test and document how dom0 language can be configured to propagate to `sd-app`

[cfm]

• [x] I have searched for duplicates or related issues

Description

Does setting the dom0 locale propagate the new locale to VMs such as sd-app...

• if it happens after Qubes installation?
• if it happens after sdw-admin --apply?

We should test and document how users can expect to set a non-English default locale.

Steps to Reproduce

Not fully isolated, but:

1. Install a non-English langauge $LANG
2. Set $LANG in dom0's /etc/locale.conf
3. Reboot
4. Start the SecureDrop Client

Expected Behavior

If $LANG is a supported language, the Client appears in $LANG.

Actual Behavior

The Client appears in the default VM-level locale of en_US.

Comments

We've previously tested that the Client respects the VM-level $LANG environment variable. We haven't tested the propagation of $LANG from dom0.

[zenmonkeykstop]

Is this a new bug compared to the previous behaviour in 4.1? It's possible we're missing a core qubes package or something that VMs need to inherit the setting (see also the annoying Perl locale warnings in dom0 tests).

[legoktm]

We discussed this in today, conclusion was that this is something we'd like to support, but is not a 4.2 regression and therefore not a release blocker.

[cfm]

Agreed; rescoped from current bug to future feature.

In practice, this means that testing localization of the Workstation is limited to testing that of the Client, as in freedomofpress/securedrop-client#2071.

[deeplow]

I was looking into this briefly yesterday and I couldn't find any in which dom0 exposes to the VM the language it is supposed to be in. Or at least not a mechanism using qubesdb.

So I guess this is a question for the Qubes team: how does Qubes implement localization?

[rocodes]

(Re perl language / locale warnings) see this open issue: https://github.com/QubesOS/qubes-issues/issues/4889