How can I receive a notification if one of my services (eg. MariaDB) dies?

Questions & Answers
#1

I’d like to get an alert if a service dies or is unreachable.

#2

One way of doing this would be to set up a cron job to periodically ping MariaDB and send an e-mail to a specified address based on that ping status.

Allow outgoing emails in environment configuration (if necessary)

Email support can be set up in each environment, and by default it is already enabled on master and disabled elsewhere. You can enable email through the environment configuration settings in the Web UI, or by using the Platform.sh CLI:

$ platform environment:info enable_smtp true

You can find more information about email on Platform.sh in the documentation.

Set up a cron job in .platform.app.yaml to ping MariaDB

In your .platform.app.yaml set up a cron job for the service you want to check the status of. Here an exit code 0 means our ping was successful and MariaDB is running fine.

# proj_dir/.platform.app.yaml
...

crons:
    # Check MySQL/MariaDB status
    mysql_status:
        # Runs every 10 minutes
        spec: '*/10 * * * *'
        cmd: |
            # Pings MySQL/MariaDB, retrieves status message
            status=$(mysqladmin -h mysql.internal ping)
            # Saves the exit code
            check=$?
            if [ $check = 0 ]; then
                # Run mail php file, passing service and status message
                php notifications/service_notify.php --service "MySQL" --status "$status"
            fi

relationships:
    mysql: "mysql:mysql"
    
...

If you named your relationships differently, you will need to modify mysql.internal to the correct name. (For example, database.internal, etc.)

ping() may not be the most robust test case, and is only used here for a simple example. Check the mysqladmin documentation to find the test that best suits your needs.

Write a php file that handles mail() for the ping status

In the project directory, create a subdirectory called notifications, and within that subdirectory write a service_notify.php file:

// proj_dir/notifications/service_notify.php
<?php

// Retrieve opts
$shortopts  = "";

$longopts  = array(
    "service:",
    "status:",
);
$options = getopt($shortopts, $longopts);

$service = $options["service"];
$status = $options["status"];

// Project environment variables
$projectid = getenv('PLATFORM_PROJECT');
$environment = getenv('PLATFORM_ENVIRONMENT');
$app = getenv('PLATFORM_APPLICATION_NAME');

// Mail Contents
$to      = 'you@example.com';
$subject = sprintf('Platform.sh Service Status Update: %s DOWN on Project %s', $service, $projectid);
$headers = 'From: webmaster@example.com' . "\r\n" .
    'X-Mailer: PHP/' . phpversion();

// Create the message
$message = <<<EOT
There has been a change in a service status:

    * Service: $service

    * Status: $status

    on

    * Project: $projectid

    * Application: $app

    * Environment: $environment

EOT;

// Send it
mail($to, $subject, $message, $headers);

?>

Verify

Our project is set up to email you@example.com with the status of a successful ping on mysql.internal every 10 minutes. That status email will look like this.

webmaster@example.com
Platform.sh Service Status Update: MySQL DOWN on Project <project ID>
To: you@example.com
--------------------------------------------------------------------------

There has been a change in a service status:

   * Service: MySQL

   * Status: mysqld is alive

   on

   * Project: <project ID>

   * Application: app

   * Environment: master-7rqtwti

Set up MySQL down notifications

The preceeding steps send out an e-mail that includes the status message of a successful ping on mysql.internal. That is, it will e-mail us every ten minutes to let us know everything is fine.

To modify the notification to let us know that MySQL has died or is unreachable, modify the if statement in .platform.app.yaml cron job to:

            # If not successful (1)
            if [ $check != 0 ]; then
                # Run mail php file, passing service and status message
                php notifications/service_notify.php --service "MySQL" --status "$status"
            fi

This way, when a ping delivers an exit code of 1, an email is sent!