Source code for google.appengine.api.backends.backends

#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# 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.
#



"""Backends API.

.. deprecated:: 1.9.1
   Use Modules library instead.

This API provides utility methods for working with backends.
"""










import logging
import os
import re

from google.appengine.api import app_identity
from google.appengine.api import modules

[docs]class Error(Exception): """Base class for exceptions in this module."""
[docs]class DefaultHostnameError(Error): """Raised if no default hostname is set in the environment."""
[docs]class InvalidBackendError(Error): """Raised if an invalid backend was provided.""" pass
[docs]class InvalidInstanceError(Error): """Raised if an invalid instance was provided.""" pass
logging.warning('The Backends API is deprecated and will be removed in a ' 'future release. Please migrate to the Modules API as soon as ' 'possible.')
[docs]def get_backend(): """DEPRECATED: Get the name of the backend handling this request. Warning: This API is deprecated and will be removed in a future release. Please migrate to the Modules API as soon as possible. Returns: string: The current backend, or None if this is not a backend. """ return os.environ.get('BACKEND_ID', None)
[docs]def get_instance(): """DEPRECATED: Get the instance number of the backend handling this request. Warning: This API is deprecated and will be removed in a future release. Please migrate to the Modules API as soon as possible. Returns: int: The instance, in [0, instances-1], or None if this is not a backend. """ instance = os.environ.get('INSTANCE_ID', None) if instance is not None: return int(instance) else: return None
[docs]def get_url(backend=None, instance=None, protocol='http'): """DEPRECATED: Returns a URL pointing to a backend or backend instance. Warning: This API is deprecated and will be removed in a future release. Please migrate to the Modules API as soon as possible. This method works in both production and development environments. Args: backend: The name of the backend. If None, the current backend will be used. instance: An optoinal instance number. If provided, the URL will target the specific instance. If absent, the URL will point to a load-balancing hostname for the backend. protocol: The protocol to use (default='http'). Raises: InvalidBackendError InvalidInstanceError Returns: The URL of the backend or backend instance. """ if backend is None: backend = get_backend() if _is_dev2_environment(): return _get_dev2_url(backend, instance) elif _is_dev_environment(): return _get_dev_url(backend, instance) hostname = get_hostname(backend, instance) return '%s://%s' % (protocol, hostname)
[docs]def get_hostname(backend=None, instance=None): """DEPRECATED: Returns the hostname for a backend or backend instance. Warning: This API is deprecated and will be removed in a future release. Please migrate to the Modules API as soon as possible. Args: backend: The name of the backend. If None, the current backend will be used. instance: An optoinal instance number. If provided, the hostname will represent the specific instance. If absent, the hostname will represent the backend as a whole. Raises: InvalidBackendError InvalidInstanceError Returns: The hostname of the backend or backend instance. """ if backend is None: backend = get_backend() if not isinstance(backend, (str, unicode)): raise InvalidBackendError('Invalid backend: %s' % backend) if not re.match('^[a-zA-Z0-9\-]+$', backend): raise InvalidBackendError('Invalid backend: %s' % backend) if instance is not None: try: instance = int(instance) except ValueError: raise InvalidInstanceError('instance must be an integer.') if _is_dev2_environment(): return _get_dev2_hostname(backend, instance) elif _is_dev_environment(): return _get_dev_hostname(backend, instance) hostname = app_identity.get_default_version_hostname() if hostname is None: raise DefaultHostnameError hostname = '%s.%s' % (backend, hostname) if instance is not None: hostname = '%d.%s' % (instance, hostname) return hostname
def _is_dev2_environment(): """Indicates whether this code is being run in devappserver2.""" return os.environ.get('SERVER_SOFTWARE', '') == 'Development/2.0' def _get_dev2_url(backend, instance=None): """Returns the url of a backend [instance] in devappserver2. Args: backend: The name of the backend. instance: The backend instance number, in [0, instances-1]. Returns: The url of the backend. """ return 'http://%s' % _get_dev2_hostname(backend, instance) def _get_dev2_hostname(backend, instance=None): """Returns the hostname of a backend [instance] in devappserver2. Args: backend: The name of the backend. instance: The backend instance number, in [0, instances-1]. Returns: The hostname of the backend. """ try: return modules.get_hostname(module=backend, instance=instance) except modules.InvalidModuleError: raise InvalidBackendError() except modules.InvalidInstancesError: raise InvalidInstanceError() def _is_dev_environment(): """Indicates whether this code is being run in the development environment.""" return os.environ.get('SERVER_SOFTWARE', '').startswith('Development') def _get_dev_url(backend, instance=None): """Returns the url of a backend [instance] in the dev_appserver. Args: backend: The name of the backend. instance: The backend instance number, in [0, instances-1]. Returns: The url of the backend. """ return 'http://%s' % _get_dev_hostname(backend, instance) def _get_dev_hostname(backend, instance=None): """Returns the hostname of a backend [instance] in the dev_appserver. Args: backend: The name of the backend. instance: The backend instance number, in [0, instances-1]. Returns: The hostname of the backend. """ port = _get_dev_port(backend, instance) if not port: error = 'Backend not found: %s' % backend if instance is not None: error = '%s.%d' % (error, instance) raise InvalidBackendError(error) host = os.environ.get('SERVER_NAME', 'localhost') return '%s:%d' % (host, port) def _get_dev_port(backend, instance=None): """Returns the port for a backend [instance] in the dev_appserver. Args: backend: The name of the backend. instance: The backend instance (optional). Returns: int: The backend port. """ port = os.environ.get(_get_dev_port_var(backend, instance), None) if port: return int(port) else: return None def _set_dev_port(port, backend, instance=None, env=os.environ): """Sets the port for a backend [instance] in the dev_appserver. Args: port: The port. backend: The name of the backend. instance: The backend instance (optional). env: The environment in which to set the port. """ env[_get_dev_port_var(backend, instance)] = str(port) def _get_dev_port_var(backend, instance=None): """Return the environment variable for a backend port. Backend ports are stored at GET_PORT_<backend> for backends and GET_PORT_<backend>.<instance> for individual instances. Args: backend: The name of the backend. instance: The backend instance (optional). Returns: string: The environment variable where the backend port is stored. """ port_var = 'BACKEND_PORT.%s' % str(backend).lower() if instance is not None: port_var = '%s.%d' % (port_var, instance) return port_var

Send feedback about...

App Engine standard environment for Python