Bug 613085
Summary: | Having no nscd can break early starting services | |||
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Product: | [Fedora] Fedora | Reporter: | Colin.Simpson | |
Component: | sssd | Assignee: | Stephen Gallagher <sgallagh> | |
Status: | CLOSED NOTABUG | QA Contact: | Fedora Extras Quality Assurance <extras-qa> | |
Severity: | medium | Docs Contact: | ||
Priority: | low | |||
Version: | 13 | CC: | dpal, jhrozek, sbose, sgallagh, ssorce | |
Target Milestone: | --- | |||
Target Release: | --- | |||
Hardware: | All | |||
OS: | Linux | |||
Whiteboard: | ||||
Fixed In Version: | Doc Type: | Bug Fix | ||
Doc Text: | Story Points: | --- | ||
Clone Of: | ||||
: | 613096 (view as bug list) | Environment: | ||
Last Closed: | 2010-11-09 16:49:45 UTC | Type: | --- | |
Regression: | --- | Mount Type: | --- | |
Documentation: | --- | CRM: | ||
Verified Versions: | Category: | --- | ||
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | ||
Cloudforms Team: | --- | Target Upstream Version: | ||
Embargoed: | ||||
Bug Depends On: | ||||
Bug Blocks: | 613096 |
Description
Colin.Simpson
2010-07-09 16:31:43 UTC
I am not sure that it will eliminate all the cases when the nscd would have to be considered. We will still look into replacing it in a long run as mentioned in https://fedorahosted.org/sssd/ticket/357 . Thanks for the workaround. Thanks. I look forward to the day when we have no more nscd (In reply to comment #2) > Thanks. > > I look forward to the day when we have no more nscd External contributions are always welcome :-) This is not a bug in SSSD. If there are services that are not rereading /etc/resolv.conf when it changes, this is a bug in that service, or libc. While I personally believe that this is a bug in glibc, the official word on this is that individual applications and services should be required to call the glibc res_init() function when the /etc/resolv.conf changes, in order to reread it. The fact that nscd mitigates this problem is actually not reliable. NSCD is merely holding on to the cache it had when the system was shut down, but there is in fact no guarantee that this is the correct resolv.conf anyway (if, for example, a laptop has been moved onto a new network). I agree, however it would seem reasonable for something to sit between the applications and the bare resolver because: A/ It's the only thing that would need informed when the network setup changes, getting all the apps to monitor resolv.conf seems unlikely and unscalable. B/ Different processes are likely to be resolving the same things hostnames (e.g the same servers). C/ The standard resolver is very poor at handling unresponsive DNS servers, when the first goes offline or when say a laptop is unplugged from the network. From these nscd is the only option to get close to this just now ( "A" especially) and makes RHEL/Fedora usable on a corporate laptop (getting network manager to get resolv.conf to be reread by nscd and flush the hosts cache). There are plans for SSSD to eventually support the host map in nsswitch (https://fedorahosted.org/sssd/ticket/359) but it's not high on our priority list. Another alternative you might consider would be installing dnsmasq on these systems. |