thomastu / django-alive

Healthchecks for Django

django-alive 🕺

Provides two healthcheck endpoints for your Django application:

Alive

Verifies the WSGI server is responding.

• Default URL: /-/alive/
• Success:
  • status code: 200
  • content: ok
• Failure: This view never returns a failure. A failure would mean your WSGI server is not running.

Health

Verifies services are ready.

• Default URL: /-/health/
• Success:
  • status_code: 200
  • content: {"healthy": true}
• Failure:
  • status_code: 503
  • content: {"healthy": false, "errors": ["error 1", "error 2"]}

By default the health endpoint will test the database connection, but can be configured to check the cache, staticfiles, or any additional custom checks.

Supports Django 1.10+ on both Python 2 & 3.

Install

pip install django-alive

Configure

Add this to your project's urlpatterns:

path("-/", include("django_alive.urls"))

For versions before Django 2.0, use:

url(r"-/", include("django_alive.urls"))

Enabling Checks

The default "health" endpoint will test a simple SELECT 1 query on the database. Additional checks can be enabled in your Django settings.

Use the ALIVE_CHECKS setting to configure the checks to include. It is a dictionary with the path to a Python function as a key and any keyword arguments to pass to that function as a value. A full example:

ALIVE_CHECKS = {
    "django_alive.checks.check_database": {},
    "django_alive.checks.check_staticfile": {
        "filename": "img/favicon.ico",
    },
    "django_alive.checks.check_cache": {
        "cache": "session",
        "key": "test123",
    },
}

Custom Checks

django-alive is designed to easily extend with your own custom checks. Simply define a function which performs your check and raises a django_alive.HealthcheckFailure exception in the event of a failure. See checks.py for some examples on how to write a check.

Disabling ALLOWED_HOSTS for Healthchecks

Often, load balancers will not pass a Host header when probing a healthcheck endpoint. This presents a problem for Django's host header validation. A middleware is included that will turn off the host checking only for the healthcheck endpoints. This is safe since these views never do anything with the Host header.

Enable the middleware by inserting this at the beginning of your MIDDLEWARE:

MIDDLEWARE = [
    "django_alive.middleware.healthcheck_bypass_host_check",
    # ...
]

Handling SECURE_SSL_REDIRECT

If your load balancer is doing HTTPS termination and you have SECURE_SSL_REDIRECT=True in your settings, you want to make sure that your healtcheck URLs are not also redirected to HTTPS. In that case, add the following to your settings:

SECURE_REDIRECT_EXEMPT = [r"^-/"]  # django-alive URLs