Copy locale.md file below into same directory as your Dockerfile
FROM alpine:3.9
# Install language pack
RUN apk --no-cache add ca-certificates wget && \
wget -q -O /etc/apk/keys/sgerrand.rsa.pub https://alpine-pkgs.sgerrand.com/sgerrand.rsa.pub && \
wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.25-r0/glibc-2.25-r0.apk && \
wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.25-r0/glibc-bin-2.25-r0.apk && \
wget https://github.com/sgerrand/alpine-pkg-glibc/releases/download/2.25-r0/glibc-i18n-2.25-r0.apk && \
apk add glibc-bin-2.25-r0.apk glibc-i18n-2.25-r0.apk glibc-2.25-r0.apk
# Iterate through all locale and install it
# Note that locale -a is not available in alpine linux, use `/usr/glibc-compat/bin/locale -a` instead
COPY ./locale.md /locale.md
RUN cat /locale.md | xargs -i /usr/glibc-compat/bin/localedef -i {} -f UTF-8 {}.UTF-8
# Set the lang, you can also specify it as as environment variable through docker-compose.yml
ENV LANG=en_US.UTF-8 \
LANGUAGE=en_US.UTF-8