Set an UTF-8 locale as default, not POSIX

[dolmen]

Problem

The default locale of the node image is POSIX:

$ docker run --rm node:latest locale                                       
LANG=
LANGUAGE=
LC_CTYPE="POSIX"
LC_NUMERIC="POSIX"
LC_TIME="POSIX"
LC_COLLATE="POSIX"
LC_MONETARY="POSIX"
LC_MESSAGES="POSIX"
LC_PAPER="POSIX"
LC_NAME="POSIX"
LC_ADDRESS="POSIX"
LC_TELEPHONE="POSIX"
LC_MEASUREMENT="POSIX"
LC_IDENTIFICATION="POSIX"
LC_ALL=

node:19 has the following locales built-in:

$ docker run --rm node:19 locale -a
C
C.UTF-8
POSIX

The POSIX locale doesn't recognize UTF-8 (wc -m counts characters, not bytes).

$ docker run --rm node:latest bash -c 'echo -n 💩 | wc -m'
4
$ docker run --rm node:latest bash -c 'echo -n 💩 | LC_CTYPE=C.UTF-8 wc -m'
1

It is possible to manually enable C.UTF-8:

$ docker run --rm --env LC_CTYPE=C.UTF-8 node:latest bash -c 'echo -n 💩 | wc -m'
1

However in 2023, who doesn't need a locale supporting Unicode? ASCII is a bad default as it doesn't match a 2023 development environment.

Solution

Set LC_CTYPE=C.UTF-8 in the node image. Probably in file /etc/environment.

[MikeMcC399]

This suggestion applies to Debian images.

Official Debian Docker images for trixie, bookworm and bullseye each set locale to POSIX values.
(The same is also true for Ubuntu images 26.04, 24.04 & 22.04, for comparison.)

Node.js Docker images do not change the Debian locale in the build templates. They use what the base image sets.

Changing to a different locale setting would be a breaking change and would therefore be problematic.

Reference

https://www.debian.org/doc/manuals/debian-reference/ch08.en.html#_the_locale