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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
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#
#   http://www.apache.org/licenses/LICENSE-2.0
#
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# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

"""Serve logs process"""
import logging
import os

import gunicorn.app.base
from flask import Flask, abort, request, send_from_directory
from jwt.exceptions import (
    ExpiredSignatureError,
    ImmatureSignatureError,
    InvalidAudienceError,
    InvalidIssuedAtError,
    InvalidSignatureError,
)
from setproctitle import setproctitle

from airflow.configuration import conf
from airflow.utils.docs import get_docs_url
from airflow.utils.jwt_signer import JWTSigner

logger = logging.getLogger(__name__)


def create_app():
    flask_app = Flask(__name__, static_folder=None)
    expiration_time_in_seconds = conf.getint('webserver', 'log_request_clock_grace', fallback=30)
    log_directory = os.path.expanduser(conf.get('logging', 'BASE_LOG_FOLDER'))

    signer = JWTSigner(
        secret_key=conf.get('webserver', 'secret_key'),
        expiration_time_in_seconds=expiration_time_in_seconds,
        audience="task-instance-logs",
    )

    # Prevent direct access to the logs port
    @flask_app.before_request
    def validate_pre_signed_url():
        try:
            auth = request.headers.get('Authorization')
            if auth is None:
                logger.warning("The Authorization header is missing: %s.", request.headers)
                abort(403)
            payload = signer.verify_token(auth)
            token_filename = payload.get("filename")
            request_filename = request.view_args['filename']
            if token_filename is None:
                logger.warning("The payload does not contain 'filename' key: %s.", payload)
                abort(403)
            if token_filename != request_filename:
                logger.warning(
                    "The payload log_relative_path key is different than the one in token:"
                    "Request path: %s. Token path: %s.",
                    request_filename,
                    token_filename,
                )
                abort(403)
        except InvalidAudienceError:
            logger.warning("Invalid audience for the request", exc_info=True)
            abort(403)
        except InvalidSignatureError:
            logger.warning("The signature of the request was wrong", exc_info=True)
            abort(403)
        except ImmatureSignatureError:
            logger.warning("The signature of the request was sent from the future", exc_info=True)
            abort(403)
        except ExpiredSignatureError:
            logger.warning(
                "The signature of the request has expired. Make sure that all components "
                "in your system have synchronized clocks. "
                "See more at %s",
                get_docs_url("configurations-ref.html#secret-key"),
                exc_info=True,
            )
            abort(403)
        except InvalidIssuedAtError:
            logger.warning(
                "The request was issues in the future. Make sure that all components "
                "in your system have synchronized clocks. "
                "See more at %s",
                get_docs_url("configurations-ref.html#secret-key"),
                exc_info=True,
            )
            abort(403)
        except Exception:
            logger.warning("Unknown error", exc_info=True)
            abort(403)

    @flask_app.route('/log/<path:filename>')
    def serve_logs_view(filename):
        return send_from_directory(log_directory, filename, mimetype="application/json", as_attachment=False)

    return flask_app


class StandaloneGunicornApplication(gunicorn.app.base.BaseApplication):
    """
    Standalone Gunicorn application/serve for usage with any WSGI-application.

    Code inspired by an example from the Gunicorn documentation.
    https://github.com/benoitc/gunicorn/blob/cf55d2cec277f220ebd605989ce78ad1bb553c46/examples/standalone_app.py

    For details, about standalone gunicorn application, see:
    https://docs.gunicorn.org/en/stable/custom.html
    """

    def __init__(self, app, options=None):
        self.options = options or {}
        self.application = app
        super().__init__()

    def load_config(self):
        for key, value in self.options.items():
            self.cfg.set(key.lower(), value)

    def load(self):
        return self.application


def serve_logs():
    """Serves logs generated by Worker"""
    setproctitle("airflow serve-logs")
    wsgi_app = create_app()

    worker_log_server_port = conf.getint('logging', 'WORKER_LOG_SERVER_PORT')
    options = {
        'bind': f"0.0.0.0:{worker_log_server_port}",
        'workers': 2,
    }
    StandaloneGunicornApplication(wsgi_app, options).run()


if __name__ == '__main__':
    serve_logs()
