Exit code 0 when terminating in the WebUI

[maleadt]

The documentation states that buildkite-agent should exit with code 255 if "The agent was gracefully terminated". I assumed that this would be the case when clicking the "Stop Agent" button in the WebUI, however, it seems like that simply exits with code 0.

This is a problem for me, because I run buildkite-agent in one-shot mode, i.e., passing --disconnect-after-job. In that case, it's impossible to distinguish between a completed or canceled job (both exiting with code 0, as expected) and one where I requested the agent to terminate (where I expected code 255). I would like this information to do something like:

while true; do
    buildkite-agent --disconnect-after-job
    if [[ ret -eq 255]; then
        break
    fi
done

FYI, I'm using --disconnect-after-job for containerization purposes, running all of buildkite-agent under sandbox-exec or docker.