Hi all, I'd like to report a few problems/gotchas I ran into while testing LXC in Fedora 13 (current Rawhide). 1. PTY allocation fails (PEBKAC/documentation issue) While starting up a guest (CentOS 5.4) I get a series of messages: lxc-start 1268746923.067 WARN lxc_conf - failed to mount '/dev/pts/2'->'./rootfs.centos/dev/tty1' lxc-start 1268746923.067 WARN lxc_conf - failed to mount '/dev/pts/3'->'./rootfs.centos/dev/tty2' lxc-start 1268746923.067 WARN lxc_conf - failed to mount '/dev/pts/4'->'./rootfs.centos/dev/tty3' lxc-start 1268746923.067 WARN lxc_conf - failed to mount '/dev/pts/5'->'./rootfs.centos/dev/tty4' lxc-start 1268746923.067 INFO lxc_conf - 4 tty(s) has been setup The mingetty set up to start at /dev/tty1 is not attached to any known TTY and is not accessible via lxc-console: CONTAINER PID TTY TIME CMD centos 1186 ? 00:00:00 init centos 1368 ? 00:00:00 syslogd centos 1371 ? 00:00:00 klogd centos 1386 ? 00:00:00 sshd centos 1396 ? 00:00:00 mingetty The mount fails because there are no ttyX files inside the container's file system. This may qualify as a PEBKAC but it might be nice to document somewhere (touching empty plain files with appropriate names makes the container boot). 2. Weird strace behaviour across pidns boundary When strace'ing (with -ff) lxc-start, I get a proper strace for the directly spawned process and the container init. However, any processes spawned by the container's init are not straced properly (I get two empty files, named <foo>.<pid-in-root-ns> and <foo>.2 -- presumably pid inside the container). The container also seems to malfunction under strace (looks like exec() failing as lxc-ps shows two "init" processes). This is quite painful as it prevents strace'ing processes in containers even after startup. Here's a snippet of strace'ing a bash (pid 179 inside, pid 2959 outside) trying to run 'ls'. The shell hangs until I kill the strace process. pipe([3, 4]) = 0 clone(Process 197 attached child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb7859708) = 197 Process 2999 attached (waiting for parent) [pid 2959] setpgid(197, 197) = 0 [pid 2959] rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 [pid 2959] rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0 [pid 2959] close(3) = 0 [pid 2959] close(4) = 0 [pid 2959] rt_sigprocmask(SIG_BLOCK, [CHLD TSTP TTIN TTOU], [CHLD], 8) = 0 [pid 2959] ioctl(255, TIOCSPGRP, [197]) = 0 [pid 2959] rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0 [pid 2959] rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 [pid 2959] rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0 [pid 2959] waitpid(-1, Process 2959 suspended ^C <unfinished ...> Process 2959 detached Process 197 detached Process 2999 detached 'strace ls' ran completely inside the container works as expected. 3. Missing /dev/console There's no "obviously good" default (apart maybe from lxc-start's stdout/err) but I guess the messages from init could end up somewhere useful (right now it tries /dev/console, /dev/tty0 and /dev/null, in order). Maybe an extra PTY (just start counting from 0) would be enough? Or even a symlink (tty0 -> tty1). But then I think that lxc-start should attach to the PTY as early as possible to capture boot messages. Best regards, Grzegorz Nosek _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
