statusStepFor method
The daemon, not the CLI.
docker --version answers from the client binary alone and says nothing
about whether anything is running — it prints a version perfectly happily
on a host whose daemon is stopped. docker info has to reach the daemon,
so it is the question worth asking, and its server version is what the
badge shows.
Implementation
@override
CommandStep? statusStepFor(String osName) =>
const CommandStep('docker', ['info', '--format', '{{.ServerVersion}}']);