Add a enabled by files healthcheck plugin

Implements: blueprint enable-by-files-healthcheck
Change-Id: Ia8a54cbd38f2faf70bbe91032da36448f2fa2de7

doc/source/reference/healthcheck_plugins.rst

@@ -8,6 +8,9 @@
 .. automodule:: oslo_middleware.healthcheck.disable_by_file
    :members:
 
+.. automodule:: oslo_middleware.healthcheck.enable_by_files
+   :members:
+
 
 Available Plugins
 ------------------

oslo_middleware/healthcheck/__init__.py

@@ -39,6 +39,7 @@ except ImportError:
     greenlet = None
 
 from oslo_middleware import base
+from oslo_middleware.basic_auth import ConfigInvalid
 from oslo_middleware.healthcheck import opts
 
 
@@ -397,6 +398,11 @@ Reason
             for r in self._conf_get('allowed_source_ranges')]
         self._ignore_proxied_requests = self._conf_get(
             'ignore_proxied_requests')
+
+        # (abhishekk): Verify that if `enable_by_files` and
+        # `disable_by_file` backends are not enabled at same time.
+        self._verify_configured_plugins()
+
         self._backends = stevedore.NamedExtensionManager(
             self.NAMESPACE, self._conf_get('backends'),
             name_order=True, invoke_on_load=True,
@@ -414,6 +420,16 @@ Reason
         self._default_accept = 'text/plain'
         self._ignore_path = False
 
+    def _verify_configured_plugins(self):
+        backends = self._conf_get('backends')
+        desired_plugins = ['disable_by_file', 'enable_by_files']
+
+        if set(desired_plugins).issubset(set(backends)):
+            raise ConfigInvalid('`enable_by_files` and `disable_by_file`'
+                                ' healthcheck middleware should not be '
+                                'configured at once.')
+
+
     def _conf_get(self, key, group='healthcheck'):
         return super(Healthcheck, self)._conf_get(key, group=group)
 

oslo_middleware/healthcheck/enable_by_files.py

@@ -0,0 +1,60 @@
+# Copyright 2024 Red Hat.
+# 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 logging
+import os
+
+from oslo_middleware.healthcheck import opts
+from oslo_middleware.healthcheck import pluginbase
+
+LOG = logging.getLogger(__name__)
+
+
+class EnableByFilesHealthcheck(pluginbase.HealthcheckBaseExtension):
+    """EnableByFilesHealthcheck healthcheck middleware plugin
+
+    This plugin checks presence of a file at a specified location.
+
+    Example of middleware configuration:
+
+    .. code-block:: ini
+
+      [app:healthcheck]
+      paste.app_factory = oslo_middleware:Healthcheck.app_factory
+      path = /healthcheck
+      backends = enable_by_files
+      enable_by_file_paths = /var/lib/glance/images/.marker,
+          /var/lib/glance/os_glance_staging_store/.marker
+      # set to True to enable detailed output, False is the default
+      detailed = False
+    """
+
+    def __init__(self, *args, **kwargs):
+        super(EnableByFilesHealthcheck, self).__init__(*args, **kwargs)
+        self.oslo_conf.register_opts(opts.ENABLE_BY_FILES_OPTS,
+                                     group='healthcheck')
+        self.file_paths = self._conf_get('enable_by_file_paths')
+
+    def healthcheck(self, server_port):
+        for file_path in self.file_paths:
+            if not os.path.exists(file_path):
+                LOG.warning('EnableByFiles healthcheck middleware: Path %s '
+                            'is not present', file_path)
+                return pluginbase.HealthcheckResult(
+                    available=False, reason="FILE PATH MISSING",
+                    details='File path %s is missing' % file_path)
+        return pluginbase.HealthcheckResult(
+            available=True, reason="OK",
+            details='Specified file paths are available')

oslo_middleware/healthcheck/opts.py

@@ -57,3 +57,11 @@ DISABLE_BY_FILES_OPTS = [
                      'Expects a "port:path" list of strings. Used by '
                      'DisableByFilesPortsHealthcheck plugin.'),
 ]
+
+
+ENABLE_BY_FILES_OPTS = [
+    cfg.ListOpt('enable_by_file_paths',
+                default=[],
+                help='Check the presence of files. Used by '
+                     'EnableByFilesHealthcheck plugin.'),
+]

oslo_middleware/opts.py

@@ -157,7 +157,8 @@ def list_opts_healthcheck():
     return [
         ('healthcheck', copy.deepcopy(healthcheck_opts.HEALTHCHECK_OPTS +
                                       healthcheck_opts.DISABLE_BY_FILE_OPTS +
-                                      healthcheck_opts.DISABLE_BY_FILES_OPTS))
+                                      healthcheck_opts.DISABLE_BY_FILES_OPTS +
+                                      healthcheck_opts.ENABLE_BY_FILES_OPTS))
     ]
 
 

oslo_middleware/tests/test_entry_points.py

@@ -35,3 +35,17 @@ class TestPasteDeploymentEntryPoints(base.BaseTestCase):
         factory_names = [extension.name for extension in em]
         self.assertThat(factory_names,
                         matchers.ContainsAll(factory_classes))
+
+    def test_healthcheck_entry_points(self):
+        healthcheck_plugins = {
+            'disable_by_file': 'DisableByFileHealthcheck',
+            'disable_by_files_ports': 'DisableByFilesPortsHealthcheck',
+            'enable_by_files': 'EnableByFilesHealthcheck'
+        }
+
+        em = stevedore.ExtensionManager('oslo.middleware.healthcheck')
+
+        # Ensure all the healthcheck plugins are defined by their names
+        plugin_names = [extension.name for extension in em]
+        self.assertThat(plugin_names,
+                        matchers.ContainsAll(healthcheck_plugins))

oslo_middleware/tests/test_healthcheck.py

@@ -24,6 +24,7 @@ import requests
 import webob.dec
 import webob.exc
 
+from oslo_middleware.basic_auth import ConfigInvalid
 from oslo_middleware import healthcheck
 from oslo_middleware.healthcheck import __main__
 
@@ -201,6 +202,63 @@ class HealthcheckTests(test_base.BaseTestCase):
                       server_port=81)
         self.assertIn('disable_by_files_ports', self.app._backends.names())
 
+    def test_enablefile_disablefile_configured(self):
+        conf = {'backends': 'disable_by_file,enable_by_files'}
+        self.assertRaises(ConfigInvalid,
+                          healthcheck.Healthcheck, self.application, conf)
+
+    def test_enablefile_unconfigured(self):
+        conf = {'backends': 'enable_by_files'}
+        self._do_test(conf, expected_body=b'OK')
+        self.assertIn('enable_by_files', self.app._backends.names())
+
+    def test_enablefile_enabled(self):
+        filename = self.create_tempfiles([('.test', '.foobar')])[0]
+        conf = {'backends': 'enable_by_files',
+                'enable_by_file_paths': filename}
+        self._do_test(conf, expected_body=b'OK')
+        self.assertIn('enable_by_files', self.app._backends.names())
+
+    def test_enablefile_enabled_head(self):
+        filename = self.create_tempfiles([('.test', '.foobar')])[0]
+        conf = {'backends': 'enable_by_files',
+                'enable_by_file_paths': filename}
+        self._do_test(conf, expected_body=b'', method='HEAD',
+                      expected_code=webob.exc.HTTPNoContent.code)
+
+    def test_enablefile_enabled_html_detailed(self):
+        filename = self.create_tempfiles([('.test', '.foobar')])[0]
+        conf = {'backends': 'enable_by_files',
+                'enable_by_file_paths': filename, 'detailed': True}
+        res = self._do_test_request(conf, accept="text/html")
+        self.assertIn(b'Result of 1 checks:', res.body)
+        self.assertIn(b'<TD>OK</TD>', res.body)
+        self.assertEqual(webob.exc.HTTPOk.code, res.status_int)
+
+    def test_enablefile_disabled(self):
+        conf = {'backends': 'enable_by_files',
+                'enable_by_file_paths': '.foobar'}
+        self._do_test(conf,
+                      expected_code=webob.exc.HTTPServiceUnavailable.code,
+                      expected_body=b'FILE PATH MISSING')
+        self.assertIn('enable_by_files', self.app._backends.names())
+
+    def test_enablefile_disabled_head(self):
+        conf = {'backends': 'enable_by_files',
+                'enable_by_file_paths': '.foobar'}
+        self._do_test(conf,
+                      expected_code=webob.exc.HTTPServiceUnavailable.code,
+                      expected_body=b'', method='HEAD')
+        self.assertIn('enable_by_files', self.app._backends.names())
+
+    def test_enablefile_disabled_html_detailed(self):
+        conf = {'backends': 'enable_by_files',
+                'enable_by_file_paths': '.foobar', 'detailed': True}
+        res = self._do_test_request(conf, accept="text/html")
+        self.assertIn(b'<TD>FILE PATH MISSING</TD>', res.body)
+        self.assertEqual(webob.exc.HTTPServiceUnavailable.code,
+                         res.status_int)
+
     def test_json_response(self):
         expected_body = jsonutils.dumps({'detailed': False, 'reasons': []},
                                         indent=4,

releasenotes/notes/enable-by-files-healthcheck-29938e3d6b8e5730.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    The new ``enable_by_files`` healthcheck plugin has been added.
+    This plugin will help to check whether specified file paths in
+    ``[healthcheck] enable_by_file_paths`` are present or not.

setup.cfg

@@ -38,6 +38,7 @@ oslo.config.opts =
 oslo.middleware.healthcheck =
     disable_by_file = oslo_middleware.healthcheck.disable_by_file:DisableByFileHealthcheck
     disable_by_files_ports = oslo_middleware.healthcheck.disable_by_file:DisableByFilesPortsHealthcheck
+    enable_by_files = oslo_middleware.healthcheck.enable_by_files:EnableByFilesHealthcheck
 
 paste.app_factory =
     healthcheck = oslo_middleware:Healthcheck.app_factory