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 3.6+
Django 3
PostgreSQL or MySQL

Setting Up for Development

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

install dependencies (Debian/Ubuntu)

  $ sudo apt-get update
  $ sudo apt-get install -y gcc python3-dev python3-venv

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):
```
  $ python3 -m venv hc-venv
  $ source hc-venv/bin/activate
```

check out project code:

  $ git clone https://github.com/healthchecks/healthchecks.git

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

  $ pip install -r healthchecks/requirements.txt

healthchecks is configured to use a SQLite database by default. To use PostgreSQL or MySQL database, create and edit hc/local_settings.py file. There is a template you can copy and edit as needed:
```
  $ cd ~/webapps/healthchecks
  $ cp hc/local_settings.py.example hc/local_settings.py
```

create database tables and the superuser account:

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

run development server:
```
  $ ./manage.py runserver
```

The site should now be running at http://localhost:8000. To access Django administration site, log in as a super user, then visit http://localhost:8000/admin

Configuration

Site configuration is loaded from environment variables. This is done in hc/settings.py. Additional configuration is loaded from hc/local_settings.py file, if it exists. You can create this file (should be right next to settings.py in the filesystem) and override settings, or add extra settings as needed.

Configurations settings loaded from environment variables:

Environment variable	Default value	Notes
SECRET_KEY	`"---"`
DEBUG	`True`	Set to `False` for production
ALLOWED_HOSTS	`*`	Separate multiple hosts with commas
DEFAULT_FROM_EMAIL	`"healthchecks@example.org"`
USE_PAYMENTS	`False`
REGISTRATION_OPEN	`True`
DB	`"sqlite"`	Set to `"postgres"` or `"mysql"`
DB_HOST	`""` (empty string)
DB_PORT	`""` (empty string)
DB_NAME	`"hc"` (PostgreSQL, MySQL) or `"/path/to/project/hc.sqlite"` (SQLite)	For SQLite, specify the full path to the database file.
DB_USER	`"postgres"` or `"root"`
DB_PASSWORD	`""` (empty string)
DB_CONN_MAX_AGE	`0`
DB_SSLMODE	`"prefer"`	PostgreSQL-specific, details
DB_TARGET_SESSION_ATTRS	`"read-write"`	PostgreSQL-specific, details
EMAIL_HOST	`""` (empty string)
EMAIL_PORT	`"587"`
EMAIL_HOST_USER	`""` (empty string)
EMAIL_HOST_PASSWORD	`""` (empty string)
EMAIL_USE_TLS	`"True"`
EMAIL_USE_VERIFICATION	`"True"`
SITE_ROOT	`"http://localhost:8000"`
SITE_NAME	`"Mychecks"`
MASTER_BADGE_LABEL	`"Mychecks"`
PING_ENDPOINT	`"http://localhost:8000/ping/"`
PING_EMAIL_DOMAIN	`"localhost"`
PING_BODY_LIMIT	10000	In bytes. Set to `None` to always log full request body
DISCORD_CLIENT_ID	`None`
DISCORD_CLIENT_SECRET	`None`
SLACK_CLIENT_ID	`None`
SLACK_CLIENT_SECRET	`None`
PUSHOVER_API_TOKEN	`None`
PUSHOVER_SUBSCRIPTION_URL	`None`
PUSHOVER_EMERGENCY_RETRY_DELAY	`300`
PUSHOVER_EMERGENCY_EXPIRATION	`86400`
PUSHBULLET_CLIENT_ID	`None`
PUSHBULLET_CLIENT_SECRET	`None`
TELEGRAM_BOT_NAME	`"ExampleBot"`
TELEGRAM_TOKEN	`None`
TWILIO_ACCOUNT	`None`
TWILIO_AUTH	`None`
TWILIO_FROM	`None`
TWILIO_USE_WHATSAPP	`"False"`
PD_VENDOR_KEY	`None`
TRELLO_APP_KEY	`None`
MATRIX_HOMESERVER	`None`
MATRIX_USER_ID	`None`
MATRIX_ACCESS_TOKEN	`None`
APPRISE_ENABLED	`"False"`
SHELL_ENABLED	`"False"`

Some useful settings keys to override are:

SITE_ROOT is used to build fully qualified URLs for pings, and for use in emails and notifications. Example:

SITE_ROOT = "https://my-monitoring-project.com"

SITE_NAME has the default value of "Mychecks" and is used throughout the templates. Replace it with your own name to personalize your installation. Example:

SITE_NAME = "My Monitoring Project"

REGISTRATION_OPEN controls whether site visitors can create new accounts. Set it to False if you are setting up a private healthchecks instance, but it needs to be publicly accessible (so, for example, your cloud services can send pings).

If you close new user registration, you can still selectively invite users to your team account.

EMAIL_USE_VERIFICATION enables/disables the sending of a verification link when an email address is added to the list of notification methods. Set it to False if you are setting up a private healthchecks instance where you trust your users and want to avoid the extra verification step.

PING_BODY_LIMIT sets the size limit in bytes for logged ping request bodies. The default value is 10000 (10 kilobytes). You can remove the limit altogether by setting this value to None.

Database Configuration

Database configuration is loaded from environment variables. If you need to use a non-standard configuration, you can override the database configuration in hc/local_settings.py like so:

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'},
        'OPTIONS': {
            ... your custom options here ...
        }
    }
}

Accessing Administration Panel

healthchecks comes with Django's administration panel where you can manually view and modify user accounts, projects, checks, integrations etc. To access it,

if you haven't already, create a superuser account: ./manage.py createsuperuser
log into the site using superuser credentials
in the top navigation, "Account" dropdown, select "Site Administration"

Sending Emails

healthchecks must be able to send email messages, so it can send out login links and alerts to users. Environment variables can be used to configure SMTP settings, or your may put your SMTP server configuration in hc/local_settings.py like so:

EMAIL_HOST = "your-smtp-server-here.com"
EMAIL_PORT = 587
EMAIL_HOST_USER = "username"
EMAIL_HOST_PASSWORD = "password"
EMAIL_USE_TLS = True

For more information, have a look at Django documentation, Sending Email section.

Receiving Emails

healthchecks comes with a smtpd management command, which starts up a SMTP listener service. With the command running, you can ping your checks by sending email messages to your-uuid-here@my-monitoring-project.com email addresses.

Start the SMTP listener on port 2525:

$ ./manage.py smtpd --port 2525

Send a test email:

$ curl --url 'smtp://127.0.0.1:2525' \
    --mail-from 'foo@example.org' \
    --mail-rcpt '11111111-1111-1111-1111-111111111111@my-monitoring-project.com' \
    -F '='

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 old records of sent notifications. For each check, remove notifications that are older than the oldest stored ping for same check.
```
$ ./manage.py prunenotifications
```
Remove user accounts that match either of these conditions:
- Account was created more than 6 months ago, and user has never logged in. These can happen when user enters invalid email address when signing up.
- Last login was more than 6 months 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
```
Remove old records from the api_tokenbucket table. The TokenBucket model is used for rate-limiting login attempts and similar operations. Any records older than one day can be safely removed.
```
$ ./manage.py prunetokenbucket
```
Remove old records from the api_flip table. The Flip objects are used to track status changes of checks, and to calculate downtime statistics month by month. Flip objects from more than 3 months ago are not used and can be safely removed.
```
$ ./manage.py pruneflips
```

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

Discord

To enable Discord integration, you will need to:

register a new application on https://discordapp.com/developers/applications/me
add a redirect URI to your Discord application. The URI format is SITE_ROOT/integrations/add_discord/. For example, if you are running a development server on localhost:8000 then the redirect URI would be http://localhost:8000/integrations/add_discord/
Look up your Discord app's Client ID and Client Secret. Put them in DISCORD_CLIENT_ID and DISCORD_CLIENT_SECRET environment variables.

Pushover

Pushover integration works by creating an application on Pushover.net which is then subscribed to by Healthchecks users. The registration workflow is as follows:

On Healthchecks, the user adds a "Pushover" integration to a project
Healthchecks redirects user's browser to a Pushover.net subscription page
User approves adding the Healthchecks subscription to their Pushover account
Pushover.net HTTP redirects back to Healthchecks with a subscription token
Healthchecks saves the subscription token and uses it for sending Pushover notifications

To enable the Pushover integration, you will need to:

Register a new application on Pushover via https://pushover.net/apps/build.
Within the Pushover 'application' configuration, enable subscriptions. Make sure the subscription type is set to "URL". Also make sure the redirect URL is configured to point back to the root of the Healthchecks instance (e.g., http://healthchecks.example.com/).
Put the Pushover application API Token and the Pushover subscription URL in PUSHOVER_API_TOKEN and PUSHOVER_SUBSCRIPTION_URL environment variables. The Pushover subscription URL should look similar to https://pushover.net/subscribe/yourAppName-randomAlphaNumericData.

Create a Telegram bot by talking to the BotFather. Set the bot's name, description, user picture, and add a "/start" command.
After creating the bot you will have the bot's name and token. Put them in TELEGRAM_BOT_NAME and TELEGRAM_TOKEN environment variables.
Run settelegramwebhook management command. This command tells Telegram where to forward channel messages by invoking Telegram's setWebhook API call:
```
$ ./manage.py settelegramwebhook
Done, Telegram's webhook set to: https://my-monitoring-project.com/integrations/telegram/bot/
```

For this to work, your SITE_ROOT needs to be correct and use "https://" scheme.

Apprise

To enable Apprise integration, you will need to:

ensure you have apprise installed in your local environment:

pip install apprise

enable the apprise functionality by setting the APPRISE_ENABLED environment variable.

Shell Commands

The "Shell Commands" integration runs user-defined local shell commands when checks go up or down. This integration is disabled by default, and can be enabled by setting the SHELL_ENABLED environment variable to True.

Note: be careful when using "Shell Commands" integration, and only enable it when you fully trust the users of your Healthchecks instance. The commands will be executed by the manage.py sendalerts process, and will run with the same system permissions as the sendalerts process.

Running in Production

Here is a non-exhaustive list of pointers and things to check before launching a Healthchecks instance in production.

Environment variables, settings.py and local_settings.py.
- DEBUG. Make sure it is set to False.
- ALLOWED_HOSTS. Make sure it contains the correct domain name you want to use.
- Server Errors. When DEBUG=False, Django will not show detailed error pages, and will not print exception tracebacks to standard output. To receive exception tracebacks in email, review and edit the ADMINS and SERVER_EMAIL settings. Another good option for receiving exception tracebacks is to use Sentry.
Management commands that need to be run during each deployment.
- This project uses Django Compressor to combine the CSS and JS files. It is configured for offline compression – run the manage.py compress command whenever files in the /static/ directory change.
- This project uses Django's staticfiles app. Run the manage.py collectstatic command whenever files in the /static/ directory change. This command collects all the static files inside the static-collected directory. Configure your web server to serve files from this directory under the /static/ prefix.
- Database migration should be run after each update to make sure the database schemas are up to date. You can do that with ./manage.py migrate.
Processes that need to be running constantly.
- manage.py runserver is intended for development only. Do not use it in production, instead consider using uWSGI or gunicorn.
- Make sure the manage.py sendalerts command is running and can survive server restarts. On modern linux systems, a good option is to define a systemd service for it.
General
- Make sure the database is secured well and is getting backed up regularly
- Make sure the TLS certificates are secured well and are getting refreshed regularly
- Have monitoring in place to be sure the Healthchecks instance itself is operational (is accepting pings, is sending out alerts, is not running out of resources).

rbabaee/healthchecks