lemur/lemur/factory.py

"""
.. module: lemur.factory
    :platform: Unix
    :synopsis: This module contains all the needed functions to allow
    the factory app creation.

    :copyright: (c) 2018 by Netflix Inc., see AUTHORS for more
    :license: Apache, see LICENSE for more details.
.. moduleauthor:: Kevin Glisson <kglisson@netflix.com>

"""
import os
import imp
import errno
import pkg_resources

from logging import Formatter, StreamHandler
from logging.handlers import RotatingFileHandler

from flask import Flask

from lemur.certificates.hooks import activate_debug_dump
from lemur.common.health import mod as health
from lemur.extensions import db, migrate, principal, smtp_mail, metrics, sentry, cors


DEFAULT_BLUEPRINTS = (
    health,
)

API_VERSION = 1


def create_app(app_name=None, blueprints=None, config=None):
    """
    Lemur application factory

    :param config:
    :param app_name:
    :param blueprints:
    :return:
    """
    if not blueprints:
        blueprints = DEFAULT_BLUEPRINTS
    else:
        blueprints = blueprints + DEFAULT_BLUEPRINTS

    if not app_name:
        app_name = __name__

    app = Flask(app_name)
    configure_app(app, config)
    configure_blueprints(app, blueprints)
    configure_extensions(app)
    configure_logging(app)
    install_plugins(app)

    @app.teardown_appcontext
    def teardown(exception=None):
        if db.session:
            db.session.remove()

    return app


def from_file(file_path, silent=False):
    """
    Updates the values in the config from a Python file.  This function
    behaves as if the file was imported as module with the

    :param file_path:
    :param silent:
    """
    d = imp.new_module('config')
    d.__file__ = file_path
    try:
        with open(file_path) as config_file:
            exec(compile(config_file.read(),  # nosec: config file safe
                 file_path, 'exec'), d.__dict__)
    except IOError as e:
        if silent and e.errno in (errno.ENOENT, errno.EISDIR):
            return False
        e.strerror = 'Unable to load configuration file (%s)' % e.strerror
        raise
    return d


def configure_app(app, config=None):
    """
    Different ways of configuration

    :param app:
    :param config:
    :return:
    """
    # respect the config first
    if config and config != 'None':
        app.config['CONFIG_PATH'] = config
        app.config.from_object(from_file(config))
    else:
        try:
            app.config.from_envvar("LEMUR_CONF")
        except RuntimeError:
            # look in default paths
            if os.path.isfile(os.path.expanduser("~/.lemur/lemur.conf.py")):
                app.config.from_object(from_file(os.path.expanduser("~/.lemur/lemur.conf.py")))
            else:
                app.config.from_object(from_file(os.path.join(os.path.dirname(os.path.realpath(__file__)), 'default.conf.py')))

    # we don't use this
    app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False


def configure_extensions(app):
    """
    Attaches and configures any needed flask extensions
    to our app.

    :param app:
    """
    db.init_app(app)
    migrate.init_app(app, db)
    principal.init_app(app)
    smtp_mail.init_app(app)
    metrics.init_app(app)
    sentry.init_app(app)

    if app.config['CORS']:
        app.config['CORS_HEADERS'] = 'Content-Type'
        cors.init_app(app, resources=r'/api/*', headers='Content-Type', origin='*', supports_credentials=True)


def configure_blueprints(app, blueprints):
    """
    We prefix our APIs with their given version so that we can support
    multiple concurrent API versions.

    :param app:
    :param blueprints:
    """
    for blueprint in blueprints:
        app.register_blueprint(blueprint, url_prefix="/api/{0}".format(API_VERSION))


def configure_logging(app):
    """
    Sets up application wide logging.

    :param app:
    """
    handler = RotatingFileHandler(app.config.get('LOG_FILE', 'lemur.log'), maxBytes=10000000, backupCount=100)

    handler.setFormatter(Formatter(
        '%(asctime)s %(levelname)s: %(message)s '
        '[in %(pathname)s:%(lineno)d]'
    ))

    handler.setLevel(app.config.get('LOG_LEVEL', 'DEBUG'))
    app.logger.setLevel(app.config.get('LOG_LEVEL', 'DEBUG'))
    app.logger.addHandler(handler)

    stream_handler = StreamHandler()
    stream_handler.setLevel(app.config.get('LOG_LEVEL', 'DEBUG'))
    app.logger.addHandler(stream_handler)

    if app.config.get('DEBUG_DUMP', False):
        activate_debug_dump()


def install_plugins(app):
    """
    Installs new issuers that are not currently bundled with Lemur.

    :param app:
    :return:
    """
    from lemur.plugins import plugins
    from lemur.plugins.base import register
    # entry_points={
    #    'lemur.plugins': [
    #         'verisign = lemur_verisign.plugin:VerisignPlugin'
    #     ],
    # },
    for ep in pkg_resources.iter_entry_points('lemur.plugins'):
        try:
            plugin = ep.load()
        except Exception:
            import traceback
            app.logger.error("Failed to load plugin %r:\n%s\n" % (ep.name, traceback.format_exc()))
        else:
            register(plugin)

    # ensure that we have some way to notify
    with app.app_context():
        slug = app.config.get("LEMUR_DEFAULT_NOTIFICATION_PLUGIN", "email-notification")
        try:
            plugins.get(slug)
        except KeyError:
            raise Exception("Unable to location notification plugin: {slug}. Ensure that "
                            "LEMUR_DEFAULT_NOTIFICATION_PLUGIN is set to a valid and installed notification plugin."
                            .format(slug=slug))