dovecot - Dec 2013 - Dsync error: Couldn't drop privileges: getgrnam

Hi,

I upgraded (in place upgrade, preserving my dovecot configs) to a newer 
release of ubuntu in order to gain access to slightly newer Dovecot 
release and be able to use Dsync for migration from Cyrus, here is my 
doveconf -n output:

# 2.1.7: /etc/dovecot/dovecot.conf
# OS: Linux 3.5.0-44-generic x86_64 Ubuntu 12.10
auth_debug = yes
auth_default_realm = whatever.com
auth_master_user_separator = *
auth_socket_path = /var/run/dovecot/auth-master
imapc_features = rfc822.size
imapc_host = oldmail.whatever.com
imapc_master_user = cyradmin
imapc_password = <password hidden>
mail_chroot = /var/vmail
mail_debug = yes
mail_gid = 5000
mail_location = maildir:~/Maildir
mail_prefetch_count = 20
mail_privileged_group = vmail
mail_uid = 5000
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope 
encoded-character vacation subaddress comparator-i;ascii-numeric 
relational regex imap4flags copy include variables body enotify 
environment mailbox date ihave
passdb {
   args = /etc/dovecot/master-users
   driver = passwd-file
   master = yes
}
passdb {
   args = /etc/dovecot/dovecot-ldap.conf.ext
   driver = ldap
}
plugin {
   sieve = ~/.dovecot.sieve
   sieve_dir = ~/sieve
}
protocols = " imap lmtp sieve pop3"
service auth-worker {
   user = $default_internal_user
}
service auth {
   unix_listener /var/spool/postfix/private/auth {
     mode = 0666
   }
   unix_listener auth-userdb {
     group = dovecot
     mode = 0600
     user = dovecot
   }
}
service lmtp {
   unix_listener /var/spool/postfix/private/dovecot-lmtp {
     group = postfix
     mode = 0600
     user = postfix
   }
}
service managesieve-login {
   inet_listener sieve {
     port = 4190
   }
}
ssl_cert = <cert
ssl_key = <cert
userdb {
   args = uid=vmail gid=vmail home=/domain/%1d/%d/%1n/%n 
allow_all_users=yes
   driver = static
}
protocol lmtp {
   postmaster_address = post at whatever.com
}
protocol imap {
   mail_max_userip_connections = 10
}
protocol pop3 {
   pop3_uidl_format = %v.%u
}

And the command I am using to (attempt) a mailbox sync:

doveadm -o mail_fsync=never backup -R -u alantestuser at whatever.com 
imapc:

Produces this output:

dsync(alantestuser at whatever.com): Error: user 
alantestuser at whatever.com: Couldn't drop privileges: getgrnam(vmail) 
failed: No such file or directory (in mail_privileged_group setting)
dsync(alantestuser at whatever.com): Fatal: User init failed

mail.log shows this:

Dec  5 21:10:54 newmailserver dovecot: auth: Debug: Loading modules 
from directory: /usr/lib/dovecot/modules/auth
Dec  5 21:10:54 newmailserver dovecot: auth: Debug: Loading modules 
from directory: /usr/lib/dovecot/modules/auth
Dec  5 21:10:54 newmailserver dovecot: auth: Debug: Module loaded: 
/usr/lib/dovecot/modules/auth/libauthdb_ldap.so
Dec  5 21:10:54 newmailserver dovecot: auth: Debug: passwd-file 
/etc/dovecot/master-users: Read 1 users in 0 secs
Dec  5 21:10:54 newmailserver dovecot: auth: Debug: master in: 
USER#0111#011alantestuser at whatever.com#011service=doveadm
Dec  5 21:10:54 newmailserver dovecot: auth: Debug: master out: 
USER#0111#011alantestuser at
whatever.com#011uid=5000#011gid=5000#011home=/domain/w/whatever.com/a/alantestuser

I followed this doc (which could use a little fleshing out, I will be 
happy to do it once I get a grasp on this!): 
http://wiki2.dovecot.org/Migration/Dsync

Thanks in advance!

/Alan

On 5.12.2013, at 22.18, Alan McGinlay - SICS <alanm at sics.se> wrote:
> mail_privileged_group = vmail
..
> mail_location = maildir:~/Maildir
..
> dsync(alantestuser at whatever.com): Error: user alantestuser at
whatever.com: Couldn't drop privileges: getgrnam(vmail) failed: No such file
or directory (in mail_privileged_group setting)
You don?t have vmail group in your system? Either create it or remove this
setting. Most likely you want to remove it, since this setting was meant only
for mbox format, while you?re using maildir.

Alan McGinlay wrote:
> Can't believe I'm the only one with this error, googled it and
there is
> nothing. Sorry to whine but I am getting desperate here!
I googled "safe_mkstemp permission denied" and first hit is this
thread

 	dovecot.org/list/dovecot/2010-August/052319.html

which mentions this error coming about from chrooting users.  Looking back
on your post, I see

 	http://www.dovecot.org/list/dovecot/2013-December/093900.html

 	mail_chroot = /var/vmail

As long as your desperate, maybe try leaving this setting empty?
(This doesn't explain why it's not deterministic though.)   Try
process traces -- I do when I'm stumped.

Joseph Tam <jtam.home at gmail.com>