduler import Scheduler

from spoolman import env, externaldb, security
from spoolman.api.v1.router import app as v1_app
from spoolman.client import SinglePageApplication
from spoolman.database import database
from spoolman.prometheus.metrics import registry

# Define a console logger
console_handler = logging.StreamHandler()
console_handler.setFormatter(logging.Formatter("%(name)-26s %(levelname)-8s %(message)s"))

# Setup the spoolman logger, which all spoolman modules will use
log_level = env.get_logging_level()
root_logger = logging.getLogger()
root_logger.setLevel(log_level)
root_logger.addHandler(console_handler)

# Fix uvicorn logging
logging.getLogger("uvicorn").setLevel(log_level)
if logging.getLogger("uvicorn").handlers:
    logging.getLogger("uvicorn").removeHandler(logging.getLogger("uvicorn").handlers[0])
logging.getLogger("uvicorn").addHandler(console_handler)

logging.getLogger("uvicorn.error").setLevel(log_level)

access_handlers = logging.getLogger("uvicorn.access").handlers
if access_handlers:
    logging.getLogger("uvicorn.access").setLevel(log_level)
    logging.getLogger("uvicorn.access").removeHandler(access_handlers[0])
    logging.getLogger("uvicorn.access").addHandler(console_handler)

# Get logger instance for this module
logger = logging.getLogger(__name__)


# Setup FastAPI
app = FastAPI(
    debug=env.is_debug_mode(),
    title="Spoolman",
    version=env.get_version(),
)
app.add_middleware(GZipMiddleware)
app.mount(env.get_base_path() + "/api/v1", v1_app)


# WA for prometheus /metrics bind with SinglePageApp at root
@app.get(
    env.get_base_path() + "/metrics",
    response_class=PlainTextResponse,
    name="Get metrics for prometheus",
    description=(
        "Get app metrics for prometheusIf enabled SPOOLMAN_METRICS_ENABLED returned metrics by Spools and Filaments"
    ),
)
def get_metrics() -> bytes:
    """Return prometheus metrics."""
    return generate_latest(registry)


base_path = env.get_base_path()
if base_path != "":
    logger.info("Base path is: %s", base_path)

    # If base path is set, add a redirect from non-slash suffix to slash
    # suffix. Otherwise it won't work.
    @app.get(base_path)
    def root_redirect() -> Response:
        """Redirect to base path."""
        return RedirectResponse(base_path + "/")


# Return a dynamic js config file
# This is so that the client side can access the base path variable.
@app.get(env.get_base_path() + "/config.js")
def get_configjs() -> Response:
    """Return a dynamic js config file."""
    # JSON-encode rather than hand-quoting. Checking for `"` alone missed the backslash, which a
    # base path ending in one would use to escape the closing quote and break out of the literal.
    # JSON is a subset of JS here, so json.dumps produces a correct JS string literal.
    return Response(
        content=f"""
window.SPOOLMAN_BASE_PATH = {json.dumps(base_path)};
""",
        media_type="text/javascript",
    )


# Mount the client side app. The new Svelte client is served by default; set
# SPOOLMAN_LEGACY_CLIENT to fall back to the old React client.
if env.is_legacy_client_enabled():
    logger.info("Serving the legacy (React) client.")
    app.mount(
        base_path,
        app=SinglePageApplication(
            directory="client/dist",
            base_path=env.get_base_path(),
            fallback_document="index.html",
            rewrite_asset_paths=True,
        ),
    )
else:
    app.mount(
        base_path,
        app=SinglePageApplication(
            directory="client_v2/build",
            base_path=env.get_base_path(),
            fallback_document="200.html",
            rewrite_asset_paths=False,
        ),
    )


def add_trusted_origin_middleware() -> None:
    """Refuse writes and websocket handshakes from browser origins we do not trust."""
    if security.trusts_all_origins():
        # Already warned about by trusts_all_origins(); adding the middleware would be a no-op.
        return
    trusted = security.get_trusted_origins()
    if trusted:
        logger.info("Trusting writes and websockets from this instance's own origin, plus: %s", sorted(trusted))
    else:
        logger.info("Trusting writes and websockets from this instance's own origin only.")
    app.add_middleware(security.TrustedOriginMiddleware)


def add_trusted_host_middleware() -> None:
    """Refuse requests addressed to a hostname this instance has no reason to answer to.

    Opt-in, so a deployment that configures nothing is unaffected; see
    security.is_host_checking_enabled for why this guard alone is not on by default.
    """
    if not security.is_host_checking_enabled():
        return
    logger.info("Answering to these hostnames: %s.", security.describe_allowed_hosts())
    app.add_middleware(security.TrustedHostMiddleware)


def add_cors_middleware() -> None:
    """Add CORS middleware to the FastAPI app based on environment settings."""
    origins = []
    if env.is_debug_mode():
        logger.warning("Running in debug mode, allowing all origins.")
        origins = ["*"]
    elif env.is_cors_defined():
        cors_origins = env.get_cors_origin()
        if cors_origins:
            # Log the raw value alongside the parsed one so a typo in the operator's list is visible.
            logger.info("CORS origins defined: %s (parsed from %r)", cors_origins, env.get_cors_origin_raw())
            origins = cors_origins
        else:
            logger.warning(
                "SPOOLMAN_CORS_ORIGIN is set to %r but contains no origins, no CORS will be applied.",
                env.get_cors_origin_raw(),
            )

    if not origins:
        return

    # Starlette resolves allow_origins=["*"] with allow_credentials=True by echoing the caller's
    # origin back and setting Access-Control-Allow-Credentials, which tells the browser it may
    # send cookies to any site that asks. Spoolman has no cookies of its own, but plenty of
    # instances sit behind a reverse proxy that does the authentication with one -- and there,
    # this combination lets any website the user visits make authenticated requests as them.
    allow_credentials = security.WILDCARD_ORIGIN not in origins
    if not allow_credentials:
        logger.warning("Allowing all CORS origins, so credentialed cross-origin requests are refused.")

    app.add_middleware(
        CORSMiddleware,
        allow_origins=origins,
        allow_credentials=allow_credentials,
        allow_methods=["*"],
        allow_headers=["*"],
        expose_headers=["X-Total-Count"],
    )


# Order matters: middleware added last is outermost. CORS wraps both guards, so that a legitimate
# cross-origin client can read the 403 body instead of an opaque CORS error, and the host guard
# wraps the origin guard, because a rebound host makes the origin check agree with the attacker.
add_trusted_origin_middleware()
add_trusted_host_middleware()
add_cors_middleware()


def add_file_logging() -> None:
    """Add file logging to the root logger."""
    # Define a file logger with log rotation
    log_file = env.get_logs_dir().joinpath("spoolman.log")
    file_handler = TimedRotatingFileHandler(log_file, when="midnight", backupCount=5)
    file_handler.setFormatter(logging.Formatter("%(asctime)s:%(levelname)s:%(message)s", "%Y-%m-%d %H:%M:%S"))
    root_logger.addHandler(file_handler)

    logging.getLogger("uvicorn").addHandler(file_handler)
    access_handlers = logging.getLogger("uvicorn.access").handlers
    if access_handlers:
        logging.getLogger("uvicorn.access").addHandler(file_handler)


@app.on_event("startup")
async def startup() -> None:
    """Run the service's startup sequence."""
    # Check that the data directory is writable
    env.check_write_permissions()

    # Don't add file logging until we have verified that the data directory is writable
    add_file_logging()

    logger.info(
        "Starting Spoolman v%s (commit: %s) (built: %s)",
        app.version,
        env.get_commit_hash(),
        env.get_build_date(),
    )

    logger.info("Using data directory: %s", env.get_data_dir().resolve())
    logger.info("Using logs directory: %s", env.get_logs_dir().resolve())
    logger.info("Using backups directory: %s", env.get_backups_dir().resolve())

    logger.info("Setting up database...")
    database.setup_db(database.get_connection_url())

    logger.info("Performing migrations...")
    # Run alembic in a subprocess.
    # There is some issue with the uvicorn worker that causes the process to hang when running alembic directly.
    # See: https://github.com/sqlalchemy/alembic/discussions/1155
    project_root = Path(__file__).parent.parent
    subprocess.run(["alembic", "upgrade", "head"], check=True, cwd=project_root)  # noqa: ASYNC221, S607

    # Setup scheduler
    schedule = Scheduler()
    database.schedule_tasks(schedule)
    externaldb.schedule_tasks(schedule)

    logger.info("Startup complete.")

    if env.is_docker() and not env.is_data_dir_mounted():
        logger.warning("!!!! WARNING !!!!")
        logger.warning("!!!! WARNING !!!!")
        logger.warning("The data directory is not mounted.")
        logger.warning(
            'Spoolman stores its database in the container directory "%s". '
            "If this directory isn't mounted to the host OS, the database will be lost when the container is stopped.",
            env.get_data_dir(),
        )
        logger.warning(
            "Please carefully read the docker part of the README.md file, "
            "and ensure your docker-compose file matches the example.",
        )
        logger.warning("!!!! WARNING !!!!")
        logger.warning("!!!! WARNING !!!!")


if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)