_helpers.py

# Copyright 2016 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "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.

"""Common logging helpers."""

import logging

from datetime import datetime
from datetime import timedelta
from datetime import timezone

import requests

from google.cloud.logging.entries import LogEntry
from google.cloud.logging.entries import ProtobufEntry
from google.cloud.logging.entries import StructEntry
from google.cloud.logging.entries import TextEntry

try:
    from google.cloud.logging_v2.gapic.enums import LogSeverity
except ImportError:  # pragma: NO COVER

    class LogSeverity(object):
        """Map severities for non-GAPIC usage."""

        DEFAULT = 0
        DEBUG = 100
        INFO = 200
        NOTICE = 300
        WARNING = 400
        ERROR = 500
        CRITICAL = 600
        ALERT = 700
        EMERGENCY = 800


_NORMALIZED_SEVERITIES = {
    logging.CRITICAL: LogSeverity.CRITICAL,
    logging.ERROR: LogSeverity.ERROR,
    logging.WARNING: LogSeverity.WARNING,
    logging.INFO: LogSeverity.INFO,
    logging.DEBUG: LogSeverity.DEBUG,
    logging.NOTSET: LogSeverity.DEFAULT,
}

_TIME_FORMAT = "%Y-%m-%dT%H:%M:%S.%f%z"
"""Time format for timestamps used in API"""

METADATA_URL = "http://metadata.google.internal./computeMetadata/v1/"
METADATA_HEADERS = {"Metadata-Flavor": "Google"}


def entry_from_resource(resource, client, loggers):
    """Detect correct entry type from resource and instantiate.

    :type resource: dict
    :param resource: One entry resource from API response.

    :type client: :class:`~google.cloud.logging.client.Client`
    :param client: Client that owns the log entry.

    :type loggers: dict
    :param loggers:
        A mapping of logger fullnames -> loggers.  If the logger
        that owns the entry is not in ``loggers``, the entry
        will have a newly-created logger.

    :rtype: :class:`~google.cloud.logging.entries._BaseEntry`
    :returns: The entry instance, constructed via the resource
    """
    if "textPayload" in resource:
        return TextEntry.from_api_repr(resource, client, loggers)

    if "jsonPayload" in resource:
        return StructEntry.from_api_repr(resource, client, loggers)

    if "protoPayload" in resource:
        return ProtobufEntry.from_api_repr(resource, client, loggers)

    return LogEntry.from_api_repr(resource, client, loggers)


def retrieve_metadata_server(metadata_key):
    """Retrieve the metadata key in the metadata server.

    See: https://cloud.google.com/compute/docs/storing-retrieving-metadata

    :type metadata_key: str
    :param metadata_key: Key of the metadata which will form the url. You can
                         also supply query parameters after the metadata key.
                         e.g. "tags?alt=json"

    :rtype: str
    :returns: The value of the metadata key returned by the metadata server.
    """
    url = METADATA_URL + metadata_key

    try:
        response = requests.get(url, headers=METADATA_HEADERS)

        if response.status_code == requests.codes.ok:
            return response.text

    except requests.exceptions.RequestException:
        # Ignore the exception, connection failed means the attribute does not
        # exist in the metadata server.
        pass

    return None


def _normalize_severity(stdlib_level):
    """Normalize a Python stdlib severity to LogSeverity enum.

    :type stdlib_level: int
    :param stdlib_level: 'levelno' from a :class:`logging.LogRecord`

    :rtype: int
    :returns: Corresponding Stackdriver severity.
    """
    return _NORMALIZED_SEVERITIES.get(stdlib_level, stdlib_level)


def _add_defaults_to_filter(filter_):
    """Modify the input filter expression to add sensible defaults.

    :type filter_: str
    :param filter_: The original filter expression

    :rtype: str
    :returns: sensible default filter string
    """

    # By default, requests should only return logs in the last 24 hours
    yesterday = datetime.now(timezone.utc) - timedelta(days=1)
    time_filter = 'timestamp>="%s"' % yesterday.strftime(_TIME_FORMAT)
    if filter_ is None:
        filter_ = time_filter
    elif "timestamp" not in filter_.lower():
        filter_ = "%s AND %s" % (filter_, time_filter)
    return filter_