Skip VM updates if last check was performed <X hours ago

[eloquence]

The launcher app currently checks for updates every single time, which can take a while. It would be good to skip this step if it has been performed very recently.

Open questions:

• Should the launcher GUI be shown to the user at all in this case, or be bypassed entirely?
• What is the maximum amount of time that may pass without checking for updates again?

[eloquence]

Should the launcher GUI be shown to the user at all in this case, or be bypassed entirely?

I would vote to bypass the GUI entirely in this case, and to immediately launch the client instead.

[eloquence]

Nominating as beta requirement as we don't want users to have to wait several minutes if they need to restart the client for any reason during a single session.

[eloquence]

In addition to the client restart scenario, we currently run the "check for updates" after required reboots as well, which means that the dom0 updates take especially long to go through.

[zenmonkeykstop]

So reqs for this are:

• If updater has run within N hours, don't show GUI but go straight to client
• If system has been rebooted by updater, don't show GUI but go straight to client
• Otherwise, show GUI

Also adding:

• In either of the first two cases, log the no-GUI start.

[emkll]

Yes that seems correct @zenmonkeykstop, and i would propose N=8:

• read timestamp in sdw_last_updated flag from ~/.securedrop-launcher
• if sdw_last_updated < 8h and last_required_reboot_performed() [1]: start client
• else show launcher

[1] https://github.com/freedomofpress/securedrop-workstation/blob/master/launcher/sdw_updater_gui/Updater.py#L292

[zenmonkeykstop]

OK, adding an update_skip_delta value (in sec) in config.json, and a "--update-delta" (positive) integer arg to the launcher with Salt setting it appropriately.

Behavior will be:

• if reload flag is set, clear reload flag and skip update check
• if reload flag not set, --update_delta is set and > 0, and if sdw_last_updated - now > update_delta, do update check
• if reload flag not set, --update_delta not set or = 0, do update check