Load Testing with Koi Pond

This post details the design and implementation of Koi Pond, a load-testing tool for Slack. It describes how Koi Pond spins up slimmed-down Slack clients ('koi') that establish websocket connections and send API calls, mirroring real client behavior. The post explains two key concepts: 'behaviors' for simulating API usage at realistic frequencies and 'formations' for testing mass user actions like viewing and reacting to messages to simulate 'thundering herd' scenarios. It contrasts Koi Pond with previous tools like Puppet Show and API Blast, highlighting its cost-efficiency and ability to test both backend and real-time services.