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Old 06-26-2008, 08:38 PM   #1
quinthar
LQ Newbie
 
Registered: Sep 2004
Posts: 11

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chroot temporarily "cannot find name for group ID 0"


I have lighttpd installed in a chroot created with debootstrap and it works great. However, if I leave the server alone for a long time and then come back, I get the strangest error when I try to chroot into the... chroot:

Code:
[root@XXXX svn]# chroot staging/www
id: cannot find name for group ID 0
id: cannot find name for group ID 1
id: cannot find name for group ID 2
id: cannot find name for group ID 3
id: cannot find name for group ID 4
id: cannot find name for group ID 6
id: cannot find name for group ID 10
I have no name!@XXXX:/#
Basically, it behaves exactly like /etc/group is missing. However, if I do absolutely nothing for about five minutes -- modify no files nor permissions -- and then re-chroot in, it works just fine. For example, here's me exiting a broken chroot and then immediately chrooting back into it and it works fine:

Code:
I have no name!@XXXX:/etc# exit
[root@XXXX svn]# chroot staging/www
root@XXXX:/#
I'm at a loss to explain it. Once it's working it seems to keep working for as long as I'm active; I haven't nailed down how long it takes to break again but it seems to be about a day. During this period lighttpd and all the processes in the chroot seem to work just fine, thankfully (but I need to confirm this).

It seems like something is maybe getting cached by bash and times out after a few minutes? Can you offer any explanation of this behavior, and ideally a correction? Thanks!

-david

PS: The system hosting the chroot is Fedora Core 4. I have the same chroot on an Ubuntu system and it doesn't seem to have this problem. My goal is to upgrade the FC4 system to Debian, but I don't have physical access so it's a bit of a dicey task.

PPS: Once working, the chroot continues to work even if I log out and SSH back into the FC4 box: when chrooting in with the new SSH session it works on first try, so long as I re-log in within a day or so. So it's not anything in the host SSH session, apparently.

Last edited by quinthar; 06-26-2008 at 08:47 PM. Reason: Updated for PPS
 
Old 06-28-2008, 07:58 PM   #2
quinthar
LQ Newbie
 
Registered: Sep 2004
Posts: 11

Original Poster
Rep: Reputation: 0
So I've been testing periodically and I can chroot into it fine for several days, until suddenly it stopped working -- exactly like before. I'm not sure if it stopped working due to some timeout or due to me doing something; I'll need to keep looking into that.

However, I noticed something new: I created a new chroot in the same directory as the old one (the first was named "www" to hold a webserver, and the new one is named "db" to hold a database). Both chroots are made with debootstrap. I can log into the "db" chroot just fine, but not the "www" one:

Code:
[root@XXXX staging]# chroot db 
root@XXXX:/# exit      
[root@XXXX staging]# chroot www
id: cannot find name for group ID 0
id: cannot find name for group ID 1
id: cannot find name for group ID 2
id: cannot find name for group ID 3
id: cannot find name for group ID 4
id: cannot find name for group ID 6
id: cannot find name for group ID 10
I have no name!@XXXX:/# exit
[root@XXXX staging]#
So I'm running out of ideas of what could be causing this. I don't think it's anything inside the chroot (because they're both the same and one works, not to mention both work if I just wait long enough). But it doesn't seem to be anything in the session either (because I can chroot into one fine, back out, and then fail chrooting into the other -- with the same SSH session). So... any ideas?

As for the www chroot, as predicted, it eventually came back:

Code:
[root@XXXX staging]# chroot www
root@XXXX:/# exit
[root@XXXX staging]#
The real world consequence of this is I'm stuck with at least 5 minutes of downtime when I need to restart the chroot services, and I'm not sure if any internal functionality (such as email sending) breaks during this mystery period when the chroot is in a semi-zombie state.

Uck. I'd love any suggestions you have.

-david
 
  


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