monitor and alert. Get alerted when services go down or metrics go crazy.
Self-hosted, easily-deployable monitoring and alerts service - like a lightweight PagerDuty

Cabot is a free, open-source, self-hosted infrastructure monitoring platform that provides some of the best features of PagerDuty, Server Density, Pingdom and Nagios without their cost and complexity. (Nagios, I'm mainly looking at you.)

It provides a web interface that allows you to monitor services (e.g. "Stage Redis server", "Production ElasticSearch cluster") and send telephone, sms or hipchat/email alerts to your on-duty team if those services start misbehaving or go down - all without writing a line of code. Best of all, you can use data that you're already pushing to Graphite/statsd to generate alerts, rather than implementing and maintaining a whole new system of data collectors.

• Cabot @ GitHub.

An open-source service monitoring system and time series database.

An open source, feature rich metrics dashboard and graph editor for
Graphite, InfluxDB & OpenTSDB.