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4e3117ae50
The current LXC I/O controller looks for HUP to detect when a guest has quit. This isn't reliable as during initial bootup it is possible that 'init' will close the console and let mingetty re-open it. The shutdown of containers was also flakey because it only killed the libvirt I/O controller and expected container processes to gracefully follow. Change the I/O controller such that when it see HUP or an I/O error, it uses kill($PID, 0) to see if the process has really quit. Change the container shutdown sequence to use the virCgroupKillPainfully function to ensure every really goes away This change makes the use of the 'cpu', 'devices' and 'memory' cgroups controllers compulsory with LXC * docs/drvlxc.html.in: Document that certain cgroups controllers are now mandatory * src/lxc/lxc_controller.c: Check if PID is still alive before quitting on I/O error/HUP * src/lxc/lxc_driver.c: Use virCgroupKillPainfully
115 lines
3.3 KiB
HTML
115 lines
3.3 KiB
HTML
<html>
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<body>
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<h1>LXC container driver</h1>
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<p>
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The libvirt LXC driver manages "Linux Containers". Containers are sets of processes
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with private namespaces which can (but don't always) look like separate machines, but
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do not have their own OS. Here are two example configurations. The first is a very
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light-weight "application container" which does not have it's own root image. You would
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start it using
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</p>
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<h2>Cgroups Requirements</h2>
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<p>
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The libvirt LXC driver requires that certain cgroups controllers are
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mounted on the host OS. The minimum required controllers are 'cpuacct',
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'memory' and 'devices', while recommended extra controllers are
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'cpu', 'freezer' and 'blkio'. The /etc/cgconfig.conf & cgconfig
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init service used to mount cgroups at host boot time. To manually
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mount them use:
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</p>
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<pre>
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# mount -t cgroup cgroup /dev/cgroup -o cpuacct,memory,devices,cpu,freezer,blkio
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</pre>
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<p>
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NB, the blkio controller in some kernels will not allow creation of nested
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sub-directories which will prevent correct operation of the libvirt LXC
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driver. On such kernels, it may be neccessary to unmount the blkio controller.
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</p>
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<h3>Example config version 1</h3>
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<p></p>
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<pre>
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<domain type='lxc'>
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<name>vm1</name>
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<memory>500000</memory>
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<os>
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<type>exe</type>
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<init>/bin/sh</init>
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</os>
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<vcpu>1</vcpu>
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<clock offset='utc'/>
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<on_poweroff>destroy</on_poweroff>
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<on_reboot>restart</on_reboot>
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<on_crash>destroy</on_crash>
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<devices>
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<emulator>/usr/libexec/libvirt_lxc</emulator>
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<interface type='network'>
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<source network='default'/>
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</interface>
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<console type='pty' />
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</devices>
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</domain>
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</pre>
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<p>
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In the <emulator> element, be sure you specify the correct path
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to libvirt_lxc, if it does not live in /usr/libexec on your system.
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</p>
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<p>
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The next example assumes there is a private root filesystem
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(perhaps hand-crafted using busybox, or installed from media,
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debootstrap, whatever) under /opt/vm-1-root:
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</p>
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<p></p>
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<pre>
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<domain type='lxc'>
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<name>vm1</name>
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<memory>32768</memory>
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<os>
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<type>exe</type>
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<init>/init</init>
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</os>
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<vcpu>1</vcpu>
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<clock offset='utc'/>
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<on_poweroff>destroy</on_poweroff>
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<on_reboot>restart</on_reboot>
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<on_crash>destroy</on_crash>
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<devices>
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<emulator>/usr/libexec/libvirt_lxc</emulator>
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<filesystem type='mount'>
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<source dir='/opt/vm-1-root'/>
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<target dir='/'/>
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</filesystem>
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<interface type='network'>
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<source network='default'/>
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</interface>
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<console type='pty' />
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</devices>
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</domain>
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</pre>
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<p>
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In both cases, you can define and start a container using:</p>
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<pre>
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virsh --connect lxc:/// define v1.xml
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virsh --connect lxc:/// start vm1
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</pre>
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and then get a console using:
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<pre>
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virsh --connect lxc:/// console vm1
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</pre>
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<p>Now doing 'ps -ef' will only show processes in the container, for
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instance. You can undefine it using
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</p>
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<pre>
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virsh --connect lxc:/// undefine vm1
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</pre>
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</body>
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</html>
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