LXC Builder

Type: lxc

The lxc Packer builder builds containers for lxc1. The builder starts an LXC container, runs provisioners within this container, then exports the container as a tar.gz of the root file system.

The LXC builder requires a modern linux kernel and the lxc or lxc1 package. This builder does not work with LXD.

Note: to build Centos images on a Debian family host, you will need the yum package installed.
Some provisioners such as ansible-local get confused when running in a container of a different family. E.G. it will attempt to use apt-get to install packages, when running in a Centos container if the parent OS is Debian based.

Basic Example

Below is a fully functioning example.

{
  "builders": [
    {
      "type": "lxc",
      "name": "lxc-trusty",
      "config_file": "/tmp/lxc/config",
      "template_name": "ubuntu",
      "template_environment_vars": ["SUITE=trusty"]
    },
    {
      "type": "lxc",
      "name": "lxc-xenial",
      "config_file": "/tmp/lxc/config",
      "template_name": "ubuntu",
      "template_environment_vars": ["SUITE=xenial"]
    },
    {
      "type": "lxc",
      "name": "lxc-jessie",
      "config_file": "/tmp/lxc/config",
      "template_name": "debian",
      "template_environment_vars": ["SUITE=jessie"]
    },
    {
      "type": "lxc",
      "name": "lxc-centos-7-x64",
      "config_file": "/tmp/lxc/config",
      "template_name": "centos",
      "template_parameters": ["-R", "7", "-a", "x86_64"]
    }
  ]
}

Configuration Reference

Required:

config_file (string) - The path to the lxc configuration file.
template_name (string) - The LXC template name to use.
template_environment_vars (array of strings) - Environmental variables to use to build the template with.

Optional:

target_runlevel (number) - The minimum run level to wait for the container to reach. Note some distributions (Ubuntu) simulate run levels and may report 5 rather than 3.
output_directory (string) - The directory in which to save the exported tar.gz. Defaults to output-<BuildName> in the current directory.
container_name (string) - The name of the LXC container. Usually stored in /var/lib/lxc/containers/<container_name>. Defaults to packer-<BuildName>.
command_wrapper (string) - Allows you to specify a wrapper command, such as ssh so you can execute packer builds on a remote host. Defaults to Empty.
init_timeout (string) - The timeout in seconds to wait for the the container to start. Defaults to 20 seconds.
template_parameters (array of strings) - Options to pass to the given lxc-template command, usually located in /usr/share/lxc/templates/lxc-<template_name>. Note: This gets passed as ARGV to the template command. Ensure you have an array of strings, as a single string with spaces probably won't work. Defaults to [].
create_options (array of strings) - Options to pass to lxc-create. For instance, you can specify a custom LXC container configuration file with ["-f", "/path/to/lxc.conf"]. Defaults to []. See man 1 lxc-create for available options.
start_options (array of strings) - Options to pass to lxc-start. For instance, you can override parameters from the LXC container configuration file via ["--define", "KEY=VALUE"]. Defaults to []. See man 1 lxc-start for available options.
attach_options (array of strings) - Options to pass to lxc-attach. For instance, you can prevent the container from inheriting the host machine's environment by specifying ["--clear-env"]. Defaults to []. See man 1 lxc-attach for available options.