backup-rsync

#! /bin/python
import sys,os,time,glob,shutil
import subprocess as sp

def backup (src,dst):
	src = sys.argv[1]
	exclude_file = os.path.join (src,'.backup-exclude')
	dst = sys.argv[2]
	dst_dir = os.path.join (dst,'%i'%time.time())
	lnk_dir = get_old_backups (dst)[-1]

	try:
		rsync_call = ['rsync','-aHAxXP','--exclude=lost+found',src,dst_dir]
		if lnk_dir:
			rsync_call.append ('--link-dest='+lnk_dir)
		if ':' in dst:
			rsync_call.append ('-M--fake-super')
		if os.path.exists (exclude_file):
			rsync_call.append ('--exclude-from='+exclude_file)
		print (' '.join (rsync_call))
		sp.check_call (rsync_call)
	except sp.CalledProcessError as e:
		print (e)
		sys.exit (1)
	prune_backups (dst)


def get_old_backups (dst):
	if os.path.isdir (dst):
		old_backups = list(map (os.path.abspath, glob.glob (dst+'/*')))
	else:
		host,directory = dst.split(':',1)
		directory = directory if directory.startswith('/') else '$PWD/'+directory
		find_call = ['ssh',host,'find',directory,'-mindepth','1','-maxdepth','1',
		             '-type','d']
		old_backups = sp.check_output(find_call).decode('utf8').strip().split('\n')

	if not len (old_backups): return
	return sorted(old_backups)

def prune_backups (dst):
	old_backups = get_old_backups (dst)
	remote = not os.path.isdir(dst)
	if remote:
		host,directory = dst.split(':',1)

	while len (old_backups) > 3:
		print ('Pruning old backup '+old_backups[0])
		if remote:
			try:
				sp.call (['ssh',host,'rm','-r',old_backups.pop (0)])
			except sp.CalledProcessError as e:
				print ('Failed to delete old backup:\n'+e)
		else:
			shutil.rmtree (old_backups.pop(0))



if __name__ == '__main__':
	if len(sys.argv) != 3 or '-h' in sys.argv:
		print ('Usage: %s rsyncsource rsynctarget'%sys.argv[0])
		sys.exit ()

	backup (sys.argv[1],sys.argv[2])