Diff for "Running/LXC"

Not logged in - Log In / Register

Differences between revisions 66 and 67
Revision 66 as of 2011-12-14 20:51:27
Size: 6821
Editor: gary
Comment:
Revision 67 as of 2011-12-16 15:42:26
Size: 7526
Editor: gary
Comment:
Deletions are marked like this. Additions are marked like this.
Line 142: Line 142:
== lxc-start fails, complaining that there is "No such device" of "virbr0" ==

Short answer: do you have dnsmasq installed? If so, uninstall it, or turn it off ('''{{{/etc/init.d/dnsmasq stop}}}'''). Then use '''{{{sudo virsh net-start default}}}''' and then retry. [[http://mytipsandtricson.blogspot.com/2010/12/kvm-failed-to-start-network-default-in.html|(Source)]]

Slightly more details: Normally, if you look at the "ifconfig" output, you will see a virbr0 interface. If it is not there, you'll have problems. In that case, you'll probably also see that the virtual network is inactive (see the output of '''{{{virsh net-list --all}}}'''). Apparently dnsmasq fights all this (and wins).

This page explains how to set up and run Launchpad (for development) inside a LXC.

Why?

Launchpad development setup makes significant changes to your machine; its nice to be unaffected by those except when you are actually doing such development.

Also, launchpad has some limitations on concurrent testing per-machine and so forth - multiple container's can be used to work around this.

Make a LXC

  1. Install lxc
    sudo apt-get install lxc libvirt-bin
  2. Create a config for your containers
    sudo dd of=/etc/lxc/local.conf << EOF
    lxc.network.type=veth
    lxc.network.link=virbr0
    lxc.network.flags=up
    EOF
  3. Create a container
    sudo lxc-create -t ubuntu -n lucid-test-lp -f /etc/lxc/local.conf -- -r lucid -a i386 -b robertc
    • If you want a proxy:
      sudo http_proxy=http://host:port/ lxc-create -t ubuntu -n lucid-test-lp -f /etc/lxc/local.conf -- -r lucid -a i386 -b robertc
    • And if you want to set a custom mirror, similar to http_proxy, but set MIRROR= instead.
  4. Start the container
    sudo lxc-start -n lucid-test-lp
    • Ignore the warning about openssh crashing - it restarts on a later event.
  5. You can log in as root (password "root"), or as your user, but without sudo powers (then use "su root" with password "root" to become root).
  6. Grab the ip address (handed out via libvirt's dhcp server) - you may wish to ssh in rather than using the console (seems to have better termcap experience).
    ip addr show dev eth0 | grep 'inet'
    • Alternatively, if you add '192.168.122.1' (libvirt's dnmasq default address) to your /etc/resolv.conf you can use:
    ssh <container-name>. 
    • [XXX Another alternative may be to use avahi. This should be tested and documented. The advantage would be that you do not have to keep track of your vm's ipin resolv.conf as you change networks.]
  7. The new container won't have your proxy / mirror settings preserved. Customise it at this point before going further if you care about this.
  8. Enable multiverse (rocketfuel-setup wants it, don't ask me why). See the "Updating" section below for more details on this.
  9. Install some additional packages we'll need to run rocketfuel-setup etc.
    apt-get install bzr
    # if you have a localised (non-C) locale:
    # not doing this will cause postgresql to fail to install, with -hilarious- results as database-developer-setup will think you have 8.2 installed.
    # You can tell if you need this if the prior apt commands spewed locale warnings.
    # Pick your specific language pack.
    apt-get install language-pack-en
  10. Inside the container grant the user sudo rights:
    adduser $username sudo
  11. And add their user group:
     addgroup --gid NNN $username
    where NNN is as reported by
     groups $username
  12. To stop it now run 'poweroff -n' in the lxc instance and then 'sudo lxc-stop -n lucid-test-lp' in the host.
  13. Start it up again - headless now, we have the ip address from before.
    sudo lxc-start -n lucid-test-lp -d
  14. ssh <vm IP address> to connect to the VM. Your ssh key is already present because of the bind mount to your home dir.

  15. You can now follow the getting-started on LP instructions. Be warned that changes in ~ will affect you outside the container. You will want to run rocketfuel-setup with --no-workspace if your home already has a workarea. You may need to run utilities/launchpad-database-setup separately too.

  16. You probably want to follow Running/RemoteAccess has a discussion for how you can configure things so your non-container browser can access web pages from within the container.

  17. rabbitmq may fail to start up. If that happens it appears to be a mnesia glitch best sorted by zapping mnesia.

    sudo rm -rf /var/lib/rabbitmq/mnesia/rabbit/*
    sudo service rabbit-mq start

Updating

Updating deb packages in an LXC has a few issues as of this writing.

  1. To get started, you'll need to add the apt sources. Here's an example /etc/apt/sources.list.
    deb http://archive.ubuntu.com/ubuntu lucid main universe
    deb-src http://archive.ubuntu.com/ubuntu lucid main universe
    deb http://archive.ubuntu.com/ubuntu lucid-updates main universe
    deb-src http://archive.ubuntu.com/ubuntu lucid-updates main universe
    deb http://archive.ubuntu.com/ubuntu lucid main multiverse
    deb-src http://archive.ubuntu.com/ubuntu lucid main multiverse
    deb http://archive.ubuntu.com/ubuntu lucid-updates main multiverse
    deb-src http://archive.ubuntu.com/ubuntu lucid-updates main multiverse
  2. Bug 902190 describes the first problem when you will try to update. To work around this, at the bottom of "/var/lib/lxc/server/config" (e.g. /var/lib/lxc/lucid-test-lp/config) add this snippet:

    # Mods to allow udev upgrade
    lxc.cgroup.devices.allow = c 108:0 rwm
    lxc.cgroup.devices.allow = b 7:0 rwm
    lxc.cgroup.devices.allow = c 10:200 rwm
  3. Bug 892892 describes the next problem you will encounter. Serge Hallyn reports that Stephane Graber has fixed this in Precise, and they will SRU it into Oneiric. [He suggests that for a quick fix, we can just turn off the devices cgroup - edit the container's config and comment out all 'lxc.cgroup.devices =' lines, but gary was unable to get this to work.] A quick workaround is to specify that you don't want to upgrade this package. I did it somehow with an aptitude gyration; documented approaches welcome.

Problems

lxc-create fails with errors that it is unable to access archive.ubuntu.com

Gary encountered this problem when trying to contain a second lxc container. After trying more careful approaches, Serge Hallyn recommended that we just wipe out the lxc cache. "rm -rf /var/cache/lxc/*". This solved the problem. He went on to say that he wondered if we ought to automatically purge the cache every week or so, so the cache does seem potentially problematic.

database-developer-setup fails, and thinks you are on Postgres 8.2

As noted above, if you have a localised (non-C) locale, you ned to install your specific language pack. For instance, if your computer has a localised English locale, use this:

apt-get install language-pack-en

lxc-start fails, complaining that there is "No such device" of "virbr0"

Short answer: do you have dnsmasq installed? If so, uninstall it, or turn it off (/etc/init.d/dnsmasq stop). Then use sudo virsh net-start default and then retry. (Source)

Slightly more details: Normally, if you look at the "ifconfig" output, you will see a virbr0 interface. If it is not there, you'll have problems. In that case, you'll probably also see that the virtual network is inactive (see the output of virsh net-list --all). Apparently dnsmasq fights all this (and wins).

Other problems

If other lxc users don't have an idea (known lxc users as of this writing include lifeless, wgrant, frankban and gary_poster) try asking hallyn or Spamaps on #ubuntu-server on freenode.

References

Alternatively

You can also run in a chroot environment or a VM.

Running/LXC (last edited 2017-09-22 08:30:24 by cjwatson)