Configure

You have at least one lxc image already downloaded which you can find in your local lxc image store

lxc image list

If not, you can import an ubuntu image on the local image repo with the following command:

lxc image copy ubuntu:16.04 local:

And take note of the fingerprint you need for the next steps.

The config file should look like:

connect:
  url:                        < The URL with port where to reach lxd engine >               # Mandatory
  trust-password:             < The trust password you have set for the lxd environment >                    # Mandatory

create-container:
  container-name:               < The name of the container which will be created >                                 # default: "image-generator"
  container-image-fingerprint:  < The fingeprint of the image which will be used as base image for the container >  # Mandatory; you do not need the complete image fingerprint, the one shown by lxc image list is enough

copy-files:
  file-tarball: < Path to the tar archive containing all scripts you want to push on the image >  # default: "./etc/files.tar"
  file-dest:  < Path where to copy the content of the tar archive on the container >              # default /root/files.tar

execute-script:
  script: < Which script to be executed >                                                       # Mandatory
  clean-tmp-files: < remove the temporary files used for copying the tarball on the container>  # default: False
  # lxc always assumes you are in /root, thus take care if you use relative paths to the scripts here

create-image:
  destination: < Path of the folder where the image will be saved >         # default: "/tmp"
  alias: <additional alias to give to the created image>                    # default: "Published by image-generator"
  name: <name of the result image>                                          # generated-image
# if the destination does not yet contain the ending tar.gz it will be added automatically

clean:
  container: < remove the container used for creating the lxc image>                        # default: True
  image-store: < remove the image created from the container from your local image store>   # default: True

# You can (re)import the images anytime by lxc image import < Your path to the desired image.tar.gz > --alias < Your Alias here >

Run

NOTE if you get this error while running image generator:

Traceback (most recent call last):
  File "/usr/bin/pip3", line 11, in <module>
    sys.exit(main())
  File "/usr/lib/python3/dist-packages/pip/__init__.py", line 215, in main
    locale.setlocale(locale.LC_ALL, '')
  File "/usr/lib/python3.5/locale.py", line 594, in setlocale
    return _setlocale(category, locale)
locale.Error: unsupported locale setting

then as a quick fix, you can run:

export LC_ALL=C

Check the help

image-generator --help
usage: image-generator [-h] [-f FILE] [-d] [-action ACTION] [-params PARAMS]
                       [-dry]

optional arguments:
  -h, --help            show this help message and exit
  -f FILE, --file FILE  the file scenario with the action to execute
  -d, --debug           show debug prints
  -action ACTION        The action to execute
  -params PARAMS        The parameters to the action
  -dry                  Run dryrun

and then run it with sudo:

sudo image-generator -f <PATH-TO-THE-CONFIGURATION-FILE>

sudo rights are needed only because it is required by the process of extracting the image downloaded from lxd.

Test it

for testing it is possible to do a dry run by running:

sudo image-generator -f <PATH-TO-THE-CONFIGURATION-FILE> -dry --debug

it will execute every step but the installation script and finally will also delete the downloaded image.