Home / server / Questions / 342751
Accepted
Larry G. Wapnitsky
Asked: 2011-12-21 07:03:13 +0800 CST

LXC container templates?

  • 772

Is it possible to create an LXC container that you maintain only for the purpose of copying as a template? If so, how does one properly copy an LXC container?

lxc

3 Answers

  1. Best Answer

    Yes, an LXC container is some config files and a directory within the whole server. If you copy this directory and config files and adjust the parameters you can use it as a template. Just tar it and untar it to the new machine's directory.

    • 5

  2. This can be easily obtained using BTRFS filesystem in combination with snapshots.

    The template filesystem must reside in a subvolume on a btrfs filesystem, say

    btrfs subvolume create /mnt/btrfs/template

    After which you can populate it.

    To create the snapshot:

    btrfs subvolume snapshot /mnt/btrfs/template /mnt/btrfs/node-1

    Afterwards remove the snapshot with:

    btrfs subvolume delete delete /mnt/btrfs/node-1

    Advantages are that:

    • creation and removal is fast
    • no extra space is needed, only changed files (blocks) occupy extra space

    Further on, if you want to provide your container with some writable private directories on top of a read-only template filesystem you could use mount -o bind from within the container

     mount -o bind /mnt/btrfs/node-1/var /var
    • 1

  3. I also use a main template for all my containers.

    If you are using Ubuntu 14.04, lxc-clone is your friend to create new container based off a template.

    lxc-clone -o template_container -n new_container
    • 1