So there is already the FastLED light component: https://esphomelib.com/esphomeyaml/index.html#light-components which handles these individually addressable LED strips.
But that integration doesn't have too many light effects yet. I'm not a big fan of modifying the JSON payload for the MQTT JSON light though, as that would require special automations in the Hass configuration. I'm planning to rework the effects in esphomelib a bit to allow at least for some parameterization of settings. The syntax would look like this:
yaml light: - platform: fastled_clockless # ... effects: - rainbow: name: "Slow Rainbow Effect" speed: 42s # or whatever this option would be called - rainbow: name: "Fast Rainbow Effect" speed: 1s # or when no parameters specified defaults to some values - rainbow: - random: - colorwheel:
This way the user has complete controls of which effects can be used and can even parameterize them quite quickly without messing with sending custom MQTT messages in HA.