Improvements to health checks

- Adds a warning endpoint for warning-only checks
- Changes the default for the disk space check to 1%, instead of 10%
- Removes instance services from the overall health check endpoint

health/healthcheck.py

@@ -3,7 +3,7 @@ import logging
 
 from auth.permissions import SuperUserPermission
 from flask import session
-from health.services import check_all_services
+from health.services import check_all_services, check_warning_services
 
 logger = logging.getLogger(__name__)
 
@@ -20,12 +20,20 @@ class HealthCheck(object):
     self.instance_keys = instance_keys
     self.instance_skips = instance_skips or []
 
+  def check_warning(self):
+    """
+    Conducts a check on the warnings, returning a dict representing the HealthCheck
+    output and a number indicating the health check response code.
+    """
+    service_statuses = check_warning_services(self.app, [])
+    return self.get_instance_health(service_statuses)
+
   def check_instance(self):
     """
     Conducts a check on this specific instance, returning a dict representing the HealthCheck
     output and a number indicating the health check response code.
     """
-    service_statuses = check_all_services(self.app, self.instance_skips)
+    service_statuses = check_all_services(self.app, self.instance_skips, for_instance=True)
     return self.get_instance_health(service_statuses)
 
   def check_endtoend(self):
@@ -33,7 +41,7 @@ class HealthCheck(object):
     Conducts a check on all services, returning a dict representing the HealthCheck
     output and a number indicating the health check response code.
     """
-    service_statuses = check_all_services(self.app, [])
+    service_statuses = check_all_services(self.app, [], for_instance=False)
     return self.calculate_overall_health(service_statuses)
 
   def get_instance_health(self, service_statuses):

health/services.py

@@ -94,50 +94,77 @@ def _disk_within_threshold(path, threshold):
   return (1.0 - (usage.percent / 100.0)) >= threshold
 
 
-def _check_disk_space(app):
-  """ Returns the status of the disk space for this instance. If the available disk space is below
-      a certain threshold, then will return False.
-  """
-  if not app.config.get('SETUP_COMPLETE', False):
-    return (True, 'Stack not fully setup; skipping check')
+def _check_disk_space(for_warning):
+  def _check_disk_space(app):
+    """ Returns the status of the disk space for this instance. If the available disk space is below
+        a certain threshold, then will return False.
+    """
+    if not app.config.get('SETUP_COMPLETE', False):
+      return (True, 'Stack not fully setup; skipping check')
 
-  # Check the directory in which we're running.
-  currentfile = os.path.abspath(__file__)
-  if not _disk_within_threshold(currentfile, app.config.get('DISKSPACE_HEALTH_THRESHOLD', 0.1)):
-    stats = psutil.disk_usage(currentfile)
-    logger.debug('Disk space on main volume: %s', stats)
-    return (False, 'Disk space has gone below threshold on main volume: %s' % stats.percent)
+    config_key = ('DISKSPACE_HEALTH_WARNING_THRESHOLD'
+                  if for_warning else 'DISKSPACE_HEALTH_THRESHOLD')
+    default_threshold = 0.1 if for_warning else 0.01
 
-  # Check the temp directory as well.
-  tempdir = tempfile.gettempdir()
-  if tempdir is not None:
-    if not _disk_within_threshold(tempdir, app.config.get('DISKSPACE_HEALTH_THRESHOLD', 0.1)):
-      stats = psutil.disk_usage(tempdir)
-      logger.debug('Disk space on temp volume: %s', stats)
-      return (False, 'Disk space has gone below threshold on temp volume: %s' % stats.percent)
+    # Check the directory in which we're running.
+    currentfile = os.path.abspath(__file__)
+    if not _disk_within_threshold(currentfile, app.config.get(config_key, default_threshold)):
+      stats = psutil.disk_usage(currentfile)
+      logger.debug('Disk space on main volume: %s', stats)
+      return (False, 'Disk space has gone below threshold on main volume: %s' % stats.percent)
 
-  return (True, '')
+    # Check the temp directory as well.
+    tempdir = tempfile.gettempdir()
+    if tempdir is not None:
+      if not _disk_within_threshold(tempdir, app.config.get(config_key, default_threshold)):
+        stats = psutil.disk_usage(tempdir)
+        logger.debug('Disk space on temp volume: %s', stats)
+        return (False, 'Disk space has gone below threshold on temp volume: %s' % stats.percent)
+
+    return (True, '')
+
+  return _check_disk_space
 
 
-_SERVICES = {
+_INSTANCE_SERVICES = {
   'registry_gunicorn': _check_gunicorn('v1/_internal_ping'),
   'web_gunicorn': _check_gunicorn('_internal_ping'),
   'verbs_gunicorn': _check_gunicorn('c1/_internal_ping'),
+  'service_key': _check_service_key,
+  'disk_space': _check_disk_space(for_warning=False),
+}
+
+_GLOBAL_SERVICES = {
   'database': _check_database,
   'redis': _check_redis,
   'storage': _check_storage,
   'auth': _check_auth,
-  'service_key': _check_service_key,
-  'disk_space': _check_disk_space,
 }
 
-def check_all_services(app, skip):
+_WARNING_SERVICES = {
+  'disk_space_warning': _check_disk_space(for_warning=True),
+}
+
+def check_all_services(app, skip, for_instance=False):
   """ Returns a dictionary containing the status of all the services defined. """
+  if for_instance:
+    services = dict(_INSTANCE_SERVICES)
+    services.update(_GLOBAL_SERVICES)
+  else:
+    services = _GLOBAL_SERVICES
+
+  return _check_services(app, skip, services)
+
+def check_warning_services(app, skip):
+  """ Returns a dictionary containing the status of all the warning services defined. """
+  return _check_services(app, skip, _WARNING_SERVICES)
+
+def _check_services(app, skip, services):
   status = {}
-  for name in _SERVICES:
+  for name in services:
     if name in skip:
       continue
 
-    status[name] = _SERVICES[name](app)
+    status[name] = services[name](app)
 
   return status