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Make /healthcheck cache results

The healthcheck endpoint should cache results to reduce the potential load on the backend systems being tested.
This patch adds the caching and a configuration setting for the interval
between cache refreshes.

Change-Id: Ic97a991437144f3a220d9b96839cec5b63565f8c
Story: 2008203
Task: 40987
changes/14/754614/3
Michael Johnson 1 year ago
parent
commit
6c54eab5b5
  1. 19
      doc/source/admin/healthcheck.rst
  2. 3
      etc/octavia.conf
  3. 23
      octavia/api/healthcheck/healthcheck_plugins.py
  4. 3
      octavia/common/config.py
  5. 9
      octavia/tests/functional/api/test_healthcheck.py
  6. 5
      releasenotes/notes/healthcheck-cache-641f0a64e6f5856c.yaml

19
doc/source/admin/healthcheck.rst

@ -527,6 +527,25 @@ You will then need to select the desired monitoring backend plugins:
changes. Not only does it not run any tests, it will return 204 results
instead of 200.
The Octavia API health monitoring endpoint does not require a keystone token
for access to allow external load balancers to query the endpoint. For this
reason we recommend you restrict access to it on your external load balancer
to prevent abuse.
As an additional protection, the API will cache results for a configurable
period of time. This means that queries to the health monitoring endpoint
will return cached results until the refresh interval has expired, at which
point the health check plugin will rerun the check.
By default, the refresh interval is five seconds. This can be configured by
adjusting the healthcheck_refresh_interval setting in the Octavia configuration
file:
.. code-block:: ini
[api_settings]
healthcheck_refresh_interval = 5
Optionally you can enable the "detailed" mode in Oslo middleware healthcheck.
This will cause Oslo middleware healthcheck to return additional information
about the API instance. It will also provide exception details if one was

3
etc/octavia.conf

@ -56,6 +56,9 @@
# Boolean to enable/disable oslo middleware /healthcheck in the Octavia API
# healthcheck_enabled = False
# The interval healthcheck plugins should cache results, in seconds.
# healthcheck_refresh_interval = 5
# Default cipher string for new TLS-terminated listeners
# Cipher strings are in OpenSSL format, see https://www.openssl.org/docs/man1.1.1/man1/ciphers.html
# This example is the "Broad Compatibility" cipher string from OWASP,

23
octavia/api/healthcheck/healthcheck_plugins.py

@ -11,23 +11,42 @@
# 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 datetime
from oslo_config import cfg
from oslo_middleware.healthcheck import pluginbase
from octavia.db import api as db_apis
from octavia.db import healthcheck
CONF = cfg.CONF
class OctaviaDBHealthcheck(pluginbase.HealthcheckBaseExtension):
UNAVAILABLE_REASON = 'The Octavia database is unavailable.'
last_check = None
last_result = None
last_message = None
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
def healthcheck(self, server_port):
try:
result, message = healthcheck.check_database_connection(
db_apis.get_session())
if (self.last_check is not None and
((datetime.datetime.now() -
self.last_check).total_seconds()) <
CONF.api_settings.healthcheck_refresh_interval):
result = self.last_result
message = self.last_message
else:
result, message = healthcheck.check_database_connection(
db_apis.get_session())
self.last_check = datetime.datetime.now()
self.last_result = result
self.last_message = message
if result:
return OctaviaDBCheckResult(available=True, reason="OK")
else:

3
octavia/common/config.py

@ -106,6 +106,9 @@ api_opts = [
cfg.BoolOpt('healthcheck_enabled', default=False,
help=_("When True, the oslo middleware healthcheck endpoint "
"is enabled in the Octavia API.")),
cfg.IntOpt('healthcheck_refresh_interval', default=5,
help=_("The interval healthcheck plugins should cache results, "
"in seconds.")),
cfg.StrOpt('default_listener_ciphers',
default=constants.CIPHERS_OWASP_SUITE_B,
help=_("Default OpenSSL cipher string (colon-separated) for "

9
octavia/tests/functional/api/test_healthcheck.py

@ -49,6 +49,7 @@ class TestHealthCheck(base_db_test.OctaviaDBTestBase):
self.conf = self.useFixture(oslo_fixture.Config(cfg.CONF))
self.conf.config(group='healthcheck', backends=['octavia_db_check'])
self.conf.config(group='api_settings', healthcheck_refresh_interval=5)
self.UNAVAILABLE = (healthcheck_plugins.OctaviaDBHealthcheck.
UNAVAILABLE_REASON)
@ -145,6 +146,14 @@ class TestHealthCheck(base_db_test.OctaviaDBTestBase):
self.assertIn('OK', response.text)
self.assertIn('Garbage collector', response.text)
def test_healthcheck_get_text_cached(self):
self.conf.config(group='healthcheck', detailed=False)
app = self._get_enabled_app()
for i in range(10):
response = self._get(app, '/healthcheck')
self.assertEqual(200, response.status_code)
self.assertEqual('OK', response.text)
def test_healthcheck_disabled_get(self):
self._get(self._get_disabled_app(), '/healthcheck', status=404)

5
releasenotes/notes/healthcheck-cache-641f0a64e6f5856c.yaml

@ -0,0 +1,5 @@
---
fixes:
- |
Fixed the healthcheck endpoint always querying the backends by caching
results for a configurable time. The default is five seconds.
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