[Bug 1566508] [NEW] autofs races with sssd on startup

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Rafael David Tinoco (inaddy):

[Impact]

 * SSSD is set as started before its responders are active. 
 * Depending services (e.g. autofs) start before those responders are working, and a manual restart is required to make them work after boot
 * This happens with upstart and, with less frequence, systemd 

[Test Case]

 * Configure an LDAP server containing the direct mappings for autofs
 * Configure SSSD to read from that LDAP server
 * Add ‘automount: sss’ to /etc/nsswitch.conf
 * Reboot the machine, login, and try reading the contents of a direct mapping.
 * If the environment has booted correctly the mapping will be available. Otherwise, it will not.

[Regression Potential]

 * This is a cherry-pick from an upstream fix
 * sssd could not start automatically

[Other Info]
 
 * Upstream commit: https://git.fedorahosted.org/cgit/sssd.git/commit/?id=d4063e9a21a4e203bee7e0a0144fa8cabb14cc46


[Original Description]

This report concerns a configuration where autofs and sssd are both
installed, sssd is configured to provide automount maps, and
nsswitch.conf directs autofs to use sssd. In such a configuration autofs
often fails on boot complaining "no mounts in table". This is because
autofs may be started before sssd, or after sssd is started but before
its autofs support is ready. If this happens, one can restart autofs and
it will work fine.

This bug affects other users:
* Bug 40189 "autofs needs to be restarted to pick up some shares" - a very old bug with invalid status, but see last comment #46, complaining about Ubuntu trusty: https://bugs.launchpad.net/ubuntu/+source/autofs/+bug/40189/comments/46
* Link to SSSD-users mailing list, also complaining about Ubuntu trusty: https://lists.fedorahosted.org/pipermail/sssd-users/2015-July/003166.html

$ lsb_release -rd
Description:    Ubuntu 14.04.4 LTS
Release:        14.04

$ apt-cache policy autofs sssd
autofs:
  Installed: 5.0.7-3ubuntu3.2
sssd:
  Installed: 1.11.5-1ubuntu3

$ uname -a
Linux **** 3.13.0-83-generic #127-Ubuntu SMP Fri Mar 11 00:25:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

Workaround:
Edit /etc/init/autofs as shown in attached files (both full file and diff provided). Unfortunately, this modification will work only in this particular configuration, thus it is not a good candidate for a patch.
Explanation:
We have to deal with two problems here:
1. Autofs starts on runlevel [2345], and in effect its startup order in relation to sssd is random. We fix this by changing start stanza to "start on started sssd".
2. Unfortunately this is not enough, because sssd emits started event too early, before its autofs support is ready. To work around this, we add a loop to pre-start script that waits for sssd to start listening on /var/lib/sss/pipes/autofs.

** Affects: sssd (Ubuntu)
     Importance: Medium
     Assignee: Victor Tapia (vtapia)
         Status: In Progress


** Tags: sts
-- 
autofs races with sssd on startup
https://bugs.launchpad.net/bugs/1566508
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