Roadmap

(past) Tails 0.13 has the harmless part of the feature/incremental-upgrades branch merged (users creation with sudo credentials, dependencies installation), leaving aside the part about running the upgrade frontend automatically at startup. => Tails 0.13 should have been able to incrementally upgrade to something newer, when running the upgrade frontend by hand, but the included Tails OpenPGP signing key expired too quickly for this to happen.
(past) Now that 0.14 is out:
- Prepare IUK: done
- Update upgrade-description files: done
- Ask beta testers to try the incremental upgrade process: done
- Find most critical bugs: done.
(pending review) Complete phase one: make ready for more alpha testing

See phase one.
(pending review) Complete phase two: make ready for beta testing

See phase two. Once part of a release (candidate):
- Prepare IUK
- Update upgrade-description files
- Ask beta testers to try the incremental upgrade process
- Catch and fix most remaining bugs
Complete phase three: deploy in production

Once we're happy with the whole thing, ship it, enabled by default, in the next Tails major release.

See child tickets of phase three.
Later

See tickets with Incremental upgrades category on Redmine.

Code

The bulk of the code needed to implement this design lives in the iuk Git repository.
Integration work is being done in the feature/incremental-upgrades branch of the main Tails Git repository.

Random ideas for future improvements

These are not worth creating tickets yet, as it's not even clear these changes are useful enough to put time in it.

Packaging could be more self-contained

Move /etc/sudoers.d/zzz_upgrade and IUK-related user creation from the Tails main Git repository to the tails-iuk Debian package, so that it's more self-contained and easier to test.

Button for aborting upgrade cleanly

Compute and display ETA

Multi-step incremental upgrade

E.g. 0.11 boots after 0.11.1 and 0.11.2 are out. Tails fetches https://tails.boum.org/upgrade/v1/Tails/0.11/i386/stable/upgrades.yml, that shall contain an incremental upgrade path with two target files: the 0.11 to 0.11.1 IUK, and the 0.11.1 to 0.11.2 IUK. The upgrader would download these two files and install the two IUKs in the correct order.

sharing upgrade material

Once the incremental upgrade has been applied, I may be proposed to save a copy of the target files to a location of my choosing.

allow one to download target files in the clear

The downloader program could provide an opt-in way to have the download happen in the clear, that is without going through the Tor network. It looks doable given it's a separate process: we may run it as a dedicated user, and reuse the clearnet infrastructure implemented for the Unsafe Browser.

"Retry with new circuit" button

Circuit throughput varies wildly, and since this is a large download, it'll quickly wear out users' patience if a bad circuit is picked. Or maybe this can happen behind the scenes, e.g.: Automatically switch circuit every X minutes or Y% progress? That could even make fingerprinting the download on the Tor client <-> Entry Node side of the pipe a bit more difficult, for whatever that's worth.

Dialogs and error messages

Not enough memory available

Not enough memory available to check for upgrades.

Make sure this system satisfies the requirements for running Tails.
See file:///usr/share/doc/tails/website/doc/about/requirements.en.html
Try to restart Tails and upgrade again.
Or do a manual upgrade.
See https://tails.boum.org/doc/first_steps/upgrade#manual

Error while checking for upgrades

Could not determine whether an upgrade is available from our website.

Check your network connection, and restart Tails to try upgrading again.

If the problem persists, go to file:///usr/share/doc/tails/website/doc/upgrade/error/check.en.html.

Debugging information

...

Upgrade available

You should upgrade to Tails 0.22.

For more information about this new version, go to https://tails.boum.org/news/version_0.22/.

Note that:

It is recommended to close all the open applications during the upgrade.
Downloading the upgrade might take a long time, from several minutes to a few hours.
The networking will be disabled after downloading the upgrade.

Download size: 201 MB

Do you want to upgrade now?

[Upgrade later] [Upgrade now]

New version available

You should do a manual upgrade to Tails 0.22.

For more information about this new version, go to https://tails.boum.org/news/version_0.22/.

It is not possible to automatically upgrade your device to this new version.

To learn how to do a manual upgrade, go to https://tails.boum.org/doc/first_steps/upgrade#manual

Downloading upgrade

Downloading the upgrade to Tails 0.22...

Error while downloading the upgrade

The upgrade could not be downloaded.

Check your network connection, and restart Tails to try upgrading again.

If the problem persists, go to file:///usr/share/doc/tails/website/doc/upgrade/error/download.en.html.

Debugging information

...

Upgrading the system

Your Tails device is being upgraded...

For security reasons, the networking is now disabled.

Error while installing the upgrade

An error occured while installing the upgrade.

Your Tails device needs to be repaired and might be unable to restart.

Please follow the instructions at file:///usr/share/doc/tails/website/doc/upgrade/error/install.en.html

Debugging information

...

Restart Tails

Your Tails device was successfully upgraded.

Some security features were temporarily disabled.
You should restart Tails on the new version as soon as possible.

Do you want to restart now?

[Restart later] [Restart now]