Some documentation about locale setting in arch wiki: https://wiki.archlinux.org/index.php/locale

In Dockerfile, adjust LANG to your desired locale. You can add more than one locale in /etc/locale.gen to have a choice later.

ENV LANG=en_US.utf8 RUN echo "$LANG UTF-8" >> /etc/locale.gen RUN locale-gen RUN update-locale --reset LANG=$LANG 

Some documentation about locale setting in arch wiki: https://wiki.archlinux.org/index.php/locale

In Dockerfile, adjust LANG to your desired locale. You can add more than one locale in /etc/locale.gen to have a choice later.

Works on debian, arch, but locale-gen misses on fedora:

ENV LANG=en_US.utf8 RUN echo "$LANG UTF-8" >> /etc/locale.gen RUN locale-gen RUN update-locale --reset LANG=$LANG 

More general is localedef, works on fedora, too:

ENV LANG=en_US.UTF-8 localedef --verbose --force -i en_US -f UTF-8 en_US.UTF-8