[nfr] Add an --include option

[sourcejedi]

I'm using bup and want to switch to bup-cron for obvious reasons. I don't backup firefox because it seems like unecessary churn from history & state-saving (firefox crash recovery), plus we have Firefox Sync. But I do back up my 400Kb of bookmarks. I can't see how to do this in bup-cron, while I can with bup:

bup index "$HOME_DIR" --exclude "$HOME_DIR"/.mozilla
bup index "$HOME_DIR"/.mozilla/firefox/*/bookmarkbackups

I think bup-cron should have --include. Possibly bup-index could implement it, and bup-cron just pass it through :). I don't want to pass multiple paths with bup-cron -p, because then firefox is in a different backup to my other dotfiles.

(Am also slightly disturbed by the semantics illustrated in the example config file. Why are there multiple overlapping paths? Because implementing --snapshot effectively requires --xdev. But this means --snapshot affects what's being backed up. Strawman hack: implement --xdev if it's not already, and require it to be explicitly passed for --snapshot. Or snapshot recursively. Hmm, I wonder if other Windows backup programs handle mountpoints correctly with VSS :)).

[anarcat]

i would rather avoid a clunky --include and allow specifying multiple paths correctly.

if you look in the source code in bup_cron/__init__.py:1034 (https://github.com/anarcat/bup-cron/blob/master/bup_cron/__init__.py#L1034) you will see why: basically, we can't pass those paths all at once to bup index because we were having problems with bup index -x / /var.

we could however loop on bup index and then call bup save only once, but then the assumption is that each path provided is its own filesystem...

--include would require serious re-engineering here... there is already some work to be done to cleanup the snapshot/filesystem detection code here, as mentionned here:

pfrouleau/bup@1244a2d#commitcomment-7866283

but this is, yes, yet another oddity. can't hide all the weird bup corner cases here... ;)