Container enter failed

Problem

When you issue the following command you get an error:

[root@server ~]# vzctl enter 101
enter into CT 101 failed
Unable to open pty: No such file or directory

Solutions

Using strace

You can use strace to analyse the command further:

# strace -ff vzctl enter 101
....
fstat64(...st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0)...) fail
....

Recompile the kernel with the following option:

CONFIG_LEGACY_PTYS=y

LEGACY_PTYS

Temporary fix

Note: This is a temporary fix so you can enter the VE.

• Create the LEGACY_PTYS devices:

vzctl exec 101 /sbin/MAKEDEV tty
vzctl exec 101 /sbin/MAKEDEV pty
vzctl enter 101

Permanent fix with udev

• For a permanent fix with udev, you will need to force udev to make LEGACY_PTYS:

cat > /etc/udev/makedev.d/51-udev.nodes
# These device have to be created manually
tty0
tty1
tty2
tty3
....
ttyp0
ttyp1
ttyp2
ttyp3
....
ptyp0
ptyp1
ptyp2
ptyp3
....

Permanent fix without udev

• Alternatively, you can disable udev:

Edit the /etc/rc.d/rc.sysinit file and comment out the /sbin/start_udev line

Or you can run the following command:

sed -i 's|/sbin/start_udev|#/sbin/start_udev|g' /etc/rc.d/rc.sysinit

Warning Updates to the package which owns this file may revert your changes.

Note This was tested with CentOS VE.

Debian only

• Enter the VE manually

CTID=101
vzctl exec $CTID "mount -t devpts devpts /dev/pts" 
vzctl enter $CTID

• Remove udev using apt

CTID=101
vzctl exec $CTID apt-get remove udev
vzctl restart $CTID

See also

• OpenVZ Bug #130
• OpenVZ Bug #578