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# Copyright 2011 OpenStack Foundation.
# All Rights Reserved.
#
# 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.
import stevedore
import webob.dec
import webob.exc
import webob.response
from oslo_middleware import base
class Healthcheck(base.ConfigurableMiddleware):
"""Healthcheck middleware used for monitoring.
If the path is /healthcheck, it will respond 200 with "OK" as the body.
Or 503 with the reason as the body if one of the backend report
an application issue.
Example of paste configuration:
.. code-block:: ini
[filter:healthcheck]
paste.filter_factory = oslo_middleware:Healthcheck.factory
path = /healthcheck
backends = disable_by_file
disable_by_file_path = /var/run/nova/healthcheck_disable
[pipeline:public_api]
pipeline = healthcheck sizelimit [...] public_service
Multiple filter sections can be defined if it desired to have
pipelines with different healthcheck configuration, example:
.. code-block:: ini
[pipeline:public_api]
pipeline = healthcheck_public sizelimit [...] public_service
[pipeline:admin_api]
pipeline = healthcheck_admin sizelimit [...] admin_service
[filter:healthcheck_public]
paste.filter_factory = oslo_middleware:Healthcheck.factory
path = /healthcheck_public
backends = disable_by_file
disable_by_file_path = /var/run/nova/healthcheck_public_disable
[filter:healthcheck_admin]
paste.filter_factory = oslo_middleware:Healthcheck.factory
path = /healthcheck_admin
backends = disable_by_file
disable_by_file_path = /var/run/nova/healthcheck_admin_disable
More details on available backends and their configuration can be found
on this page: :doc:`healthcheck_plugins`.
"""
NAMESPACE = "oslo.middleware.healthcheck"
def __init__(self, application, conf):
super(Healthcheck, self).__init__(application)
self._path = conf.get('path', '/healthcheck')
self._backend_names = []
backends = conf.get('backends')
if backends:
self._backend_names = backends.split(',')
self._backends = stevedore.NamedExtensionManager(
self.NAMESPACE, self._backend_names,
name_order=True, invoke_on_load=True,
invoke_args=(conf,))
@webob.dec.wsgify
def process_request(self, req):
if req.path != self._path:
return None
healthy = True
reasons = []
for ext in self._backends:
result = ext.obj.healthcheck()
healthy &= result.available
if result.reason:
reasons.append(result.reason)
return webob.response.Response(
status=(webob.exc.HTTPOk.code if healthy
else webob.exc.HTTPServiceUnavailable.code),
body='\n'.join(reasons),
content_type="text/plain",
)
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