LXC is a tool to create and manage containers. It contains a full featured container with the isolation / virtualization of the pids, the ipc, the utsname, the mount points, /proc, /sys, the network and it takes into account the control groups. It is very light, flexible, and provides a set of tools around the container like the monitoring with asynchronous events notification, or the freeze of the container. This package is useful to create Virtual Private Server, or to run isolated applications like bash or sshd.

Resources

• LXC Project homepage
• LXC 1.0 blog post series - must read to get quick overview what's out there
• Linux Containers mailing list
• Gentoo wiki about LXC
• Funtoo LXC pages
• Arch Linux documentation
• OpenSUSE documentation
• Ubuntu Server Guide
• Alpine Linux Docs
• libvirt LXC driver
• Systemd Container Interface

• 3.8+ kernel according to docker devs
• lxc package
• cgroups mounted, use systemd or libcgroup for that.

Build the guest container.

# lxc-create -n test
lxc-create: No config file specified, using the default config /etc/lxc/default.conf
'test' created
 
# lxc-ls --fancy 
NAME   STATE    IPV4           IPV6  
-----------------------------------
test   STOPPED  -          

this just creates $LXC_ROOT/test directory with config copied from /etc/lxc/default.conf inside.

create guest with default config using pld template:

# lxc-create -n test -t pld

NOTYET:

There are two versions of PLD available for guest systems:

• ac - PLD 2.0 (Ac)
• th - PLD 3.0 (Th)

You may choose one using -R option:

# lxc-create -t pld-test -p pld -f network-configuration-file -- -R th

!!! WARNING: pld template for LXC is yet to be written !!!

Currently lxc-stop -n test sends SIGPWR to init inside container, but rc-scripts fails to shutdown things properly (shutdown scripts are not invoked). For workaround, stop services manually before issueing lxc-stop or run poweroff/halt/reboot from container.

Details: In process table is only this process runrning, no further actions from rc-scripts:

/sbin/shutdown -f -h +2 Power Failure; System Shutting Down

having audit_control dropped:

config

lxc.cap.drop = audit_control

pam_loginuid.so does not allow sshd to login:

Nov 24 16:02:10 test sshd[2694]: error: PAM: pam_open_session(): Cannot make/remove an entry for the specified session

You can either workaround to disable pam_loginuid.so in the authentication rules:

# sed '/pam_loginuid.so/s/^/#/g' -i  /etc/pam.d/*

Or just do not drop the capability.

syslog-ng gives following on startup:

# service syslog-ng restart
syslog-ng: Error setting capabilities, capability management disabled; error='Operation not permitted'
Stopping syslog-ng service.............................................................[ DONE ]
Starting syslog-ng service.............................................................[ DONE ]

: no solution yet

When in Vserver, guest processes are not visible in host, then in LXC all guest processes are visible. Beware when running killall(1) commands on host.

Also, unfortunately /proc/PID/root points to / for LXC guests as well, so rc-scripts filter_chroot() can't differentiate between host and guest processes.

Also, dmesg(1) in guest sees hosts' dmesg by default, you can turn this off by setting kernel.dmesg_restrict=1 sysctl param, available since 2.6.37 kernel.

Commands:

static networking, set VSERVER=yes and VSERVER_ISOLATION_NET=yes in guest /etc/sysconfig/system to disable all network configuration by guest.

1. uses macvlan
2. that interface is NOT visible on host
3. you can't filter it from host's firewall
4. you HAVE to set mac. If not - on every container start you'll have different one (your router will not pass the traffic).
5. iptables is initialized from lxc.hook.pre-mount hook (ran in the container's namespace and having macvlan interface visible)

first boot with hwaddr line disabled, look what the random address was assigned, set it in config.

also you may use some generation techniques like these: using last three ip numbers and Xen's OUI (00:16:3e) address space. If IP is 192.168.2.160, then:

$ printf "00:16:3e:%x:%x:%x" 168 2 160
00:16:3e:a8:2:a0

lxc.network.type = macvlan
lxc.network.flags = up
#lxc.network.hwaddr = 00:16:c0:a8:3:34
lxc.network.link = eth0
lxc.network.macvlan.mode = bridge
lxc.network.name = eth0
lxc.network.ipv4 = 192.168.2.160/23
lxc.network.ipv4.gateway = 192.168.2.1
 
lxc.hook.pre-mount = /sbin/service iptables start
lxc.cap.drop       = net_admin

# lxc for test
 
lxc.network.type = macvlan
lxc.network.flags = up
#lxc.network.hwaddr = 00:16:c0:a8:3:34
lxc.network.link = eth0
lxc.network.macvlan.mode = bridge
lxc.network.name = eth0
lxc.network.ipv4 = 192.168.2.160/23
lxc.network.ipv4.gateway = 192.168.2.1
 
lxc.rootfs = /srv/test
lxc.utsname = pldmachine.local
lxc.tty = 4
lxc.pts = 1024
 
# load iptables, if you want to setup firewall when container is already up
# you should  run 'lxc-attach -e -n test -- service iptables start'
lxc.hook.pre-mount = /sbin/service iptables start
 
# lxc.mount.entry is prefered, because it supports relative paths
lxc.mount = /var/lib/lxc/test/fstab
 
lxc.cap.drop                            = linux_immutable
#lxc.cap.drop                            = sys_boot # works as expected in newer kernels (3.4+)
lxc.cap.drop                            = syslog
 
# don't drop net_admin, allows firewall to be configured from inside
lxc.cap.drop                            = net_admin
 
# http://www.funtoo.org/Linux_Containers
## Capabilities, see capabilities(7) what is available
#lxc.cap.drop                            = audit_control
lxc.cap.drop                            = audit_write
lxc.cap.drop                            = mac_admin
lxc.cap.drop                            = mac_override
lxc.cap.drop                            = mknod
lxc.cap.drop                            = setfcap
lxc.cap.drop                            = setpcap
lxc.cap.drop                            = sys_admin
#lxc.cap.drop                            = sys_boot
#lxc.cap.drop                            = sys_chroot # required by SSH
lxc.cap.drop                            = sys_module
#lxc.cap.drop                            = sys_nice
lxc.cap.drop                            = sys_pacct
lxc.cap.drop                            = sys_rawio
lxc.cap.drop                            = sys_resource
lxc.cap.drop                            = sys_time
#lxc.cap.drop                            = sys_tty_config # required by getty
 
lxc.autodev = 0
 
# When using LXC with apparmor, uncomment the next line to run unconfined:
lxc.aa_profile = unconfined
 
# cgroups
# Devices
lxc.cgroup.devices.deny = a # Deny access to all devices
 
# /dev/null and zero
lxc.cgroup.devices.allow = c 1:3 rwm
lxc.cgroup.devices.allow = c 1:5 rwm
# consoles
lxc.cgroup.devices.allow = c 5:1 rwm
lxc.cgroup.devices.allow = c 5:0 rwm
lxc.cgroup.devices.allow = c 4:0 rwm
lxc.cgroup.devices.allow = c 4:1 rwm
# /dev/{,u}random
lxc.cgroup.devices.allow = c 1:9 rwm
lxc.cgroup.devices.allow = c 1:8 rwm
lxc.cgroup.devices.allow = c 136:* rwm
lxc.cgroup.devices.allow = c 5:2 rwm
# rtc
lxc.cgroup.devices.allow = c 254:0 rm