django-watchman 1.3.0

django-watchman exposes a status endpoint for your backing services

django-watchman

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

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)

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

@check
def my_check():
    return {'x': 1}

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 [e-mail] 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: [e-mail]): Specify an email to be the sender of the test email

• WATCHMAN_EMAIL_RECIPIENTS (default: [[e-mail]]): 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. If for whatever reasons this path is not writable by the user that runs the application you can override it by setting WATCHMAN_STORAGE_PATH to a specific path. Remember that this must be within the MEDIA_ROOT, which by default is your project root. In settings.py:

WATCHMAN_STORAGE_PATH = "/path_to_your_app/foo/bar/"

If the MEDIA_ROOT is already defined:

from os.path import join as joinpath
WATCHMAN_STORAGE_PATH = joinpath(MEDIA_ROOT, "foo/bar")

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

Currently there is only one “paid” check - watchman.checks.email. 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.

Requirements

• Docker <https://www.docker.com/get-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 dashboard in your browser: http://127.0.0.1:8000/watchman/dashboard/

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

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

History

Unreleased

1.3.0 (2022-02-24)

• [#181] Update sample project to Django 4.x

• [#171] Improve database check performance: replace introspection.table_names() by a simple cursor query (@cristianemoyano)

• [#180, #174,] Switch testing to Github Actions from TravisCI, update to latest versions

• [#178] Add black, flake8, and isort linting

1.2.0 (2020-09-20)

• [#163] Replaced deprecated url() calls with re_path() (@dominik-bln)

1.1.1 (2020-05-04)

• [#159] Fixed invalid escape sequence in decorators by changing to a raw string

1.1.0 (2020-03-16)

• [#154] Added custom path support for storage check

1.0.1 (YYYY-MM-DD)

• Fix modal popups on dashboards when Type or Name fields contains spaces (@maikeps)

1.0.0 (2019-12-18)

• Official django-watchman 1.0 release! Releases will (try to) follow semantic versioning from now on.

• Drop support for python 2 and Django<2 (@JBKahn)

• Drop usage of django-jsonview in favor of the Django’s built in JsonResponse (@JBKahn)

0.18.0 (2019-08-19)

• [#142] Skip traces in Datadog if WATCHMAN_DISABLE_APM is enabled (@robatwave)

0.17.0 (2019-06-14)

• [#141] Disable APM monitoring on ping endpoint if settings.WATCHMAN_DISABLE_APM is configured (@JBKahn)

0.16.0 (2019-03-19)

• [#131] Make watchman constants importable (@jonespm)

• [#134] Update Django/Python versions & clean up sample site Docker (@JayH5)

0.15.0 (2018-02-27)

• [#114] Add “bare” status view (@jamesmallen)

• [#115] Adds WATCHMAN_DISABLE_APM option (@xfxf)

• [#63] Disable watchman version output by default, add EXPOSE_WATCHMAN_VERSION setting (@mwarkentin)

0.14.0 (2018-01-09)

• [#110] Replace vagrant + ansible with Dockerfile (@ryanwilsonperkin)

• [#111] Configure Django logging for checks (@dhoffman34)

• [#112] Add simple HTTP ping endpoint (@dhoffman34)

0.13.1 (2017-05-27)

• [#101] Write bytes to dummy file on storage check to fix an issue in Python 3 (thanks @saily!)

0.13.0 (2017-05-23)

• [#105] Add WATCHMAN_CACHES and WATCHMAN_DATABASES settings to override the Django defaults

  • When using watchman with a large number of databases, the default checks can cause an excess of connections to the database / cache

  • New settings allow you to check only a subset of databases / caches

  • Watchman will still default to checking all databases / caches, so no changes necessary for most apps

0.12.0 (2017-02-22)

• [#100] Add WATCHMAN_EMAIL_SENDER setting to customize email check “from” address

0.11.1 (2017-02-14)

• [#99] Fix verbose output in management command on Django 1.8+

0.11.0 (2016-08-02)

• Update tests to run on Django 1.7 - 1.10

• [#87] Fix 500 errors with ATOMIC_REQUESTS enabled

  • Disables atomic transactions on the watchman views to prevent generic 500 errors

• [#88] Restructure dashboard and switch icon libraries

  • Make check types singular on dashboard

  • Switch to FontAwesome instead of Glyphicon to track Bootstrap updates

  • Improve traceback display width

• [#92] Support multiple auth tokens

  • Fixes [#86]

  • Deprecates settings.WATCHMAN_TOKEN and adds settings.WATCHMAN_TOKENS

0.10.1 (2016-05-03)

• [#81] Fix header-based authentication for tokens w/ dashes (-)

  • Regex was overly specific for header values (w)

  • Added TODO to follow up with a full regex for valid characters according to the spec

0.10.0 (2016-05-02)

• [#75] Enable header-based authentication

  • Set a header instead of passing the token via GET param: "Authorization: WATCHMAN-TOKEN Token=\":token\""

  • Improves security by keeping tokens out of logs

• [#79] Enable customization of email check

  • Add WATCHMAN_EMAIL_RECIPIENTS setting - pass a list of recipients the email should be sent to

  • Add WATCHMAN_EMAIL_HEADERS setting - pass a dict of custom headers to be set on the email

0.9.0 (2015-12-16)

• [#51] Update TravisCI Python / Django versions

• [#52] Fix deprecated url_patterns

• [#53] Change default error response code to 500

• [#56] Add @check decorator and refactor existing checks to use it (thanks @benwebber!)

• [#57] Sort caches / databases in response for more consistent responses

• [#59] Add .editorconfig for improved consistency in contributions

• [#61] Add Vagrantfile and docs for how to run and develop on Vagrant instance

• [#65] Include assets in source tarball for Debian packaging (thanks @fladi)

• [#71] Unpin django-jsonview in setup.py

• [#72] Fix stacktrace on dashboard modal and increase width for better readability

0.8.0 (2015-10-03)

• [#46] Allow custom response codes with the WATCHMAN_ERROR_CODE setting

0.7.1 (2015-08-14)

• Update headers in HISTORY.rst to attempt to fix localshop parsing issues

0.7.0 (2015-08-14)

• [#40] Bump django-jsonview for improved Django 1.8 compatibility

  • Also brought travis Django test versions in line with currently supported Django versions (1.4.x, 1.7.x, 1.8.x)

0.6.0 (2015-07-02)

• [#30] Allow users to specify a custom authentication/authorization decorator

  • Override the @auth decorator by setting WATCHMAN_AUTH_DECORATOR to a dot-separated path to your own decorator

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

  • Token-based authentication remains the default

• [#31], [#34] Add a human-friendly status dashboard

  • Available at <watchman url>/dashboard/

  • ?check & ?skip GET params work on the dashboard as well

• [#35] Add X-Watchman-Version header to responses

0.5.0 (2015-01-25)

• Add watchman management command

  • Exit code of 0 if all checks pass, 1 otherwise

  • Print json stacktrace to stderr if check fails

  • Handles --verbosity option to print all status checks

  • -c, --checks, -s, --skips options take comma-separated list of python paths to run / skip

• Improve identifiability of emails sent from a django-watchman endpoint

  • From: [e-mail]

  • Subject: django-watchman email check

  • Body: This is an automated test of the email system.

  • Add X-DJANGO-WATCHMAN: True custom header

• Add new default check: storage check

  • Checks that files can be both written and read with the current Django storage engine

  • Add WATCHMAN_ENABLE_PAID_CHECKS setting to enable all paid checks without modifying WATCHMAN_CHECKS

• Remove email_status from default checks

• Refactor utils.get_checks to allow reuse in management command

  • get_checks now performs the optional check inclusion / skipping

  • status refactored to pull check_list / skip_list from GET params and pass them to get_checks

• Namespace cache keys

• Update documentation

0.4.0 (2014-09-08)

• Add the ability to skip certain checks by passing one or more skip=path.to.callable GET params when hitting the watchman URL

0.3.0 (2014-09-05)

• New check - email (watchman.checks.email_status)! django-watchman will now check that your email settings are working too!

• Fix a few small issues in the readme

• Rearrange some of the code in checks.py

0.2.2 (2014-09-05)

• Fix and run tests on Python 2.7 and 3.4

• Bump django-jsonview dependency to latest

• Update tox envlist and travis config to test 2.7 / 3.4

0.2.1 (2014-09-04)

• Initialize django during tests to prevent app loading issue for Django >= 1.7

• Suppress MIDDLEWARE_CLASSES warning for Django >= 1.7

• Reorganize test imports

• Fix make test, make coverage, make release commands

• Add htmlcov/ directory to .gitignore

• Test django 1.4, 1.6, 1.7

0.2.0 (2014-09-04)

• Custom checks can now be written and run using the WATCHMAN_CHECKS setting

• A subset of the available checks can be run by passing the check GET param when hitting the watchman url

0.1.2 (2014-02-21)

• Move package requirements out of requirements.txt and into setup.py

0.1.1 (2014-02-09)

• Remove django>=1.5.5 version specification

• Remove wheel requirement

0.1.0 (2014-02-08)

• First release on PyPI.