serve.py

"""
Subclasses the bokeh serve commandline handler to extend it in various
ways.
"""

import ast
import base64
import logging
import os
import pathlib

from glob import glob
from types import ModuleType

from bokeh.application import Application
from bokeh.application.handlers.document_lifecycle import (
    DocumentLifecycleHandler,
)
from bokeh.application.handlers.function import FunctionHandler
from bokeh.command.subcommands.serve import Serve as _BkServe
from bokeh.command.util import build_single_handler_applications
from bokeh.core.validation import silence
from bokeh.core.validation.warnings import EMPTY_LAYOUT
from bokeh.server.contexts import ApplicationContext
from tornado.ioloop import PeriodicCallback
from tornado.web import StaticFileHandler

from ..auth import BasicAuthProvider, OAuthProvider
from ..config import config
from ..io.document import _cleanup_doc
from ..io.liveness import LivenessHandler
from ..io.reload import record_modules, watch
from ..io.rest import REST_PROVIDERS
from ..io.server import INDEX_HTML, get_static_routes, set_curdoc
from ..io.state import state
from ..util import fullpath

log = logging.getLogger(__name__)

def parse_var(s):
    """
    Parse a key, value pair, separated by '='
    That's the reverse of ShellArgs.

    On the command line (argparse) a declaration will typically look like:
        foo=hello
    or
        foo="hello world"
    """
    items = s.split('=')
    key = items[0].strip() # we remove blanks around keys, as is logical
    if len(items) > 1:
        # rejoin the rest:
        value = '='.join(items[1:])
    return (key, value)


def parse_vars(items):
    """
    Parse a series of key-value pairs and return a dictionary
    """
    return dict((parse_var(item) for item in items))


class AdminApplicationContext(ApplicationContext):

    def __init__(self, application, unused_timeout=15000, **kwargs):
        super().__init__(application, **kwargs)
        self._unused_timeout = unused_timeout
        self._cleanup_cb = None

    async def cleanup_sessions(self):
        await self._cleanup_sessions(self._unused_timeout)

    def run_load_hook(self):
        self._cleanup_cb = PeriodicCallback(self.cleanup_sessions, self._unused_timeout)
        self._cleanup_cb.start()
        super().run_load_hook()

    def run_unload_hook(self):
        if self._cleanup_cb:
            self._cleanup_cb.stop()
        super().run_unload_hook()


class Serve(_BkServe):

    args = _BkServe.args + (
        ('--static-dirs', dict(
            metavar="KEY=VALUE",
            nargs='+',
            help=("Static directories to serve specified as key=value "
                  "pairs mapping from URL route to static file directory.")
        )),
        ('--basic-auth', dict(
            action = 'store',
            type   = str,
            help   = "Password or filepath to use with Basic Authentication."
        )),
        ('--oauth-provider', dict(
            action = 'store',
            type   = str,
            help   = "The OAuth2 provider to use."
        )),
        ('--oauth-key', dict(
            action  = 'store',
            type    = str,
            help    = "The OAuth2 key to use",
        )),
        ('--oauth-secret', dict(
            action  = 'store',
            type    = str,
            help    = "The OAuth2 secret to use",
        )),
        ('--oauth-redirect-uri', dict(
            action  = 'store',
            type    = str,
            help    = "The OAuth2 redirect URI",
        )),
        ('--oauth-extra-params', dict(
            action  = 'store',
            type    = str,
            help    = "Additional parameters to use.",
        )),
        ('--oauth-jwt-user', dict(
            action  = 'store',
            type    = str,
            help    = "The key in the ID JWT token to consider the user.",
        )),
        ('--oauth-encryption-key', dict(
            action = 'store',
            type    = str,
            help    = "A random string used to encode the user information."
        )),
        ('--oauth-error-template', dict(
            action = 'store',
            type    = str,
            help    = "A random string used to encode the user information."
        )),
        ('--oauth-expiry-days', dict(
            action  = 'store',
            type    = float,
            help    = "Expiry off the OAuth cookie in number of days.",
            default = 1
        )),
        ('--oauth-refresh-tokens', dict(
            action  = 'store_true',
            help    = "Whether to automatically OAuth access tokens when they expire.",
        )),
        ('--oauth-guest-endpoints', dict(
            action  = 'store',
            nargs   = '*',
            help    = "List of endpoints that can be accessed as a guest without authenticating.",
        )),
        ('--oauth-optional', dict(
            action  = 'store_true',
            help    = (
                "Whether the user will be forced to go through login flow "
                "or if they can access all applications as a guest."
            )
        )),
        ('--login-endpoint', dict(
            action  = 'store',
            type    = str,
            help    = "Endpoint to serve the authentication login page on."
        )),
        ('--logout-endpoint', dict(
            action  = 'store',
            type    = str,
            help    = "Endpoint to serve the authentication logout page on."
        )),
        ('--auth-template', dict(
            action  = 'store',
            type    = str,
            help    = "Template to serve when user is unauthenticated."
        )),
        ('--logout-template', dict(
            action  = 'store',
            type    = str,
            help    = "Template to serve logout page."
        )),
        ('--basic-login-template', dict(
            action  = 'store',
            type    = str,
            help    = "Template to serve for Basic Authentication login page."
        )),
        ('--rest-provider', dict(
            action = 'store',
            type   = str,
            help   = "The interface to use to serve REST API"
        )),
        ('--rest-endpoint', dict(
            action  = 'store',
            type    = str,
            help    = "Endpoint to store REST API on.",
            default = 'rest'
        )),
        ('--rest-session-info', dict(
            action  = 'store_true',
            help    = "Whether to serve session info on the REST API"
        )),
        ('--session-history', dict(
            action  = 'store',
            type    = int,
            help    = "The length of the session history to record.",
            default = 0
        )),
        ('--warm', dict(
            action  = 'store_true',
            help    = "Whether to execute scripts on startup to warm up the server."
        )),
        ('--admin', dict(
            action  = 'store_true',
            help    = "Whether to add an admin panel."
        )),
        ('--admin-endpoint', dict(
            action = 'store',
            type    = str,
            help    = "Name to use for the admin endpoint.",
            default = None
        )),
        ('--admin-log-level', dict(
            action  = 'store',
            default = None,
            choices = ('debug', 'info', 'warning', 'error', 'critical'),
            help    = "One of: debug (default), info, warning, error or critical",
        )),
        ('--profiler', dict(
            action  = 'store',
            type    = str,
            help    = "The profiler to use by default, e.g. pyinstrument, snakeviz or memray."
        )),
        ('--autoreload', dict(
            action  = 'store_true',
            help    = "Whether to autoreload source when script changes."
        )),
        ('--num-threads', dict(
            action  = 'store',
            type    = int,
            help    = "Whether to start a thread pool which events are dispatched to.",
            default = None
        )),
        ('--setup', dict(
            action  = 'store',
            type    = str,
            help    = "Path to a setup script to run before server starts.",
            default = None
        )),
        ('--liveness', dict(
            action  = 'store_true',
            help    = "Whether to add a liveness endpoint."
        )),
        ('--liveness-endpoint', dict(
            action  = 'store',
            type    = str,
            help    = "The endpoint for the liveness API.",
            default = "liveness"
        )),
        ('--reuse-sessions', dict(
            action  = 'store_true',
            help    = "Whether to reuse sessions when serving the initial request.",
        )),
        ('--global-loading-spinner', dict(
            action  = 'store_true',
            help    = "Whether to add a global loading spinner to the application(s).",
        )),
    )

    # Supported file extensions
    _extensions = ['.py', '.ipynb', '.md']

    def customize_applications(self, args, applications):
        if args.index and not args.index.endswith('.html'):
            index = args.index.split(os.path.sep)[-1]
            for ext in self._extensions:
                if index.endswith(ext):
                    index = index[:-len(ext)]
            if f'/{index}' in applications:
                applications['/'] = applications[f'/{index}']
        return super().customize_applications(args, applications)

    def warm_applications(self, applications, reuse_sessions):
        from ..io.session import generate_session
        for path, app in applications.items():
            session = generate_session(app)
            with set_curdoc(session.document):
                if config.session_key_func:
                    reuse_sessions = False
                else:
                    state._session_key_funcs[path] = lambda r: r.path
                    state._sessions[path] = session
                    session.block_expiration()
                state._on_load(None)
            _cleanup_doc(session.document, destroy=not reuse_sessions)

    def customize_kwargs(self, args, server_kwargs):
        '''Allows subclasses to customize ``server_kwargs``.

        Should modify and return a copy of the ``server_kwargs`` dictionary.
        '''
        kwargs = dict(server_kwargs)
        if 'index' not in kwargs:
            kwargs['index'] = INDEX_HTML
        elif kwargs['index'].endswith('.html'):
            kwargs['index'] = os.path.abspath(kwargs['index'])

        # Handle tranquilized functions in the supplied functions
        kwargs['extra_patterns'] = patterns = kwargs.get('extra_patterns', [])

        static_dirs = parse_vars(args.static_dirs) if args.static_dirs else {}
        patterns += get_static_routes(static_dirs)

        files = []
        for f in args.files:
            if args.glob:
                files.extend(glob(f))
            else:
                files.append(f)

        if args.index and not args.index.endswith('.html'):
            found = False
            for ext in self._extensions:
                index = args.index if args.index.endswith(ext) else f'{args.index}{ext}'
                if any(f.endswith(index) for f in files):
                    found = True
            # Check for directory style applications
            for f in files:
                if '.' in os.path.basename(f): # Skip files with extension
                    continue
                if args.index == os.path.basename(f) or args.index == f:
                    found = True
            if not found:
                raise ValueError(
                    "The --index argument must either specify a jinja2 "
                    "template with a .html file extension or select one "
                    "of the applications being served as the default. "
                    f"The specified application {index!r} could not be "
                    "found."
                )

        # Handle tranquilized functions in the supplied functions
        if args.rest_provider in REST_PROVIDERS:
            pattern = REST_PROVIDERS[args.rest_provider](files, args.rest_endpoint)
            patterns.extend(pattern)
        elif args.rest_provider is not None:
            raise ValueError("rest-provider %r not recognized." % args.rest_provider)

        config.autoreload = args.autoreload
        config.global_loading_spinner = args.global_loading_spinner
        config.reuse_sessions = args.reuse_sessions

        if config.autoreload:
            for f in files:
                watch(f)

        if args.setup:
            setup_path = args.setup
            with open(setup_path) as f:
                setup_source = f.read()
            nodes = ast.parse(setup_source, os.fspath(setup_path))
            code = compile(nodes, filename=setup_path, mode='exec', dont_inherit=True)
            module_name = 'panel_setup_module'
            module = ModuleType(module_name)
            module.__dict__['__file__'] = fullpath(setup_path)
            exec(code, module.__dict__)
            state._setup_module = module

        if args.warm or args.autoreload:
            argvs = {f: args.args for f in files}
            applications = build_single_handler_applications(files, argvs)
            if args.autoreload:
                with record_modules(list(applications.values())):
                    self.warm_applications(
                        applications, args.reuse_sessions
                    )
            else:
                self.warm_applications(applications, args.reuse_sessions)

        if args.liveness:
            argvs = {f: args.args for f in files}
            applications = build_single_handler_applications(files, argvs)
            patterns += [(r"/%s" % args.liveness_endpoint, LivenessHandler, dict(applications=applications))]

        config.profiler = args.profiler
        if args.admin:
            from ..io.admin import admin_panel
            from ..io.server import per_app_patterns

            # If `--admin-endpoint` is not set, then we default to the `/admin` path.
            admin_path = "/admin"
            if args.admin_endpoint:
                admin_path = args.admin_endpoint
                admin_path = admin_path if admin_path.startswith('/') else f'/{admin_path}'

            config._admin = True
            app = Application(FunctionHandler(admin_panel))
            unused_timeout = args.check_unused_sessions or 15000
            state._admin_context = app_ctx = AdminApplicationContext(
                app, unused_timeout=unused_timeout, url=admin_path
            )
            if all(not isinstance(handler, DocumentLifecycleHandler) for handler in app._handlers):
                app.add(DocumentLifecycleHandler())
            app_patterns = []
            for p in per_app_patterns:
                route = admin_path + p[0]
                context = {"application_context": app_ctx}
                app_patterns.append((route, p[1], context))

            websocket_path = None
            for r in app_patterns:
                if r[0].endswith("/ws"):
                    websocket_path = r[0]
            if not websocket_path:
                raise RuntimeError("Couldn't find websocket path")
            for r in app_patterns:
                r[2]["bokeh_websocket_path"] = websocket_path
            try:
                import snakeviz
                SNAKEVIZ_PATH = os.path.join(os.path.dirname(snakeviz.__file__), 'static')
                app_patterns.append(
                    ('/snakeviz/static/(.*)', StaticFileHandler, dict(path=SNAKEVIZ_PATH))
                )
            except Exception:
                pass
            patterns.extend(app_patterns)
            if args.admin_log_level is not None:
                if os.environ.get('PANEL_ADMIN_LOG_LEVEL'):
                    raise ValueError(
                        "admin_log_level supplied both using the environment variable "
                        "PANEL_ADMIN_LOG_LEVEL and as an explicit argument, only the "
                        "value supplied to the environment variable is used "
                    )
                else:
                    config.admin_log_level = args.admin_log_level.upper()

        config.session_history = args.session_history
        if args.rest_session_info:
            pattern = REST_PROVIDERS['param'](files, 'rest')
            patterns.extend(pattern)
            state.publish('session_info', state, ['session_info'])

        if args.num_threads is not None:
            if config.nthreads is not None:
                raise ValueError(
                    "Supply num_threads either using the environment variable "
                    "PANEL_NUM_THREADS or as an explicit argument, not both."
                )
            config.nthreads = args.num_threads

        if args.auth_template:
            authpath = pathlib.Path(args.auth_template)
            if not authpath.is_file():
                raise ValueError(
                    f"The supplied auth-template {args.auth_template} does not "
                    "exist, ensure you supply and existing Jinja2 template."
                )
            config.auth_template = str(authpath.absolute())

        if args.logout_template:
            logout_template = str(pathlib.Path(args.logout_template).absolute())
        else:
            logout_template = None

        if args.basic_auth and config.basic_auth:
            raise ValueError(
                "Turn on Basic authentication using environment variable "
                "or via explicit argument, not both"
            )

        if args.basic_login_template:
            login_template = args.basic_login_template
            authpath = pathlib.Path(login_template)
            if not authpath.is_file():
                raise ValueError(
                    f"The supplied auth-template {login_template} does not "
                    "exist, ensure you supply and existing Jinja2 template."
                )
        else:
            login_template = None

        login_endpoint = args.login_endpoint or '/login'
        login_endpoint = login_endpoint if login_endpoint.startswith('/') else f'/{login_endpoint}'
        logout_endpoint = args.logout_endpoint or '/logout'
        logout_endpoint = logout_endpoint if logout_endpoint.startswith('/') else f'/{logout_endpoint}'

        if args.oauth_error_template:
            error_template = str(pathlib.Path(args.oauth_error_template).absolute())
        elif config.auth_template:
            error_template = config.auth_template
        else:
            error_template = None

        if args.oauth_guest_endpoints:
            config.oauth_guest_endpoints = args.oauth_guest_endpoints
        if args.oauth_optional:
            config.oauth_optional = args.oauth_optional

        if args.basic_auth:
            config.basic_auth = args.basic_auth
        if config.basic_auth:
            kwargs['auth_provider'] = BasicAuthProvider(
                login_endpoint=login_endpoint,
                logout_endpoint=logout_endpoint,
                login_template=login_template,
                logout_template=logout_template,
                guest_endpoints=config.oauth_guest_endpoints,
            )

        if args.cookie_secret and config.cookie_secret:
            raise ValueError(
                "Supply cookie secret either using environment "
                "variable or via explicit argument, not both."
            )
        elif args.cookie_secret:
            config.cookie_secret = args.cookie_secret

        # Check only one auth is used.
        if args.oauth_provider and config.oauth_provider:
                raise ValueError(
                    "Supply OAuth provider either using environment variable "
                    "or via explicit argument, not both."
                )
        if args.oauth_provider:
            config.oauth_provider = args.oauth_provider
        if config.oauth_provider:
            config.oauth_refresh_tokens = args.oauth_refresh_tokens
            config.oauth_expiry = args.oauth_expiry_days
            if config.oauth_key and args.oauth_key:
                raise ValueError(
                    "Supply OAuth key either using environment variable "
                    "or via explicit argument, not both."
                )
            elif args.oauth_key:
                config.oauth_key = args.oauth_key
            elif not config.oauth_key:
                raise ValueError(
                    "When enabling an OAuth provider you must supply "
                    "a valid oauth_key either using the --oauth-key "
                    "CLI argument or PANEL_OAUTH_KEY environment "
                    "variable."
                )

            if not config.cookie_secret:
                raise ValueError(
                    "When enabling an OAuth provider you must supply "
                    "a valid cookie_secret either using the --cookie-secret "
                    "CLI argument or the PANEL_COOKIE_SECRET environment "
                    "variable."
                )

            if config.oauth_secret and args.oauth_secret:
                raise ValueError(
                    "Supply OAuth secret either using environment variable "
                    "or via explicit argument, not both."
                )
            elif args.oauth_secret:
                config.oauth_secret = args.oauth_secret
            elif not config.oauth_secret:
                raise ValueError(
                    "When enabling an OAuth provider you must supply "
                    "a valid OAuth secret either using the --oauth-secret "
                    "CLI argument or PANEL_OAUTH_SECRET environment "
                    "variable."
                )

            if args.oauth_extra_params:
                config.oauth_extra_params = ast.literal_eval(args.oauth_extra_params)

            if config.oauth_encryption_key and args.oauth_encryption_key:
                raise ValueError(
                    "Supply OAuth encryption key either using environment "
                    "variable or via explicit argument, not both."
                )
            elif args.oauth_encryption_key:
                encryption_key = args.oauth_encryption_key.encode('ascii')
                try:
                    key = base64.urlsafe_b64decode(encryption_key)
                except Exception:
                    raise ValueError("OAuth encryption key was not a valid base64 "
                                     "string. Generate an encryption key with "
                                     "`panel oauth-secret` and ensure you did not "
                                     "truncate the returned string.") from None
                if len(key) != 32:
                    raise ValueError(
                        "OAuth encryption key must be 32 url-safe "
                        "base64-encoded bytes."
                    )
                config.oauth_encryption_key = encryption_key
            elif not config.oauth_encryption_key:
                print("WARNING: OAuth has not been configured with an " # noqa: T201
                      "encryption key and will potentially leak "
                      "credentials in cookies and a JWT token embedded "
                      "in the served website. Use at your own risk or "
                      "generate a key with the `panel oauth-secret` CLI "
                      "command and then provide it to `panel serve` "
                      "using the PANEL_OAUTH_ENCRYPTION environment "
                      "variable or the --oauth-encryption-key CLI "
                      "argument.")

            if config.oauth_encryption_key:
                try:
                    from cryptography.fernet import Fernet
                except ImportError:
                    raise ImportError(
                        "Using OAuth2 provider with Panel requires the "
                        "cryptography library. Install it with `pip install "
                        "cryptography` or `conda install cryptography`."
                    ) from None
                state.encryption = Fernet(config.oauth_encryption_key)

            kwargs['auth_provider'] = OAuthProvider(
                login_endpoint=login_endpoint,
                logout_endpoint=logout_endpoint,
                login_template=login_template,
                logout_template=logout_template,
                error_template=error_template,
                guest_endpoints=config.oauth_guest_endpoints,
            )

            if args.oauth_redirect_uri and config.oauth_redirect_uri:
                raise ValueError(
                    "Supply OAuth redirect URI either using environment "
                    "variable or via explicit argument, not both."
                )
            elif args.oauth_redirect_uri:
                config.oauth_redirect_uri = args.oauth_redirect_uri

            if args.oauth_jwt_user and config.oauth_jwt_user:
                raise ValueError(
                    "Supply OAuth JWT user either using environment "
                    "variable or via explicit argument, not both."
                )
            elif args.oauth_jwt_user:
                config.oauth_jwt_user = args.oauth_jwt_user

        if config.cookie_secret:
            kwargs['cookie_secret'] = config.cookie_secret

        return kwargs

    def invoke(self, args):
        # Empty layout are valid and the Bokeh warning is silenced as usually
        # not relevant to Panel users.
        silence(EMPTY_LAYOUT, True)
        super().invoke(args)