Add support for warnings that do not error endpoints

Add a new concept of warnings and non-critical services. Both
will not cause the template and JSON endpoint to response with a
500 status code but with a regular 200. This change is backwards
compatible because the existing warnings are treated as errors by
default.

Close #191

.editorconfig

@@ -17,8 +17,9 @@ multi_line_output = 5
 line_length = 80
 combine_as_imports = true
 skip = wsgi.py,docs,.tox,env,.eggs
-known_first_party = health_check,health_check_cache,health_check_celery,health_check_celery3,health_check_db,health_check_storage,tests
-known_third_party = django
+known_first_party = health_check,tests
+known_third_party = django,celery,psutil
+default_section=THIRDPARTY
 not_skip = __init__.py
 
 

.gitignore

@@ -1,15 +1,104 @@
-/.idea/
-*.pyc
-*.db
-/project/
-/dist
-*.egg-info
-.DS_Store
-/build
-*#
-*~
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+env/
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
 .tox/
-.cache/
 .coverage
-.eggs
-/docs/_build
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# dotenv
+.env
+
+# virtualenv
+.venv
+venv/
+ENV/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+
+# pytest
+.pytest_cache/

README.rst

@@ -165,6 +165,10 @@ Writing a health check is quick and easy:
     from health_check.backends import BaseHealthCheckBackend
 
     class MyHealthCheckBackend(BaseHealthCheckBackend):
+        #: The status endpoints will respond with a 200 status code
+        #: even if the check errors.
+        critical_service = False
+
         def check_status(self):
             # The test code goes here.
             # You can use `self.add_error` or

docs/settings.rst

@@ -3,6 +3,13 @@ Settings
 
 Settings can be configured via the ``HEALTH_CHECK`` dictionary.
 
+.. data:: WARNINGS_AS_ERRORS
+
+    Treats :class:`ServiceWarning` as errors, meaning they will case the views
+    to respond with a 500 status code. Default is ``True``. If set to
+    ``False`` warnings will be displayed in the template on in the JSON
+    response but the status code will remain a 200.
+
 Security
 --------
 

health_check/backends.py

@@ -9,6 +9,14 @@
 
 
 class BaseHealthCheckBackend:
+    critical_service = True
+    """
+    Define if service is critical to the operation of the site.
+
+    If set to ``False`` service failures will cause a 500 response code on the
+    health check endpoint.
+    """
+
     def __init__(self):
         self.errors = []
 

health_check/conf.py

@@ -0,0 +1,6 @@
+from django.conf import settings
+
+HEALTH_CHECK = getattr(settings, 'HEALTH_CHECK', {})
+HEALTH_CHECK.setdefault('DISK_USAGE_MAX', 90)
+HEALTH_CHECK.setdefault('MEMORY_MIN', 100)
+HEALTH_CHECK.setdefault('WARNINGS_AS_ERRORS', True)

health_check/contrib/psutil/backends.py

@@ -1,22 +1,18 @@
 import locale
 import socket
 
-from django.conf import settings
-
 import psutil
+
 from health_check.backends import BaseHealthCheckBackend
+from health_check.conf import HEALTH_CHECK
 from health_check.exceptions import (
     ServiceReturnedUnexpectedResult, ServiceWarning
 )
 
 host = socket.gethostname()
 
-if hasattr(settings, 'HEALTH_CHECK'):
-    DISK_USAGE_MAX = settings.HEALTH_CHECK.get('DISK_USAGE_MAX', 90)  # in %
-    MEMORY_MIN = settings.HEALTH_CHECK.get('MEMORY_MIN', 100)  # in MB
-else:
-    DISK_USAGE_MAX = 90  # in %
-    MEMORY_MIN = 100  # in MB
+DISK_USAGE_MAX = HEALTH_CHECK['DISK_USAGE_MAX']
+MEMORY_MIN = HEALTH_CHECK['MEMORY_MIN']
 
 
 class DiskUsage(BaseHealthCheckBackend):

health_check/exceptions.py

@@ -12,6 +12,13 @@ def __str__(self):
 
 
 class ServiceWarning(HealthCheckException):
+    """
+    Warning of service misbehavior.
+
+    If the ``HEALTH_CHECK['WARNINGS_AS_ERRORS']`` is set to ``False``,
+    these exceptions will not case a 500 status response.
+    """
+
     message_type = _("warning")
 
 

health_check/views.py

@@ -1,12 +1,16 @@
 import copy
 from concurrent.futures import ThreadPoolExecutor
 
+from django.conf import settings
 from django.http import JsonResponse
 from django.views.decorators.cache import never_cache
 from django.views.generic import TemplateView
 
+from health_check.exceptions import ServiceWarning
 from health_check.plugins import plugin_dir
 
+WARNINGS_AS_ERRORS = getattr(settings, 'HEALTH_CHECK_WARNINGS_AS_ERRORS', True)
+
 
 class MainView(TemplateView):
     template_name = 'health_check/index.html'
@@ -23,14 +27,20 @@ def get(self, request, *args, **kwargs):
         def _run(plugin):
             plugin.run_check()
             try:
-                return plugin.errors
+                return plugin.errors, plugin
             finally:
                 from django.db import connection
                 connection.close()
 
         with ThreadPoolExecutor(max_workers=len(plugins) or 1) as executor:
-            for ers in executor.map(_run, plugins):
-                errors.extend(ers)
+            for plugin_errors, plugin in executor.map(_run, plugins):
+                if plugin.critical_service:
+                    if not WARNINGS_AS_ERRORS:
+                        plugin_errors = (
+                            e for e in plugin_errors
+                            if not isinstance(e, ServiceWarning)
+                        )
+                    errors.extend(plugin_errors)
 
         status_code = 500 if errors else 200
 

setup.cfg

@@ -26,6 +26,10 @@ keywords =
 packages =
   health_check
 
+[pbr]
+skip_authors = true
+skip_changelog = true
+
 [tool:pytest]
 norecursedirs=venv env .eggs
 DJANGO_SETTINGS_MODULE=tests.testapp.settings