# 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 collections
import gc
import io
import json
import platform
import socket
import sys
import traceback
from debtcollector import removals
import jinja2
from oslo_utils import reflection
from oslo_utils import strutils
from oslo_utils import timeutils
import stevedore
import webob.dec
import webob.exc
import webob.response
try:
import greenlet
except ImportError:
greenlet = None
from oslo_middleware import base
from oslo_middleware.healthcheck import opts
def _find_objects(t):
return [o for o in gc.get_objects() if isinstance(o, t)]
def _expand_template(contents, params):
tpl = jinja2.Template(source=contents,
undefined=jinja2.StrictUndefined)
return tpl.render(**params)
class Healthcheck(base.ConfigurableMiddleware):
"""Healthcheck application used for monitoring.
It will respond 200 with "OK" as the body. Or a 503 with the reason as the
body if one of the backends reports an application issue.
This is useful for the following reasons:
* Load balancers can 'ping' this url to determine service availability.
* Provides an endpoint that is similar to 'mod_status' in apache which
can provide details (or no details, depending on if configured) about
the activity of the server.
* *(and more)*
Example requests/responses (**not** detailed mode)::
$ curl -i -X HEAD "http://0.0.0.0:8775/healthcheck"
HTTP/1.1 204 No Content
Content-Type: text/plain; charset=UTF-8
Content-Length: 0
Date: Fri, 11 Sep 2015 18:55:08 GMT
$ curl -i -X GET "http://0.0.0.0:8775/healthcheck"
HTTP/1.1 200 OK
Content-Type: text/plain; charset=UTF-8
Content-Length: 2
Date: Fri, 11 Sep 2015 18:55:43 GMT
OK
$ curl -X GET -i -H "Accept: application/json" "http://0.0.0.0:8775/healthcheck"
HTTP/1.0 200 OK
Date: Wed, 24 Aug 2016 06:09:58 GMT
Content-Type: application/json
Content-Length: 63
{
"detailed": false,
"reasons": [
"OK"
]
}
$ curl -X GET -i -H "Accept: text/html" "http://0.0.0.0:8775/healthcheck"
HTTP/1.0 200 OK
Date: Wed, 24 Aug 2016 06:10:42 GMT
Content-Type: text/html; charset=UTF-8
Content-Length: 239
Healthcheck Status
Result of 1 checks:
Example requests/responses (**detailed** mode)::
$ curl -X GET -i -H "Accept: application/json" "http://0.0.0.0:8775/healthcheck"
HTTP/1.0 200 OK
Date: Wed, 24 Aug 2016 06:11:59 GMT
Content-Type: application/json
Content-Length: 3480
{
"detailed": true,
"gc": {
"counts": [
293,
10,
5
],
"threshold": [
700,
10,
10
]
},
"greenthreads": [
...
],
"now": "2016-08-24 06:11:59.419267",
"platform": "Linux-4.2.0-27-generic-x86_64-with-Ubuntu-14.04-trusty",
"python_version": "2.7.6 (default, Jun 22 2015, 17:58:13) \\n[GCC 4.8.2]",
"reasons": [
{
"class": "HealthcheckResult",
"details": "Path '/tmp/dead' was not found",
"reason": "OK"
}
],
"threads": [
...
]
}
$ curl -X GET -i -H "Accept: text/html" "http://0.0.0.0:8775/healthcheck"
HTTP/1.0 200 OK
Date: Wed, 24 Aug 2016 06:36:07 GMT
Content-Type: text/html; charset=UTF-8
Content-Length: 6838
Healthcheck Status
Server status
Server hostname:...
Current time:2016-08-24 06:36:07.302559
Python version:2.7.6 (default, Jun 22 2015, 17:58:13)
[GCC 4.8.2]
Platform:Linux-4.2.0-27-generic-x86_64-with-Ubuntu-14.04-trusty
Garbage collector:
Counts:(77, 1, 6)
Thresholds:(700, 10, 10)
Result of 1 checks:
|
Kind
|
Reason
|
Details
|
| HealthcheckResult |
OK |
Path '/tmp/dead' was not found |
1 greenthread(s) active:
File "oslo_middleware/healthcheck/__main__.py", line 94, in <module>
main()
File "oslo_middleware/healthcheck/__main__.py", line 90, in main
server.serve_forever()
...
|
1 thread(s) active:
File "oslo_middleware/healthcheck/__main__.py", line 94, in <module>
main()
File "oslo_middleware/healthcheck/__main__.py", line 90, in main
server.serve_forever()
....
|
Example of paste configuration:
.. code-block:: ini
[app:healthcheck]
use = egg:oslo.middleware: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
[composite:public_api]
use = egg:Paste#urlmap
/ = public_api_pipeline
/healthcheck = healthcheck_public
[composite:admin_api]
use = egg:Paste#urlmap
/ = admin_api_pipeline
/healthcheck = healthcheck_admin
[pipeline:public_api_pipeline]
pipeline = sizelimit [...] public_service
[pipeline:admin_api_pipeline]
pipeline = sizelimit [...] admin_service
[app:healthcheck_public]
use = egg:oslo.middleware:healthcheck
backends = disable_by_file
disable_by_file_path = /var/run/nova/healthcheck_public_disable
[filter:healthcheck_admin]
use = egg:oslo.middleware:healthcheck
backends = disable_by_file
disable_by_file_path = /var/run/nova/healthcheck_admin_disable
"""
NAMESPACE = "oslo.middleware.healthcheck"
HEALTHY_TO_STATUS_CODES = {
True: webob.exc.HTTPOk.code,
False: webob.exc.HTTPServiceUnavailable.code,
}
HEAD_HEALTHY_TO_STATUS_CODES = {
True: webob.exc.HTTPNoContent.code,
False: webob.exc.HTTPServiceUnavailable.code,
}
PLAIN_RESPONSE_TEMPLATE = """
{% for reason in reasons %}
{% if reason %}{{reason}}{% endif -%}
{% endfor %}
"""
HTML_RESPONSE_TEMPLATE = """
Healthcheck Status
{% if detailed -%}
Server status
{% if hostname -%}
Server hostname:{{hostname|e}}
{%- endif %}
Current time:{{now|e}}
Python version:{{python_version|e}}
Platform:{{platform|e}}
Garbage collector:
Counts:{{gc.counts|e}}
Thresholds:{{gc.threshold|e}}
{%- endif %}
Result of {{results|length}} checks:
{% if detailed -%}
|
Kind
|
Reason
|
Details
|
{% else %}
Reason
|
{%- endif %}
{% for result in results -%}
{% if result.reason -%}
{% if detailed -%}
| {{result.class|e}} |
{%- endif %}
{{result.reason|e}} |
{% if detailed -%}
{{result.details|e}} |
{%- endif %}
{%- endif %}
{%- endfor %}
{% if detailed -%}
{% if greenthreads -%}
{{greenthreads|length}} greenthread(s) active:
{% for stack in greenthreads -%}
{{stack|e}} |
{%- endfor %}
{%- endif %}
{% if threads -%}
{{threads|length}} thread(s) active:
{% for stack in threads -%}
{{stack|e}} |
{%- endfor %}
{%- endif %}
{%- endif %}
"""
def __init__(self, *args, **kwargs):
super(Healthcheck, self).__init__(*args, **kwargs)
self.oslo_conf.register_opts(opts.HEALTHCHECK_OPTS,
group='healthcheck')
self._path = self._conf_get('path')
self._show_details = self._conf_get('detailed')
self._backends = stevedore.NamedExtensionManager(
self.NAMESPACE, self._conf_get('backends'),
name_order=True, invoke_on_load=True,
invoke_args=(self.oslo_conf, self.conf))
self._accept_to_functor = collections.OrderedDict([
# Order here matters...
('text/plain', self._make_text_response),
('text/html', self._make_html_response),
('application/json', self._make_json_response),
])
self._accept_order = tuple(self._accept_to_functor)
# When no accept type matches instead of returning 406 we will
# always return text/plain (because sending an error from this
# middleware actually can cause issues).
self._default_accept = 'text/plain'
self._ignore_path = False
def _conf_get(self, key, group='healthcheck'):
return super(Healthcheck, self)._conf_get(key, group=group)
@removals.remove(
message="The healthcheck middleware must now be configured as "
"an application, not as a filter")
@classmethod
def factory(cls, global_conf, **local_conf):
return super(Healthcheck, cls).factory(global_conf, **local_conf)
@classmethod
def app_factory(cls, global_conf, **local_conf):
"""Factory method for paste.deploy.
:param global_conf: dict of options for all middlewares
(usually the [DEFAULT] section of the paste deploy
configuration file)
:param local_conf: options dedicated to this middleware
(usually the option defined in the middleware
section of the paste deploy configuration file)
"""
conf = global_conf.copy() if global_conf else {}
conf.update(local_conf)
o = cls(application=None, conf=conf)
o._ignore_path = True
return o
@staticmethod
def _get_threadstacks():
threadstacks = []
try:
active_frames = sys._current_frames()
except AttributeError:
pass
else:
buf = io.StringIO()
for stack in active_frames.values():
traceback.print_stack(stack, file=buf)
threadstacks.append(buf.getvalue())
buf.seek(0)
buf.truncate()
return threadstacks
@staticmethod
def _get_greenstacks():
greenstacks = []
if greenlet is not None:
buf = io.StringIO()
for gt in _find_objects(greenlet.greenlet):
traceback.print_stack(gt.gr_frame, file=buf)
greenstacks.append(buf.getvalue())
buf.seek(0)
buf.truncate()
return greenstacks
@staticmethod
def _pretty_json_dumps(contents):
return json.dumps(contents, indent=4, sort_keys=True)
@staticmethod
def _are_results_healthy(results):
for result in results:
if not result.available:
return False
return True
def _make_text_response(self, results, healthy):
params = {
'reasons': [result.reason for result in results],
'detailed': self._show_details,
}
body = _expand_template(self.PLAIN_RESPONSE_TEMPLATE, params)
return (body.strip(), 'text/plain')
def _make_json_response(self, results, healthy):
if self._show_details:
body = {
'detailed': True,
'python_version': sys.version,
'now': str(timeutils.utcnow()),
'platform': platform.platform(),
'gc': {
'counts': gc.get_count(),
'threshold': gc.get_threshold(),
},
}
reasons = []
for result in results:
reasons.append({
'reason': result.reason,
'details': result.details or '',
'class': reflection.get_class_name(result,
fully_qualified=False),
})
body['reasons'] = reasons
body['greenthreads'] = self._get_greenstacks()
body['threads'] = self._get_threadstacks()
else:
body = {
'reasons': [result.reason for result in results],
'detailed': False,
}
return (self._pretty_json_dumps(body), 'application/json')
def _make_head_response(self, results, healthy):
return ( "", "text/plain")
def _make_html_response(self, results, healthy):
try:
hostname = socket.gethostname()
except socket.error:
hostname = None
translated_results = []
for result in results:
translated_results.append({
'details': result.details or '',
'reason': result.reason,
'class': reflection.get_class_name(result,
fully_qualified=False),
})
params = {
'healthy': healthy,
'hostname': hostname,
'results': translated_results,
'detailed': self._show_details,
'now': str(timeutils.utcnow()),
'python_version': sys.version,
'platform': platform.platform(),
'gc': {
'counts': gc.get_count(),
'threshold': gc.get_threshold(),
},
'threads': self._get_threadstacks(),
'greenthreads': self._get_threadstacks(),
}
body = _expand_template(self.HTML_RESPONSE_TEMPLATE, params)
return (body.strip(), 'text/html')
@webob.dec.wsgify
def process_request(self, req):
if not self._ignore_path and req.path != self._path:
return None
results = [ext.obj.healthcheck(req.server_port)
for ext in self._backends]
healthy = self._are_results_healthy(results)
if req.method == "HEAD":
functor = self._make_head_response
status = self.HEAD_HEALTHY_TO_STATUS_CODES[healthy]
else:
status = self.HEALTHY_TO_STATUS_CODES[healthy]
try:
offers = req.accept.acceptable_offers(self._accept_order)
accept_type = offers[0][0]
except IndexError:
accept_type = self._default_accept
functor = self._accept_to_functor[accept_type]
body, content_type = functor(results, healthy)
return webob.response.Response(status=status, body=body,
charset='UTF-8',
content_type=content_type)