This are notes for my LXC workshop, in state of flux

Cgroups

• http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt
• http://www.webupd8.org/2010/11/alternative-to-200-lines-kernel-patch.html
• http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/ch01.html

• Resource allocation using cgroups http://blip.tv/file/4773168

Systemd

• systemd, beyond init http://www.youtube.com/watch?v=TyMLi8QF6sw

launchd alterntive, somilar to inetd, but for unix sockets (mostly)

LXC

Virtual Servers and Checkpoint/Restart in Mainstream Linux http://lxc.sourceforge.net/doc/sigops/appcr.pdf

• you don't have hardware virtualization (netbooks, anyone?)
• http://lxc.teegra.net/
• http://en.gentoo-wiki.com/wiki/LXC
• http://sysadvent.blogspot.com/2010/12/day-1-linux-containers-lxc.html
• Amazon EC2
• http://www.phenona.com/blog/using-lxc-linux-containers-in-amazon-ec2/
• Running X
• http://blog.ikibiki.org/2011/04/05/Running_X_from_LXC/
• LVM integration
• http://s3hh.wordpress.com/2011/03/30/one-more-lxc-clone-update/

Virtual, virtual...

• PCI network cards http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization/sect-Para-virtualized_Windows_Drivers_Guide-How_SR_IOV_Libvirt_Works.html

don't delete files

dpkg-divert --rename /etc/init/theinitfile.conf

network

prepare host machine

br0
dnsmasq

1. sysctl -w net.ipv4.ip_forward=1

1. iptables -t nat -A POSTROUTING -o wlan0 -j SNAT --to-source=WLAN0_IP

or

1. iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE

macvlan

• aliased IP at eth devel
• new device with own mac with offloading
• can't communicate with other containers or host (< 2.6.33)

lxc.network.type=macvlan
lxc.network.link=eth0
lxc.network.flags=up

ip link add link <phys> name <vif> address <mac address> type macvlan mode (bridge|vepa|private)

ip link add link bond200 name bond200:0 address 00:aa:bb:cc:dd:ee type macvlan mode bridge

ip -d show link bond200:0

lxc.network.type = macvlan
lxc.network.macvlan.mode = bridge
lxc.network.flags = up
lxc.network.link = bond200
lxc.network.name = eth7
lxc.network.mtu = 1500
lxc.network.ipv4 = 192.168.90.11/24
lxc.network.hwaddr = 4a:49:43:49:79:0B

veth

lxc.network.type=veth
lxc.network.link=br0
lxc.network.flags=up

phys

kernel > 2.6.35

lxc.network.type=phys
lxc.network.link=eth1
lxc.network.name=eth1

limit container resources

cpuset.cpus

echo 1 > /cgroup/<name>/cpuset.cpus # 2nd CPU!

echo 1,2,3 > /cgroup/<name>/cpuset.cpus

echo 0-7 > /cgroup/<name>/cpuset.cpus

lxc-execute -n foo -s lxc.cgroup.cpuset.cpus="1,2,3" myforks

cpu.shares

lxc-execute -n foo -s lxc.cgroup.cpu.shares=1 /bin/bash

lxc-execute -n bar -s /bin/bash

while $(true); do echo -n . ; done

lxc-cgroup -n foo cpu.shares=1024

memory

lxc.cgroup.memory.limit_in_bytes = 256M
lxc.cgroup.memory.memsw.limit_in_bytes = 1G

disk

LVM?
quota (it can be bypassed if the container runs with CAP_SYS_ADMIN and/or CAP_SYS_RESOURCE capabilities)

LXC commands

lxc-create

/usr/lib/lxc/templates/

export MIRROR=http://192.168.1.20:3142/ftp.debian.org
export SUITE=lenny

cat > /tmp/lenny.conf
lxc.network.type=veth
lxc.network.link=br0
lxc.network.flags=up

1. <ctrl+d>

t61p:~# lxc-create -n lenny -t debian -f /tmp/lenny.conf

lxc-execute

application container (shares filesystem!)

lxc-ssh

lxc-execute -n foo -s lxc.utsname=foo /bin/bash
lxc-execute -n bar -s lxc.utsname=bar /bin/bash

lxc-attach

Needs kernel patch

lxc-attach n n0 - /usr/sbin/tcpdump -i eth0

devices

http://lwn.net/Articles/273208/

lxc.cgroup.devices.allow = <type> <major>:<minor> <perm>

<type> : b (block), c (char), etc ...
<major> : major number
<minor> : minor number (wildcard is accepted)
<perms> : r (read), w (write), m (mapping)

monitoring

htop

htop - cgroups > r192

t61p:/tmp# apt-get source htop
t61p:/tmp# apt-get build-dep htop
t61p:/tmp# dpkg-source -x htop_0.9-2.dsc
t61p:/tmp# cd htop-0.9/

t61p:/tmp/htop-0.9# DEB_BUILD_OPTIONS="--enable-cgroup" fakeroot debian/rules binary

1. sigh, no work, patch debian/rules to add --enable-cgroup

t61p:/tmp/htop-0.9# fakeroot debian/rules binary
t61p:/tmp/htop-0.9# dpkg -i ../htop_0.9-2_i386.deb

procfs

http://lxc.sourceforge.net/download/procfs/procfs.tar.gz (fuse, defunct)
http://www.tinola.com/lxc/ (somewhat newer)

debugging

lxc-start --logpriority=TRACE -o /tmp/trace.log --name my_container

(must have redirect to file!)

slow network?

/usr/sbin/ethtool -K br0 sg off
/usr/sbin/ethtool -K br0 tso off

kernel patches

http://lxc.sourceforge.net/patches/linux/

Are we in container?

on host:

dpavlin@stage:~$ cat /proc/$$/cgroup
1:net_cls,freezer,devices,cpuacct,cpu,ns,cpuset:/

inside container:

dpavlin@narada:~$ cat /proc/$$/cgroup
1:net_cls,freezer,devices,cpuacct,cpu,ns,cpuset:/narada

32-bit guest on 64-bit kernel

(lxc >= 0.7.3)

lxc.arch=x86

Container tweaks

udev

echo udev hold | dpkg --set-selections

nfs

kernel doesn't have nfs namespaces yet, use user-space nfs servers:

• http://unfs3.sourceforge.net
• http://sourceforge.net/apps/trac/nfs-ganesha

chromium

• http://www.chromium.org/chromium-os/chromiumos-design-docs/system-hardening
• http://git.chromium.org/gitweb/?p=chromiumos/platform/minijail.git;a=summary

pam

• http://pam-netns.sourceforge.net/

pam_netns allows to setup a private network namespace for every user
session (comparable with pam_namespace for filesystem namespaces). This
is especially useful on multiseat environments.