healthchecks

healthchecks is a watchdog for your cron jobs. It's a web server that listens for pings from your cron jobs, plus a web interface.

It is live here: http://healthchecks.io/

The building blocks are:

• Python 2 or Python 3
• Django 1.9
• PostgreSQL or MySQL

Setting Up for Development

These are instructions for setting up HealthChecks Django app in development environment.

• prepare directory for project code and virtualenv:

    $ mkdir -p ~/webapps
    $ cd ~/webapps
  

• prepare virtual environment (with virtualenv you get pip, we'll use it soon to install requirements):

    $ virtualenv --python=python3 hc-venv
    $ source hc-venv/bin/activate
  

• check out project code:

    $ git clone https://github.com/andela/-Healthchecks_Mugiwara.git
  

• install requirements (Django, ...) into virtualenv:

    $ pip install -r healthchecks/requirements.txt
  

• make sure PostgreSQL server is installed and running, create database "hc":

    $ psql --user postgres
    postgres=# create database hc;
  

• create database tables, triggers, superuser:

    $ cd ~/webapps/healthchecks
    $ ./manage.py migrate
    $ ./manage.py ensuretriggers
    $ ./manage.py createsuperuser
  

• run development server:

    $ ./manage.py runserver
  

The site should now be running at http://localhost:8080 To log into Django administration site as a super user, visit http://localhost:8080/admin

Database Configuration

Database configuration is stored in hc/settings.py and can be overriden in hc/local_settings.py. The default database engine is SQLite. To use PostgreSQL, create hc/local_settings.py if it does not exist, and put the following in it, changing it as neccessary:

DATABASES = {
    'default': {
        'ENGINE':   'django.db.backends.postgresql',
        'NAME':     'your-database-name-here',
        'USER':     'your-database-user-here',
        'PASSWORD': 'your-database-password-here',
        'TEST': {'CHARSET': 'UTF8'}
    }
}

For MySQL:

DATABASES = {
    'default': {
        'ENGINE':   'django.db.backends.mysql',
        'NAME':     'your-database-name-here',
        'USER':     'your-database-user-here',
        'PASSWORD': 'your-database-password-here',
        'TEST': {'CHARSET': 'UTF8'}
    }
}

You can also use hc/local_settings.py to read database configuration from environment variables like so:

import os

DATABASES = {
    'default': {
        'ENGINE':   os.env['DB_ENGINE'],
        'NAME':     os.env['DB_NAME'],
        'USER':     os.env['DB_USER'],
        'PASSWORD': os.env['DB_PASSWORD'],
        'TEST': {'CHARSET': 'UTF8'}
    }
}

Sending Emails

healthchecks must be able to send email messages, so it can send out login links and alerts to users. You will likely need to tweak email configuration before emails will work. healthchecks uses djmail for sending emails asynchronously. Djmail is a BSD Licensed, simple and nonobstructive django email middleware. It can be configured to use any regular Django email backend behind the scenes. For example, the healthchecks.io site uses django-ses-backend and the email configuration in hc/local_settings.py looks as follows:

DJMAIL_REAL_BACKEND = 'django_ses_backend.SESBackend'
AWS_SES_ACCESS_KEY_ID = "put-access-key-here"
AWS_SES_SECRET_ACCESS_KEY = "put-secret-access-key-here"
AWS_SES_REGION_NAME = 'us-east-1'
AWS_SES_REGION_ENDPOINT = 'email.us-east-1.amazonaws.com'

Sending Status Notifications

healtchecks comes with a sendalerts management command, which continuously polls database for any checks changing state, and sends out notifications as needed. Within an activated virtualenv, you can manually run the sendalerts command like so:

$ ./manage.py sendalerts

In a production setup, you will want to run this command from a process manager like supervisor or systemd.

Database Cleanup

With time and use the healthchecks database will grow in size. You may decide to prune old data: inactive user accounts, old checks not assigned to users, records of outgoing email messages and records of received pings. There are separate Django management commands for each task:

• Remove old records from api_ping table. For each check, keep 100 most recent pings:

  $ ./manage.py prunepings
  

• Remove checks older than 2 hours that are not assigned to users. Such checks are by-products of random visitors and robots loading the welcome page and never setting up an account:

  $ ./manage.py prunechecks
  

• Remove records of sent email messages older than 7 days.

  $ ./manage.py pruneemails
  

• Remove user accounts that match either of these conditions:

• Account was created more than a month ago, and user has never logged in. These can happen when user enters invalid email address when signing up.

• Last login was more than a month ago, and the account has no checks. Assume the user doesn't intend to use the account any more and would probably want it removed.

  $ ./manage.py pruneusers
  

When you first try these commands on your data, it is a good idea to test them on a copy of your database, not on the live database right away. In a production setup, you should also have regular, automated database backups set up.

Integrations

Pushover

To enable Pushover integration, you will need to:

• register a new application on https://pushover.net/apps/build
• enable subscriptions in your application and make sure to enable the URL subscription type
• add the application token and subscription URL to hc/local_settings.py, as PUSHOVER_API_TOKEN and PUSHOVER_SUBSCRIPTION_URL