What am I missing when russifying the console?

Question

linux

locale -a

C
C.UTF-8
en_US.utf8
POSIX
ru_RU.utf8
ru_UA.utf8

locale

LANG=ru_UA.utf8
LANGUAGE=ru_UA.utf8
LC_CTYPE="ru_UA.utf8"
LC_NUMERIC="ru_UA.utf8"
LC_TIME="ru_UA.utf8"
LC_COLLATE="ru_UA.utf8"
LC_MONETARY="ru_UA.utf8"
LC_MESSAGES="ru_UA.utf8"
LC_PAPER="ru_UA.utf8"
LC_NAME="ru_UA.utf8"
LC_ADDRESS="ru_UA.utf8"
LC_TELEPHONE="ru_UA.utf8"
LC_MEASUREMENT="ru_UA.utf8"
LC_IDENTIFICATION="ru_UA.utf8"
LC_ALL=ru_UA.utf8

date
Пт 15 янв 2021 11:40:13 EET

rm -vf README.md
removed 'README.md'

Ubuntu 20.04 LTS inside Docker on WIN10.
The server has similar locale settings, but both messages are displayed in Russian.
What did I miss?

Some more data.

I configured the locale via dpkg-reconfigure locales.
By default, I chose ru_UA.UTF-8.
In Docker, for some reason, this setting is not picked up. Every new locale session shows POSIX.
I had to fix it via export in .bashrc.

Just in case: cat /etc/default/locale

#  File generated by update-locale
LANG=ru_UA.UTF-8

Everything seems to be correct. But why such a problem?

On the server for Russification, I always simply performed dpkg-reconfigure locales and no additional gestures were required.
I understand that in Docker the axis is severely cut, maybe something is missing. But already broke the brain of what exactly.

I will be grateful for help.

Answer 1

Unlike Debian, in Ubuntu the localization files are placed in a separate language-pack-ru package, the installation of which solves the problem.