It's also named after pants.
It behaves like a swarm of collectd agents firing a fixed number of metrics at a fixed interval to your carbon-compatible endpoint. The number of agents increase over time until a maximum number is reached. At any given time, you can pause the spawning of new agents by sending
SIGUSR1. Spawning can be resumed by doing the same.
$ go get github.com/gorsuch/haggar
$ haggar -h Usage of haggar: -agents=100: max number of agents to run concurrently -carbon="localhost:2003": address of carbon host -flush-interval=10s: how often to flush metrics -jitter=10s: max amount of jitter to introduce in between agent launches -metrics=10000: number of metrics for each agent to hold -prefix="haggar": prefix for metrics -spawn-interval=10s: how often to gen new agents