Allow healthcheck to be configured by oslo.config

It is standard practice in oslo.middleware to allow configuration via
both the paste file and the oslo.config file. Projects such as keystone
don't allow shipping default configuration in the paste.ini files.

Use the configuration methods provided by the existing base middleware
to allow configuing via oslo.config and register the sample options
available for the middleware.

Closes-Bug: #1634329
Change-Id: I33b7b1f9d945280265eb3b712cb85a2d66616c17

6 files changed, 127 insertions, 26 deletions

diff --git a/oslo_middleware/healthcheck/__init__.py b/oslo_middleware/healthcheck/__init__.py
index ce2b03a..65c2791 100644
--- a/oslo_middleware/healthcheck/__init__.py
+++ b/oslo_middleware/healthcheck/__init__.py
@@ -37,6 +37,7 @@ except ImportError:
     greenlet = None
 
 from oslo_middleware import base
+from oslo_middleware.healthcheck import opts
 
 
 def _find_objects(t):
@@ -374,18 +375,16 @@ Reason
 </HTML>
 """
 
-    def __init__(self, application, conf):
-        super(Healthcheck, self).__init__(application)
-        self._path = conf.get('path', '/healthcheck')
-        self._show_details = strutils.bool_from_string(conf.get('detailed'))
-        self._backend_names = []
-        backends = conf.get('backends')
-        if backends:
-            self._backend_names = backends.split(',')
+    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._backend_names,
+            self.NAMESPACE, self._conf_get('backends'),
             name_order=True, invoke_on_load=True,
-            invoke_args=(conf,))
+            invoke_args=(self.oslo_conf, self.conf))
         self._accept_to_functor = collections.OrderedDict([
             # Order here matters...
             ('text/plain', self._make_text_response),
@@ -398,6 +397,9 @@ Reason
         # middleware actually can cause issues).
         self._default_accept = 'text/plain'
 
+    def _conf_get(self, key, group='healthcheck'):
+        return super(Healthcheck, self)._conf_get(key, group=group)
+
     @staticmethod
     def _get_threadstacks():
         threadstacks = []
diff --git a/oslo_middleware/healthcheck/disable_by_file.py b/oslo_middleware/healthcheck/disable_by_file.py
index 7fbb14b..1b3ffa3 100644
--- a/oslo_middleware/healthcheck/disable_by_file.py
+++ b/oslo_middleware/healthcheck/disable_by_file.py
@@ -17,6 +17,7 @@ import logging
 import os
 
 from oslo_middleware._i18n import _LW
+from oslo_middleware.healthcheck import opts
 from oslo_middleware.healthcheck import pluginbase
 
 LOG = logging.getLogger(__name__)
@@ -40,23 +41,25 @@ class DisableByFilesPortsHealthcheck(pluginbase.HealthcheckBaseExtension):
       disable_by_file_paths = 5000:/var/run/keystone/healthcheck_disable, \
             35357:/var/run/keystone/admin_healthcheck_disable
     """
-    def __init__(self, conf):
-        super(DisableByFilesPortsHealthcheck, self).__init__(conf)
+
+    def __init__(self, *args, **kwargs):
+        super(DisableByFilesPortsHealthcheck, self).__init__(*args, **kwargs)
+        self.oslo_conf.register_opts(opts.DISABLE_BY_FILES_OPTS,
+                                     group='healthcheck')
         self.status_files = {}
-        self.status_files.update(
-            self._iter_paths_ports(self.conf.get('disable_by_file_paths')))
+        paths = self._conf_get('disable_by_file_paths')
+        self.status_files.update(self._iter_paths_ports(paths))
 
     @staticmethod
     def _iter_paths_ports(paths):
-        if paths:
-            for port_path in paths.split(","):
-                port_path = port_path.strip()
-                if port_path:
-                    # On windows, drive letters are followed by colons,
-                    # which makes split() return 3 elements in this case
-                    port, path = port_path.split(":", 1)
-                    port = int(port)
-                    yield (port, path)
+        for port_path in paths:
+            port_path = port_path.strip()
+            if port_path:
+                # On windows, drive letters are followed by colons,
+                # which makes split() return 3 elements in this case
+                port, path = port_path.split(":", 1)
+                port = int(port)
+                yield (port, path)
 
     def healthcheck(self, server_port):
         path = self.status_files.get(server_port)
@@ -92,9 +95,14 @@ class DisableByFileHealthcheck(pluginbase.HealthcheckBaseExtension):
       disable_by_file_path = /var/run/nova/healthcheck_disable
     """
 
+    def __init__(self, *args, **kwargs):
+        super(DisableByFileHealthcheck, self).__init__(*args, **kwargs)
+        self.oslo_conf.register_opts(opts.DISABLE_BY_FILE_OPTS,
+                                     group='healthcheck')
+
     def healthcheck(self, server_port):
-        path = self.conf.get('disable_by_file_path')
-        if path is None:
+        path = self._conf_get('disable_by_file_path')
+        if not path:
             LOG.warning(_LW('DisableByFile healthcheck middleware enabled '
                             'without disable_by_file_path set'))
             return pluginbase.HealthcheckResult(
diff --git a/oslo_middleware/healthcheck/opts.py b/oslo_middleware/healthcheck/opts.py
new file mode 100644
index 0000000..d283f4d
--- /dev/null
+++ b/oslo_middleware/healthcheck/opts.py
@@ -0,0 +1,46 @@
+# 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.
+
+from oslo_config import cfg
+
+
+HEALTHCHECK_OPTS = [
+    cfg.StrOpt('path',
+               default='/healthcheck',
+               help='The path to respond to healtcheck requests on.'),
+    cfg.BoolOpt('detailed',
+                default=False,
+                help='Show more detailed information as part of the response'),
+    cfg.ListOpt('backends',
+                default=[],
+                help='Additional backends that can perform health checks and '
+                     'report that information back as part of a request.'),
+]
+
+
+DISABLE_BY_FILE_OPTS = [
+    cfg.StrOpt('disable_by_file_path',
+               default=None,
+               help='Check the presence of a file to determine if an '
+                    'application is running on a port. Used by '
+                    'DisableByFileHealthcheck plugin.'),
+]
+
+
+DISABLE_BY_FILES_OPTS = [
+    cfg.ListOpt('disable_by_file_paths',
+                default=[],
+                help='Check the presence of a file based on a port to '
+                     'determine if an application is running on a port. '
+                     'Expects a "port:path" list of strings. Used by '
+                     'DisableByFilesPortsHealthcheck plugin.'),
+]
diff --git a/oslo_middleware/healthcheck/pluginbase.py b/oslo_middleware/healthcheck/pluginbase.py
index e370967..eb8013d 100644
--- a/oslo_middleware/healthcheck/pluginbase.py
+++ b/oslo_middleware/healthcheck/pluginbase.py
@@ -29,7 +29,9 @@ class HealthcheckResult(object):
 
 @six.add_metaclass(abc.ABCMeta)
 class HealthcheckBaseExtension(object):
-    def __init__(self, conf):
+
+    def __init__(self, oslo_conf, conf):
+        self.oslo_conf = oslo_conf
         self.conf = conf
 
     @abc.abstractmethod
@@ -38,3 +40,10 @@ class HealthcheckBaseExtension(object):
 
         return: HealthcheckResult object
         """
+
+    def _conf_get(self, key, group='healthcheck'):
+        if key in self.conf:
+            # Validate value type
+            self.oslo_conf.set_override(key, self.conf[key], group=group,
+                                        enforce_type=True)
+        return getattr(getattr(self.oslo_conf, group), key)
diff --git a/oslo_middleware/opts.py b/oslo_middleware/opts.py
index e66e723..1584f9b 100644
--- a/oslo_middleware/opts.py
+++ b/oslo_middleware/opts.py
@@ -19,6 +19,7 @@ __all__ = [
     'list_opts_ssl',
     'list_opts_cors',
     'list_opts_http_proxy_to_wsgi',
+    'list_opts_healthcheck',
 ]
 
 
@@ -26,6 +27,7 @@ import copy
 import itertools
 
 from oslo_middleware import cors
+from oslo_middleware.healthcheck import opts as healthcheck_opts
 from oslo_middleware import http_proxy_to_wsgi
 from oslo_middleware import sizelimit
 from oslo_middleware import ssl
@@ -56,6 +58,7 @@ def list_opts():
             list_opts_ssl(),
             list_opts_cors(),
             list_opts_http_proxy_to_wsgi(),
+            list_opts_healthcheck(),
         )
     )
 
@@ -155,3 +158,31 @@ def list_opts_http_proxy_to_wsgi():
     return [
         ('oslo_middleware', copy.deepcopy(http_proxy_to_wsgi.OPTS)),
     ]
+
+
+def list_opts_healthcheck():
+    """Return a list of oslo.config options for healthcheck.
+
+    The returned list includes all oslo.config options which may be registered
+    at runtime by the library.
+
+    Each element of the list is a tuple. The first element is the name of the
+    group under which the list of elements in the second element will be
+    registered. A group name of None corresponds to the [DEFAULT] group in
+    config files.
+
+    This function is also discoverable via the 'oslo.middleware' entry point
+    under the 'oslo.config.opts' namespace.
+
+    The purpose of this is to allow tools like the Oslo sample config file
+    generator to discover the options exposed to users by this library.
+
+    :returns: a list of (group_name, opts) tuples
+    """
+    # standard opts and the most common plugin to turn up in sample config.
+    # can figure out a better way of exposing plugin opts later if required.
+    return [
+        ('healthcheck', copy.deepcopy(healthcheck_opts.HEALTHCHECK_OPTS +
+                                      healthcheck_opts.DISABLE_BY_FILE_OPTS +
+                                      healthcheck_opts.DISABLE_BY_FILES_OPTS))
+    ]
diff --git a/oslo_middleware/tests/test_healthcheck.py b/oslo_middleware/tests/test_healthcheck.py
index df73969..793a895 100644
--- a/oslo_middleware/tests/test_healthcheck.py
+++ b/oslo_middleware/tests/test_healthcheck.py
@@ -17,6 +17,7 @@ import threading
 import time
 
 import mock
+from oslo_config import fixture as config
 from oslotest import base as test_base
 import requests
 import webob.dec
@@ -50,6 +51,10 @@ class HealthcheckMainTests(test_base.BaseTestCase):
 
 class HealthcheckTests(test_base.BaseTestCase):
 
+    def setUp(self):
+        super(HealthcheckTests, self).setUp()
+        self.useFixture(config.Config())
+
     @staticmethod
     @webob.dec.wsgify
     def application(req):