Encoding Problems when running an app in docker (Python, Java, Ruby, ...) with Ubuntu Containers (ascii, utf-8)

Question

On my own PC the application runs nice, but when it gets deployed into docker, it fails because of invalid characters.

I am using the ubuntu:latest container and python3, java and ruby.

Answer 1

You need to set the locale correct.

This is the minimal correct Dockerfile:

FROM ubuntu

RUN apt update && apt -y install locales && locale-gen en_US.UTF-8
ENV LANG en_US.UTF-8
ENV LANGUAGE en_US:en
ENV LC_ALL en_US.UTF-8

The usual docker images don't specify a locales. You see it if you bash into it and execute locale:

sudo docker exec -i -t yowsup3 bash

Sources:

• http://jaredmarkell.com/docker-and-locales/
• https://github.com/docker-library/python/issues/13

Answer 2

I tried the above solution and found that the locale-gen command is not available inside my docker.

so add this line above the RUN command or add it in.

RUN apt-get update && apt-get install -y locales && locale-gen en_US.UTF-8

this will now work.

and second ENV LC_ALL en_US.UTF-8 is enough to set most of the variable but it left with the two vacant so that's why we need all 3 to set.