Docker + older version of Elixir/Phoenix

Question

I have been requested to move an Elixir/Phoenix app to Docker, with which I have no prior experience. The app uses non-latest versions of Elixir and Phoenix so I have had to diverge from the code online which generally focuses on latest versions. That led me to write this Dockerfile

# FROM bitwalker/alpine-elixir:latest
FROM bitwalker/alpine-elixir:1.3.4
MAINTAINER Paul Schoenfelder <paulschoenfelder@gmail.com>

# Important!  Update this no-op ENV variable when this Dockerfile
# is updated with the current date. It will force refresh of all
# of the base images and things like `apt-get update` won't be using
# old cached versions when the Dockerfile is built.
ENV REFRESHED_AT=2017-07-26 \
    # Set this so that CTRL+G works properly
    TERM=xterm

# Install NPM
RUN \
    mkdir -p /opt/app && \
    chmod -R 777 /opt/app && \
    apk update && \
    apk --no-cache --update add \
      git make g++ wget curl inotify-tools \
      nodejs nodejs-current-npm && \
    npm install npm -g --no-progress && \
    update-ca-certificates --fresh && \
    rm -rf /var/cache/apk/*

# Add local node module binaries to PATH
ENV PATH=./node_modules/.bin:$PATH \
    HOME=/opt/app

# Install Hex+Rebar
RUN mix local.hex --force && \
    mix local.rebar --force

WORKDIR /opt/app

CMD ["/bin/sh"]

<then it goes on to add some elixir depedencies>

On running

sudo docker build -t phoenix .

I'm ending up with this error and wondering how to get around it? Noting 'current' in the title I'm wondering whether using an older version of nodejs, and if so, how to do that? Beyond that I am open to any and all suggestions

ERROR: unsatisfiable constraints:
  nodejs-current-npm (missing):
    required by: world[nodejs-current-npm]
  musl-1.1.14-r14:
    breaks: musl-dev-1.1.14-r15[musl=1.1.14-r15]

Answer 1

That looks like bitwalker/alpine-elixir issue 5 :

when using tagged images, you may sometimes need to explicitly upgrade packages, as the installed packages are at the versions found when building the image.
Generally it's as simple as adding apk --update upgrade before any commands which install packages.

Indeed, when you compare the old elixir 1.4.4-based Dockerfile , and the latest one , you will see an upgrade first in the latter:

apk --no-cache --update upgrade && \
apk add --no-cache --update --virtual .elixir-build \
...

Try and add that to your Dockerfile.