Allow health check results to provide there own details

When in detailed mode, show the provided details in a nicely
formatted table (or json) so that the user of the healthcheck
middleware can gain more insight into the result that was
produced.

Change-Id: I2fc1f7588ee628990d78b15ad337bd0eebbe8fb3

3 files changed, 40 insertions, 9 deletions

diff --git a/oslo_middleware/healthcheck/__init__.py b/oslo_middleware/healthcheck/__init__.py
index 9e46bd8..cacc9b6 100644
--- a/oslo_middleware/healthcheck/__init__.py
+++ b/oslo_middleware/healthcheck/__init__.py
@@ -162,6 +162,23 @@ class Healthcheck(base.ConfigurableMiddleware):
 <H2>Result of {{results|length}} checks:</H2>
 <TABLE bgcolor="#ffffff" border="1">
 <TBODY>
+<TR>
+{% if detailed -%}
+<TH>
+Kind
+</TH>
+<TH>
+Reason
+</TH>
+<TH>
+Details
+</TH>
+{% else %}
+<TH>
+Reason
+</TH>
+{%- endif %}
+</TR>
 {% for result in results -%}
 {% if result.reason -%}
 <TR>
@@ -169,6 +186,9 @@ class Healthcheck(base.ConfigurableMiddleware):
     <TD>{{result.class|e}}</TD>
 {%- endif %}
     <TD>{{result.reason|e}}</TD>
+{% if detailed -%}
+    <TD>{{result.details|e}}</TD>
+{%- endif %}
 </TR>
 {%- endif %}
 {%- endfor %}
@@ -293,6 +313,7 @@ class Healthcheck(base.ConfigurableMiddleware):
             for result in results:
                 reasons.append({
                     'reason': result.reason,
+                    'details': result.details or '',
                     'class': reflection.get_class_name(result,
                                                        fully_qualified=False),
                 })
@@ -317,6 +338,7 @@ class Healthcheck(base.ConfigurableMiddleware):
         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),
diff --git a/oslo_middleware/healthcheck/disable_by_file.py b/oslo_middleware/healthcheck/disable_by_file.py
index cd438cf..a80a46e 100644
--- a/oslo_middleware/healthcheck/disable_by_file.py
+++ b/oslo_middleware/healthcheck/disable_by_file.py
@@ -44,11 +44,15 @@ class DisableByFileHealthcheck(pluginbase.HealthcheckBaseExtension):
         if path is None:
             LOG.warning(_LW('DisableByFile healthcheck middleware enabled '
                             'without disable_by_file_path set'))
-            return pluginbase.HealthcheckResult(available=True,
-                                                reason="OK")
+            return pluginbase.HealthcheckResult(
+                available=True, reason="OK",
+                details="No 'disable_by_file_path' configuration value"
+                        " specified")
         elif not os.path.exists(path):
-            return pluginbase.HealthcheckResult(available=True,
-                                                reason="OK")
+            return pluginbase.HealthcheckResult(
+                available=True, reason="OK",
+                details="Path '%s' was not found" % path)
         else:
-            return pluginbase.HealthcheckResult(available=False,
-                                                reason="DISABLED BY FILE")
+            return pluginbase.HealthcheckResult(
+                available=False, reason="DISABLED BY FILE",
+                details="Path '%s' was found" % path)
diff --git a/oslo_middleware/healthcheck/pluginbase.py b/oslo_middleware/healthcheck/pluginbase.py
index ffd3e08..92b2c09 100644
--- a/oslo_middleware/healthcheck/pluginbase.py
+++ b/oslo_middleware/healthcheck/pluginbase.py
@@ -14,12 +14,17 @@
 #    under the License.
 
 import abc
-import collections
 
 import six
 
-HealthcheckResult = collections.namedtuple(
-    'HealthcheckResult', ['available', 'reason'])
+
+class HealthcheckResult(object):
+    """Result of a ``healthcheck`` method call should be this object."""
+
+    def __init__(self, available, reason, details=None):
+        self.available = available
+        self.reason = reason
+        self.details = details
 
 
 @six.add_metaclass(abc.ABCMeta)