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https://github.com/mwarkentin/django-watchman

django-watchman exposes a status endpoint for your backing services like databases, caches, etc.
https://github.com/mwarkentin/django-watchman

cache database django django-watchman healthcheck monitoring panopta pingdom python

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django-watchman exposes a status endpoint for your backing services like databases, caches, etc.

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README 

        
=============================

django-watchman

=============================



.. image:: http://img.shields.io/pypi/v/django-watchman.svg

    :target: http://badge.fury.io/py/django-watchman



.. image:: http://img.shields.io/coveralls/mwarkentin/django-watchman.svg

    :target: https://coveralls.io/r/mwarkentin/django-watchman?branch=main



django-watchman exposes a status endpoint for your backing services like

databases, caches, etc.



.. image:: https://mwarkentin-snaps.s3.amazonaws.com/Watchmen_The_One_Thing_Nobody_Says_about_Adrian_Veidt_aka_Ozymandias_2022-03-23_08-36-18.png



Documentation

-------------



The full documentation is at http://django-watchman.rtfd.org.



Testimonials

------------



    We're in love with django-watchman. External monitoring is a vital part of our service offering. Using django-watchman we can introspect the infrastructure of an application via a secure URL. It's very well written and easy to extend. We've recommended it to many of our clients already.



— Hany Fahim, CEO, `VM Farms `_.



Quickstart

----------



1. Install ``django-watchman``::



    pip install django-watchman



2. Add ``watchman`` to your ``INSTALLED_APPS`` setting like this::



    INSTALLED_APPS = (

        ...

        'watchman',

    )



3. Include the watchman URLconf in your project ``urls.py`` like this::



    re_path(r'^watchman/', include('watchman.urls')),



4. Start the development server and visit ``http://127.0.0.1:8000/watchman/`` to

   get a JSON response of your backing service statuses::



    {

        "databases": [

            {

                "default": {

                    "ok": true

                }

            }

        ],

        "caches": [

            {

                "default": {

                    "ok": true

                }

            }

        ],

        "storage": {"ok": true}

    }



Pycon Canada Presentation (10 minutes)

--------------------------------------



.. image:: https://mwarkentin-snaps.s3.amazonaws.com/Full-stack_Django_application_monitoring_with_django-watchman_Michael_Warkentin_-_YouTube_2022-03-23_08-34-24.png

   :target: https://www.youtube.com/watch?v=iEgOCY7_zGI



Features

--------



Human-friendly dashboard

************************



Visit ``http://127.0.0.1:8000/watchman/dashboard/`` to get a human-friendly HTML

representation of all of your watchman checks.



Token based authentication

**************************



If you want to protect the status endpoint, you can use the ``WATCHMAN_TOKENS`` setting.

This is a comma-separated list of tokens.

When this setting is added, you must pass one of the tokens in as the ``watchman-token`` **GET** parameter::



    GET http://127.0.0.1:8000/watchman/?watchman-token=:token



Or by setting the ``Authorization: WATCHMAN-TOKEN`` header on the request::



    curl -X GET -H "Authorization: WATCHMAN-TOKEN Token=\":token\"" http://127.0.0.1:8000/watchman/



If you want to change the token name, you can set the ``WATCHMAN_TOKEN_NAME``.

The value of this setting will be the **GET** parameter that you must pass in::



    WATCHMAN_TOKEN_NAME = 'custom-token-name'



    GET http://127.0.0.1:8000/watchman/?custom-token-name=:token



**DEPRECATION WARNING**: ``WATCHMAN_TOKEN`` was replaced by the ``WATCHMAN_TOKENS`` setting to support multiple authentication tokens in django-watchman ``0.11``.

It will continue to work until it's removed in django-watchman ``1.0``.



Custom authentication/authorization

***********************************



If you want to protect the status endpoint with a customized

authentication/authorization decorator, you can add ``WATCHMAN_AUTH_DECORATOR``

to your settings. This needs to be a dotted-path to a decorator, and defaults

to ``watchman.decorators.token_required``::



    WATCHMAN_AUTH_DECORATOR = 'django.contrib.admin.views.decorators.staff_member_required'



Note that the ``token_required`` decorator does not protect a view unless

``WATCHMAN_TOKENS`` is set in settings.



Custom checks

*************



django-watchman allows you to customize the checks which are run by modifying

the ``WATCHMAN_CHECKS`` setting. In ``settings.py``::



    WATCHMAN_CHECKS = (

        'module.path.to.callable',

        'another.module.path.to.callable',

    )



You can also import the watchman.constants to include the DEFAULT_CHECKS and PAID_CHECKS in your ``settings.py``::



   from watchman import constants as watchman_constants



   WATCHMAN_CHECKS = watchman_constants.DEFAULT_CHECKS + ('module.path.to.callable', )



Checks take no arguments, and must return a ``dict`` whose keys are applied to the JSON response.



Use the ``watchman.decorators.check`` decorator to capture exceptions::



    from watchman.decorators import check



    def custom_check():

        return {"custom_check": _custom_check()}



    @check

    def _custom_check():

        return {"ok": True, "extra_info": "if helpful"}



In the absence of any checks, a 404 is thrown, which is then handled by the

``json_view`` decorator.



Run a subset of available checks

********************************



A subset of checks may be run, by passing ``?check=module.path.to.callable&check=...``

in the request URL. Only the callables given in the querystring which are also

in ``WATCHMAN_CHECKS`` should be run, eg::



    curl -XGET http://127.0.0.1:8080/watchman/?check=watchman.checks.caches



Skip specific checks

********************



You can skip any number of checks, by passing ``?skip=module.path.to.callable&skip=...``

in the request URL. Only the checks in ``WATCHMAN_CHECKS`` which are not in the

querystring should be run, eg::



    curl -XGET http://127.0.0.1:8080/watchman/?skip=watchman.checks.email



Check a subset of databases or caches

*************************************



If your application has a large number of databases or caches configured,

watchman may open too many connections as it checks each database or cache.



You can set the ``WATCHMAN_DATABASES`` or ``WATCHMAN_CACHES`` settings in order

to override the default set of databases and caches to be monitored.



Ping

****



If you want to simply check that your application is running and able to handle

requests, you can call ping:



    GET http://127.0.0.1:8000/watchman/ping/



It will return the text ``pong`` with a 200 status code. Calling this doesn't

run any of the checks.



Bare status view

****************



If you would like a "bare" status view (one that doesn't report any details,

just ``HTTP 200`` if checks pass, and ``HTTP 500`` if any checks fail), you

can use the ``bare_status`` view by putting the following into ``urls.py``::



    import watchman.views

    # ...

    re_path(r'^status/?$', watchman.views.bare_status),



Django management command

*************************



You can also run your checks without starting the webserver and making requests.

This can be useful for testing your configuration before enabling a server,

checking configuration on worker servers, etc. Run the management command like so::



    python manage.py watchman



By default, successful checks will not print any output. If all checks pass

successfully, the exit code will be ``0``. If a check fails, the exit code will

be ``1``, and the error message including stack trace will be printed to ``stderr``.



If you'd like to see output for successful checks as well, set verbosity to

``2`` or higher::



    python manage.py watchman -v 2

    {"storage": {"ok": true}}

    {"caches": [{"default": {"ok": true}}]}

    {"databases": [{"default": {"ok": true}}]}



If you'd like to run a subset of checks, use ``-c`` and a comma-separated list

of python module paths::



    python manage.py watchman -c watchman.checks.caches,watchman.checks.databases -v 2

    {"caches": [{"default": {"ok": true}}]}

    {"databases": [{"default": {"ok": true}}]}



If you'd like to skip certain checks, use ``-s`` and a comma-separated list of

python module paths::



    python manage.py watchman -s watchman.checks.caches,watchman.checks.databases -v 2

    {"storage": {"ok": true}}



Use ``-h`` to see a full list of options::



    python manage.py watchman -h



X-Watchman-Version response header

**********************************



Watchman can return the version of watchman which is running to help you keep

track of whether or not your sites are using an up-to-date version. This is

disabled by default to prevent any unintended information leakage for websites

without authentication. To enable, update the ``EXPOSE_WATCHMAN_VERSION``

setting::



    EXPOSE_WATCHMAN_VERSION = True



Custom response code

********************



By default, watchman will return a ``500`` HTTP response code, even if there's a

failing check. You can specify a different response code for failing checks

using the ``WATCHMAN_ERROR_CODE`` setting::



    WATCHMAN_ERROR_CODE = 200



Logging

*******



watchman includes log messages using a logger called ``watchman``.

You can configure this by configuring the ``LOGGING`` section of your Django

settings file.



Here is a simple example that would log to the console::



    LOGGING = {

        'version': 1,

        'disable_existing_loggers': False,

        'handlers': {

            'console': {

                'class': 'logging.StreamHandler',

            },

        },

        'loggers': {

            'watchman': {

                'handlers': ['console'],

                'level': 'DEBUG',

            },

        },

    }



More information is available in the `Django documentation

`_.



APM (Datadog, New Relic)

************************



If you're using APM and watchman is being often hit for health checks (such as an ELB on

AWS), you will find some stats based on averages will be affected (average transaction

time, apdex, etc):



You can disable APM instrumentation for watchman by using the ``WATCHMAN_DISABLE_APM``

setting::



    WATCHMAN_DISABLE_APM = True



This currently supports the following agents:



* Datadog

* New Relic



Please open an issue if there's another APM you use which is being affected.



Available checks

----------------



caches

******



For each cache in ``django.conf.settings.CACHES``:



* Set a test cache item

* Get test item

* Delete test item



databases

*********



For each database in ``django.conf.settings.DATABASES``:



* Verify connection by calling ``connections[database].introspection.table_names()``



email

*****



Send a test email to ``[email protected]`` using ``django.core.mail.send_mail``.



If you're using a 3rd party mail provider, this check could end up costing you

money, depending how aggressive you are with your monitoring. For this reason,

this check is **not enabled** by default.



For reference, if you were using Mandrill, and hitting your watchman endpoint

once per minute, this would cost you ~$5.60/month.



**Custom Settings**



* ``WATCHMAN_EMAIL_SENDER`` (default: ``[email protected]``): Specify an email to be the sender of the test email

* ``WATCHMAN_EMAIL_RECIPIENTS`` (default: ``[[email protected]]``): Specify a list of email addresses to send the test email

* ``WATCHMAN_EMAIL_HEADERS`` (default: ``{}``): Specify a dict of custom headers to be added to the test email



storage

*******



Using ``django.core.files.storage.default_storage``:



* Write a test file

* Check the test file's size

* Read the test file's contents

* Delete the test file



By default the test file gets written on the root of the django ``MEDIA_ROOT``.



There are two reasons why you may need to override this.  You can use

the setting ``WATCHMAN_STORAGE_PATH`` to accomplish this.



1) Django triggers a `django.core.exceptions.SuspiciousFileOperation

`

on the storage check.



2) If for whatever reason, the base of ``MEDIA_ROOT`` is not writable by

the user that runs Django.



In either case, choose a path within and relative to ``MEDIA_ROOT``.



  WATCHMAN_STORAGE_PATH = "django-watchman/"



If the ``MEDIA_ROOT`` is already defined::



  from os.path import join as joinpath

  WATCHMAN_STORAGE_PATH = joinpath(MEDIA_ROOT, "django-watchman/")



Default checks

**************



By default, django-watchman will run checks against your databases

(``watchman.checks.databases``), caches (``watchman.checks.caches``), and

storage (``watchman.checks.storage``).



Paid checks

***********



Paid checks are checks which may cost you money if they are run regularly.



Currently there is only one "paid" check - ``watchman.checks.email``. Many

times email is sent using managed services like SendGrid or Mailgun. You can

enable it by setting the ``WATCHMAN_ENABLE_PAID_CHECKS`` to ``True``, or by

overriding the ``WATCHMAN_CHECKS`` setting.



Trying it out with Docker

--------------------------



A sample project is available along with a Dockerfile to make it easy to try

out django-watchman. It includes examples of how to write simple custom checks.



One of the custom checks will always fail, so if you want to see what responses

look like with 100% succeeding checks, add `?skip=sample_project.checks.fail_custom_check`



Requirements

************



* `Docker `



Instructions

************



1. Build and run the Docker image with the current local code: ``make run``

2. Visit watchman json endpoint in your browser: http://127.0.0.1:8000/watchman/

3. Visit watchman json endpoint in your browser: http://127.0.0.1:8000/watchman/?skip=sample_project.checks.fail_custom_check

4. Visit watchman dashboard in your browser: http://127.0.0.1:8000/watchman/dashboard/

5. Visit watchman dashboard in your browser: http://127.0.0.1:8000/watchman/dashboard/?skip=sample_project.checks.fail_custom_check

6. Visit watchman ping in your browser: http://127.0.0.1:8000/watchman/ping/

7. Visit watchman bare status in your browser: http://127.0.0.1:8000/watchman/bare/