The LACT Daemon exposes a JSON API over a unix socket, available on /var/run/lactd.sock. You can configure who has access to the socket in /etc/lact/config.yaml in the daemon.admin_groups field.
The API expects newline-separated JSON objects, and returns a JSON object for every request.
The general format of requests looks like:
{"command": "command_name", "args": {}}
Note that the type of args depends on the specific request, and may be ommited in some cases.
The response looks like this:
{"status": "ok|error", "data": {}}
Same as args in requests, data can be of a different type and may not be present depending on the specific request.
You can try sending commands to socket interactively with ncat:
echo '{"command": "list_devices"}' | ncat -U /run/lactd.sock
Example response:
{"status":"ok","data":[{"id":"1002:687F-1043:0555-0000:0b:00.0","name":"Vega 10 XL/XT [Radeon RX Vega 56/64]"}]}
For the full list of available commands and responses, you can look at the source code of the schema: requests, the basic response structure and all possible types.
It should also be fairly easy to figure out the API by trial and error, as the error message are quite verbose:
echo '{"command": "test"}' | ncat -U /run/lactd.sock
{"status":"error","data":"Failed to deserialize request: unknown variant `test`, expected one of `ping`, `list_devices`, `system_info`, `device_info`, `device_stats`, `device_clocks_info`, `set_fan_control`, `set_power_cap`, `set_performance_level`, `set_clocks_value` at line 1 column 18"}
If you want to connect to the socket from a Rust program, you can simply import either the lact-client or lact-schema (if you want to write a custom client) crates from this repository.