Changes/Reset-locale-if-not-available

Reset locale if not available

Summary

When logging in over ssh or another mechanism, locale settings are forwarded. If the destination does not support that locale, C.UTF-8 will be used instead.

Owner

• Name: Zbigniew Jędrzejewski-Szmek
• Email: zbyszek@in.waw.pl
• Release notes owner:

Current status

• Targeted release: Fedora 30
• Last updated: 2019-01-08
• Tracker bug:

Detailed Description

This is a continuation of Changes/Remove glibc-langpacks-all from buildroot. With that change implemented, it is much more likely for a system to only support C.UTF-8 or some other small set of locales. When logging in into such an image from a normal system that uses a "full" locale like en_US.UTF-8 or the equivalent for another language, those locale settings are forwarded, resulting in a session with invalid locale settings and errors from various tools.

The same problem could occur previously, for example when logging in from a desktop with LANG=fr_FR.UTF-8 to a container with only en_EN.UTF-8 installed.

To avoid this, the locale setting will be reset to C.UTF-8 if the current setting is "invalid" (not found).

We already have a mechanism to reset locale information if it is unusable. /etc/profile.d/lang.sh will unset Japanese/Korean/Chinese/... locales only the tty, because the kernel cannot display such fonts properly, so we switch to en_US.UTF-8 to get something displayed. The same mechanism will be used for this.

Benefit to Fedora

Avoid stupid warnings like

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LC_CTYPE = "fr_FR.UTF-8",
	LANG = "en_US.UTF-8"
        ...
       are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US.UTF-8").

Scope

• Proposal owners:
  • Provide a patch to /etc/profile.d/lang.{sh,csh} to check if the inherited locale is present, and if not, reset to C.UTF-8.

• Other developers: n/a

• Release engineering: https://pagure.io/releng/issue/8036
  • List of deliverables: N/A

• Policies and guidelines: no changes needed

• Trademark approval: N/A (not needed for this Change)

Upgrade/compatibility impact

I think this should be beneficial in all cases. I doubt that anyone runs with broken locale settings on purpose.

How To Test

Login to a different machine with a locale not installed on that machine. Verify that the locale is set to C.UTF-8. If the locale is installed on the target machine, it should not be reset.

User Experience

Slightly easier ssh sessions. See also 1432426.

Dependencies

None.

Contingency Plan

Revert the change to /etc/profile.d/lang.*.

• Contingency mechanism: revert the patch, rebuild setup package
• Contingency deadline: any time before relase
• Blocks release? no
• Blocks product? no

Documentation

None needed.

Release Notes

Locale settings will be reset to C.UTF-8 when logging into a machine which does not have the locale that is used on the source machine.