Comment 24 for bug 1506112

Reviewed: https://review.openstack.org/367245
Committed: https://git.openstack.org/cgit/openstack/fuel-web/commit/?id=b1da633fdac0f9eab6ee05d902dfbd3e9d57be05
Submitter: Jenkins
Branch: stable/7.0

commit b1da633fdac0f9eab6ee05d902dfbd3e9d57be05
Author: Rodion Tikunov <email address hidden>
Date: Mon Jun 20 18:48:12 2016 +0300

    fix race with syslog while renaming remote log dir

    When a node gets new name nailgun renames log directory which had name
    in form of <IP> to <node name> and then creates symlink <IP> ->
    <node name>. The problem is that node is still active at this moment
    and sends some logs to syslog on master node. So when we renamed <IP>
    to <node name> and haven't created symlink name syslog may find
    missing log dir and it creates it again in this case. Then nailgun
    tries to create symlink and fails.

    To avoid this situation this patch adds attempts to remove a directory
    and create symlink until symlink will being successfully created.

    Approach used in master does not work in <=8.0. In MOS=<8.0 nailgun
    and rsyslog work in different PID namespaces and can not interact
    with each other by signals.

    Change-Id: Ia402508dac427909aa1593787f9aba54f2df05e4
    Closes-bug: #1506112
    (cherry picked from commit 11ce99ab4e46fad061edd99c6342ea647f0acd75)