Public bug reported:
When SSSD fails to connect to a provider (LDAP, for instance) it creates a
timed event with tevent_add_timer() in order to retry in ~1 min. Tevent relies
on CLOCK_REALTIME, using absolute epoch time, so when the time changes (e.g.
NTP sync) the scheduled event is affected.
Reproducer:
1. Modify the /etc/hosts file to force a failed resolution and restart
sssd
(Tue Oct 25 09:37:14 2016) [sssd[be[openstacklocal]]]
[resolv_gethostbyname_dns_query] (0x0100): Trying to resolve A record of 'ldap'
in DNS
(Tue Oct 25 09:37:14 2016) [sssd[be[openstacklocal]]]
[resolv_gethostbyname_done] (0x0040): querying hosts database failed [5]:
Input/output error
(Tue Oct 25 09:37:14 2016) [sssd[be[openstacklocal]]] [fo_resolve_service_done]
(0x0020): Failed to resolve server 'ldap': Could not contact DNS servers
...
(Tue Oct 25 09:37:14 2016) [sssd[be[openstacklocal]]] [check_online_callback]
(0x0100): Backend returned: (1, 0, <NULL>) [Provider is Offline]
2. Within the ~1 minute window, change the date (date --set) to a
previous time (2 hour in my example). Note: if /etc/resolv.conf or a
network interface is modified, SSSD providers will restart, but the
scheduled retry will be kept.
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]] [recreate_ares_channel]
(0x0100): Initializing new c-ares channel
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]] [recreate_ares_channel]
(0x0100): Destroying the old c-ares channel
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]]
[set_server_common_status] (0x0100): Marking server 'ldap' as 'name not
resolved'
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]] [fo_set_port_status]
(0x0100): Marking port 389 of server 'ldap' as 'neutral'
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]] [fo_resolve_service_send]
(0x0100): Trying to resolve service 'LDAP'
...
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]] [fo_resolve_service_done]
(0x0020): Failed to resolve server 'ldap': Could not contact DNS servers
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]]
[set_server_common_status] (0x0100): Marking server 'ldap' as 'not working'
...
(Tue Oct 25 07:41:46 2016) [sssd[be[openstacklocal]]] [check_online_callback]
(0x0100): Backend returned: (1, 0, <NULL>) [Provider is Offline]
3. Once it gets to the programmed date (2 hours later), it retries:
(Tue Oct 25 09:38:25 2016) [sssd[be[openstacklocal]]]
[set_server_common_status] (0x0100): Marking server 'ldap' as 'name not
resolved'
(Tue Oct 25 09:38:25 2016) [sssd[be[openstacklocal]]] [fo_set_port_status]
(0x0100): Marking port 389 of server 'ldap' as 'neutral'
(Tue Oct 25 09:38:25 2016) [sssd[be[openstacklocal]]] [fo_resolve_service_send]
(0x0100): Trying to resolve service 'LDAP'
...
(Tue Oct 25 09:38:25 2016) [sssd[be[openstacklocal]]] [fo_resolve_service_done]
(0x0020): Failed to resolve server 'ldap': Could not contact DNS servers
(Tue Oct 25 09:38:25 2016) [sssd[be[openstacklocal]]]
[set_server_common_status] (0x0100): Marking server 'ldap' as 'not working'
...
(Tue Oct 25 09:38:25 2016) [sssd[be[openstacklocal]]] [check_online_callback]
(0x0100): Backend returned: (1, 0, <NULL>) [Provider is Offline]
** Affects: sssd (Ubuntu)
Importance: Undecided
Status: New
** Tags: sts
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https://bugs.launchpad.net/bugs/1641875
Title:
Scheduled events (e.g. LDAP connection retries) are affected by clock
adjustments
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