Run checks on services like databases, queue servers, celery processes, etc.
Project description
This project checks for various conditions and provides reports when anomalous behavior is detected.
The following health checks are bundled with this project:
cache
database
storage
disk and memory utilization (via psutil)
AWS S3 storage
Celery task queue
Writing your own custom health checks is also very quick and easy.
We also like contributions, so don’t be afraid to make a pull request.
Use Cases
The primary intended use case is to monitor conditions via HTTP(S), with responses available in HTML and JSON formats. When you get back a response that includes one or more problems, you can then decide the appropriate course of action, which could include generating notifications and/or automating the replacement of a failing node with a new one. If you are monitoring health in a high-availability environment with a load balancer that returns responses from multiple nodes, please note that certain checks (e.g., disk and memory usage) will return responses specific to the node selected by the load balancer.
Supported Versions
We officially only support the latest version of Python as well as the latest version of Django and the latest Django LTS version.
Installation
First install the django-health-check package:
pip install django-health-checkAdd the health checker to a URL you want to use:
urlpatterns = [
# ...
url(r'^ht/', include('health_check.urls')),
]Add the health_check applications to your INSTALLED_APPS:
INSTALLED_APPS = [
# ...
'health_check', # required
'health_check.db', # stock Django health checkers
'health_check.cache',
'health_check.storage',
'health_check.contrib.celery', # requires celery
'health_check.contrib.psutil', # disk and memory utilization; requires psutil
'health_check.contrib.s3boto_storage', # requires boto and S3BotoStorage backend
](Optional) If using the psutil app, you can configure disk and memory threshold settings; otherwise below defaults are assumed. If you want to disable one of these checks, set its value to None.
HEALTH_CHECK = {
'DISK_USAGE_MAX': 90, # percent
'MEMORY_MIN' = 100, # in MB
}If using the DB check, run migrations:
django-admin migrateSetting up monitoring
You can use tools like Pingdom or other uptime robots to monitor service status. The /ht/ endpoint will respond a HTTP 200 if all checks passed and a HTTP 500 if any of the tests failed.
$ curl -v -X GET -H http://www.example.com/ht/
> GET /ht/ HTTP/1.1
> Host: www.example.com
> Accept: */*
>
< HTTP/1.1 200 OK
< Content-Type: text/html; charset=utf-8
<!-- This is an excerpt -->
<div class="container">
<h1>System status</h1>
<table>
<tr>
<td class="status_1"></td>
<td>CacheBackend</td>
<td>working</td>
</tr>
<tr>
<td class="status_1"></td>
<td>DatabaseBackend</td>
<td>working</td>
</tr>
<tr>
<td class="status_1"></td>
<td>S3BotoStorageHealthCheck</td>
<td>working</td>
</tr>
</table>
</div>Getting machine readable JSON reports
If you want machine readable status reports you can request the /ht/ endpoint with the Accept HTTP header set to application/json.
The backend will return a JSON response:
$ curl -v -X GET -H "Accept: application/json" http://www.example.com/ht/
> GET /ht/ HTTP/1.1
> Host: www.example.com
> Accept: application/json
>
< HTTP/1.1 200 OK
< Content-Type: application/json
{
"CacheBackend": "working",
"DatabaseBackend": "working",
"S3BotoStorageHealthCheck": "working"
}Writing a custom health check
Writing a health check is quick and easy:
from health_check.backends import BaseHealthCheckBackend
class MyHealthCheckBackend(BaseHealthCheckBackend):
def check_status(self):
# The test code goes here.
# You can use `self.add_error` or
# raise a `HealthCheckException`,
# similar to Django's form validation.
pass
def identifier(self):
return self.__class__.__name__ # Display name on the endpoint.After writing a custom checker, register it in your app configuration:
from django.apps import AppConfig
from health_check.plugins import plugin_dir
class MyAppConfig(AppConfig):
name = 'my_app'
def ready(self):
from .backends import MyHealthCheckBackend
plugin_dir.register(MyHealthCheckBackend)Make sure the application you write the checker into is registered in your INSTALLED_APPS.
Customizing output
You can customize HTML or JSON rendering by inheriting from MainView in health_check.views and customizing the template_name, get, render_to_response and render_to_response_json properties:
# views.py
from health_check.views import MainView
class HealthCheckCustomView(MainView):
template_name = 'myapp/health_check_dashboard.html' # customize the used templates
def get(self, request, *args, **kwargs):
plugins = []
# ...
if 'application/json' in request.META.get('HTTP_ACCEPT', ''):
return self.render_to_response_json(plugins, status)
return self.render_to_response(plugins, status)
def render_to_response(self, plugins, status): # customize HTML output
return HttpResponse('COOL' if status == 200 else 'SWEATY', status=status)
def render_to_response_json(self, plugins, status): # customize JSON output
return JsonResponse(
{str(p.identifier()): 'COOL' if status == 200 else 'SWEATY' for p in plugins}
status=status
)
# urls.py
import views
urlpatterns = [
# ...
url(r'^ht/$', views.HealthCheckCustomView.as_view(), name='health_check_custom'),
]Other resources
django-watchman is a package that does some of the same things in a slightly different way.
See this weblog about configuring Django and health checking with AWS Elastic Load Balancer.
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