This has side effects that will affect the caller.

You probably should avoid this unshift and do

```perl
return $self->run_command([qw(/usr/bn/ceph -f json --cluster), $self->{cluster}, @$command]);
```

Also, don't use `$self` for passing parameters. They act like globals and are difficult to track. If you got the `cluster` from the profile pass it as another parameter.