There is a bunch of output at the last stage of imageBuilt, which ends with
5,548,912 0% 22.61MB/s 0:00:00 (xfr#3, to-chk=0/24715) loop deleted : /dev/loop0
This is fine interactively, but when a propellor job fails and I get email, it includes roughly 2500 similar lines, which is not so great. It would be nice if it could detect being interactive, or maybe just be quiet all the time.
This output comes from Propellor.Property.Rsync.rsync because it runs
rsync --info=progress2.I suppose it could check if stdout is going to a tty and only enable it then.
However, I do have some code I wrote once that uses propellor to build a live disk image that runs propellor to partition and then used the rsync property to copy the live image to disk (followed by applying more properties to it to configure the system it installed). And that code caught the rsync progress output and used it to display some kind of graphical progress bar. That kind of thing would be broken by such a change. (That's in my secret-project repository.)
I don't know of anyone using such a thing in production, so I think it would be ok to just have a
PROPELLOR_VERBOSEPROGRESS=1that such code could use to enable verbose progress from rsync etc, and otherwise disable it when stdout is not a tty.