autoscaler.log should be created when the cluster starts up the cluster ring (i.e. very soon after boot, usually before you're able to login). The
member-join event of the handler should write an entry similar to this:
Feb 7 09:27:08 Member data parsed: login1.mycluster.alces.network (10.75.0.44) -- aws_machinetype=t2.large,scheduler_roles=:master:,storage_roles=:master:,access_roles=:master:,role=master,aws_ctime=2017-02-07T09:22:51Z,aws_instanceid=i-02b4b72da83139999
The fact you don't have this log at all is unusual.
Can you confirm which version of Flight Compute you're using please?