[Libguestfs] getting guestfs_rsync_out to work

[Jeff Brower]

Richard-

>> Per this page
>>
>>   https://rwmj.wordpress.com/2013/04/22/using-rsync-with-libguestfs/
>>
>> We are trying to get the libguestfs API guestfs_rsync_out to work.  We’ve tried combinations similar to:
>>
>>   guestfs_rsync_out(g, “/HostShared”, “rsync://root@10.0.1.90:2999/backup/ -av”, -1)
>>
>> surrounding it with APIs as in the recipe examples, for example replacing libguestfs_cat(), with no luck. In the
>> above
>> example the "backup" rsync module name matches the script on Richard's wordpress.com blog page (above link).
>> Typically in the rsync daemon log we see something like:
>>
>>   receiving file list
>>   sent 17 bytes received 24 bytes total size 0
>>
>> but no data is transferred. We are successful using rsync from the Linux command line, and we can get libguestfs
>> APIs
>> like guestfs_cat() to work fine. But we’ve had zero luck with rsync_out over the last week.
>
> I think it's really hard to diagnose problems without turning on
> debugging in libguestfs:
>
> http://libguestfs.org/guestfs-faq.1.html#how-do-i-debug-when-using-the-api
>
>> Unfortunately there are no actual API examples online, no
>> “recipes” on the libguestfs.org site, etc.  Does anyone know
>> where there are some actual libguestfs_rsync_out() working examples?
>
> The only example I can point to is this test:
>
> https://github.com/libguestfs/libguestfs/blob/master/tests/rsync/test-rsync.sh

Thanks very much.  In our example, the libguestfs API syntax required turns out to be:

  guestfs_rsync_out(g, "/Win7Folder", "rsync://root@10.0.1.90:2999/backup", GUESTFS_RSYNC_OUT_ARCHIVE, 1, -1)

This produces a trace result:

  libguestfs: trace: rsync_out "/Win7Folder" "rsync://root@10.0.1.90:2999/backup" "archive:true"

Also, to avoid chgrp and other permission related messages, we had to add:

  uid = 0
  gid = 0

in our rsyncd.conf file (we are running rsync daemaon as root).

Now we are testing guestfs_rsync_out() in a loop that runs every 1 sec.  We hope to achieve continuous synchronization
with a live Win7 guest.  As I mentioned before, we're only reading from the Win7 guest, and not a lot of data is
involved, maybe a few files up to 50 MByte.  These files are not changing size, just contents.

-Jeff