docker exrm (many months old, might be way outdated)

docker-compose.yml

# docker-compose.yml

# You are going to get an warning about "Missing beam file elf_format...
# from this link and the stackoverflow one, it looks like it can be ignored
# https://github.com/bitwalker/exrm/issues/107
search_api:
    build: .
    environment:
      MIX_ENV: prod
    command: mix release
    volumes:
        - /some/path:/app
    working_dir: /app

Dockerfile

# This image is designed as a base image to use in creating exrm releases. It
# includes quite a few things that you would not need for just a pure runtime
# but is also suitable to use as a base for a phoenix app (you may need to add
# npm for handling the static assets)

FROM debian:jessie

MAINTAINER Someone <someone@somewhere.com>

ENV DEBIAN_FRONTEND noninteractive

# Get base packages and set the locale
RUN apt-get update && apt-get install -y -qq --no-install-recommends \
    build-essential \
    ca-certificates \
    curl \
    git \
    locales \
    openssl \
    unzip \
    wget && \
    echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen && \
    locale-gen en_US.UTF-8 && \
    /usr/sbin/update-locale LANG=en_US.UTF-8 && \
    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

ENV LANG en_US.UTF-8
ENV LANGUAGE en_US:en
ENV LC_ALL en_US.UTF-8

RUN curl -o /tmp/erlang.deb http://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb && \
    dpkg -i /tmp/erlang.deb && \
    rm -rf /tmp/erlang.deb && \
    apt-get update && apt-get install -y -qq --no-install-recommends \
    # erlang-base=1:18.1 erlang-dev=1:18.1 erlang-eunit=1:18.1 erlang-xmerl=1:18.1 \
    erlang=1:18.1 \
    elixir=1.1* && \
    apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Install local Elixir hex and rebar
RUN /usr/local/bin/mix local.hex --force && \
    /usr/local/bin/mix local.rebar --force && \
    /usr/local/bin/mix hex.info

You should be able to use any current dockerfile that support elixir. I just put the one I used here for reference.