Monitoring
OpenMetrics (e.g. Prometheus)
OpenMetrics is an open standard for exposing metrics data (numerical time series) in a text-based format over HTTP. Originally developed by the Prometheus community, several other observability platforms also accept this format, including Grafana Mimir, VictoriaMetrics, Thanos, InfluxDB, Datadog, and New Relic.
Custom metrics
Halon has a comprehensive set of standard metrics that are presented in OpenMetrics format.
Monitoring with Slack
You can use Slack to monitor for events that happen on the Halon MTA, like when rate limits are exceeded for example.
Monitoring with Amazon CloudWatch
This article describes how to configure Halon Engage & Protect (runnning in an EC2 instance) to publish custom metrics such as queue sizes to Amazon CloudWatch.