Launchpad Entry: foundations-karmic-golden-iso-image
Created: ColinWatson
Contributors: various
Packages affected: livecd-rootfs; new package
Summary
This work allows corporate IT users to:
- Create a customised image based on a tested configuration, consisting of packages they have approved. The user wants to create and distribute this image to employees to install on desktops and servers in their internal IT environment.
- Ensure that employees with access to sensitive information encrypt their data.
Release Note
We now offer a simple command-line tool to build customised Ubuntu installation images, suitable for use in corporate environments.
Rationale
Building customised images of Ubuntu is possible right now, but it involves a lot of reading and generally is complicated enough that many people who would like to do so see this as a barrier. We would like to lower this barrier.
User stories
- Sam is an IT manager responsible for deploying Ubuntu to employees' desktops. He has a list of applications he wants to include as standard, along with various small configuration changes. He would like a customised installation image that can be given to junior technicians to install on new desktop systems.
- Jane is an information security officer in the civil service. Some of her staff have access to confidential documents. She requires that documents stored on their laptops be encrypted, and instructs the IT manager preparing Ubuntu for deployment to ensure that their laptops are configured that way from installation.
Assumptions
- Corporate environments will not in general be satisfied with a simple live image with no provision for updates; they will generally want (or be highly receptive to arguments that they should want) a system that includes a local network-accessible archive, for the purpose of deploying updates.
- Small configuration changes will need to be possible without needing to rebuild packages (and thus merge security updates for the rest of time, etc.).
- If fetching the bulk of packages from the main Ubuntu archives is not possible, operators of this system will be able to set up a local mirror using any of the various tools we already offer for this purpose. (It may be that this should be simplified in various ways, but that is outside the scope of this specification.)
Design
We will offer a straightforward way to build a repository with any additional packages that are required (perhaps backports, PPA packages, packages otherwise not in the standard Ubuntu repositories for whatever reason, local builds, etc.). This will probably just wrap up existing technology.
There will be a special-purpose easy way to create a metapackage referring to all the top-level packages needed by the organisation.
Preseeding will be used to add the internal repository to /etc/apt/sources.list, to configure automatic upgrades, and optionally to configure home directory encryption (via ecryptfs).
We will advise that configuration changes should normally be made by changing packages (and will document the process for doing so), but in some cases it may instead be appropriate to permit manually editing configuration files in the live image.
Implementation
Existing software
The normal cdimage toolset we use to build official Ubuntu images is probably too complicated to set up here, but is by and large overkill for this purpose anyway. Most of the hard work it does involves building an apt archive on the CD, and with a customised image this is unnecessary.
livecd-rootfs, which we use to build official Ubuntu live filesystems, is reasonably straightforward to run on a user machine. It is currently fairly specific to Ubuntu and its known derivatives, so it needs to have some more customisation facilities added to it: in particular it needs to be able to take a custom package list on its command line.
There are several suitable packages for managing local repositories, and there is clearly no need to invent another; reprepro seems to be a likely candidate.
New software
To start with, we will offer a simple command-line toolset, using a single top-level command with subcommands. We expect that a graphical interface may be added later if time permits.
The initial command set will be similar to the following:
- init
- set up a configuration directory and a local repository
- add-distribution
add a distribution (e.g. karmic) to the archive
- remove-distribution
- remove a distribution from the archive
- add-package
add packages (.changes files) to the archive
- remove-package
- remove packages from the archive
- add-metapackage
- build a metapackage depending on a given list of packages, and add it to the archive
- configure-image
- create or edit configuration for an image
- build-image
- build a live CD image for a distribution
- edit-image
- unpack an image, chroot into it, let the operator edit it, and save the result as a new image
Test/Demo Plan
It's important that we are able to test new features, and demonstrate them to users. Use this section to describe a short plan that anybody can follow that demonstrates the feature is working. This can then be used during testing, and to show off after release. Please add an entry to http://testcases.qa.ubuntu.com/Coverage/NewFeatures for tracking test coverage.
This need not be added or completed until the specification is nearing beta.
Future work
It might make sense to rewrite livecd-rootfs in Python (it is currently written in shell) for better extensibility; or perhaps we should switch Ubuntu to live-helper. I think it is important that the software used for building customised images shares as much with the software used for building official Ubuntu images as possible, since that offers maximum probability of fixing common bugs in both rather than just in one.