Alerter: Send notifications to administrators via the right channels

When it’s time for a monitoring tool to push an alert to an administrator, it calls the alert command with the appropriate arguments:

• --team - either ptp or mayfirst, depending on which team should receive the alert.

• --priority - either critical or warning depending on the severity (see the monitor page for an explanation of the difference between the two)

• --body - the body of the message to send.

• --subject - optionally provide a subject (only used for email alerts)

The alert command consults the /etc/alerter.yml file to determine how to send the alert. It currently supports sending via email or signal.

The alerter system depends on a working smtp service and the signal-cli service. We also have a document explaining what to do when we get an alert.