Unexpected error while executing my app

[Sylvain Corsini]

Hi,

I've created a Dockerfile for my phoenix application.
My app is built using mix release thanks to the distillery package.

Here is my Dockerfile:

FROM elixir:1.6-alpine

ENV API_VERSION 0.0.1
ENV MIX_HOST 8080

RUN mkdir /app && \
  apk --no-cache add tar bash

COPY ./archives/api_${API_VERSION}.tar.gz /app/api.tar.gz

RUN cd /app && \
  tar -zxvf /app/api.tar.gz && \
  rm /app/api.tar.gz && \
  apk del tar && \
  rm -rf /var/cache/apk/*

WORKDIR /app/releases/${API_VERSION}

EXPOSE $MIX_HOST
VOLUME /app

CMD ["./api.sh", "foreground"]

But I got the following error:

/app/erts-9.3.1/bin/erlexec: line 1: syntax error: unexpected "("

While it's perfectly working on my host machine.

Do you have any idea ?

Thanks,

[c0b]

the erlexec should be a binary but its content got a shell script? some shelling debugging technique may apply, like CMD ["sh", "-x", "./api.sh", "foreground"] ? and you can some head lines of the api.sh ?

[Sylvain Corsini]

Hi,
Yeah erlexec is a binary, the api.sh seems well formatted and is auto-generated by destillery.
I just changed my Dockerfile as above:

FROM alpine:3.8

RUN mkdir -p /app && \
  apk --no-cache add elixir && \
  apk --update --no-cache add erlang-runtime-tools && \
  mix local.hex --force && \
  mix local.rebar --force

VOLUME ["/app"]

WORKDIR "/app"

EXPOSE 4000

CMD ["iex"]

I mount my elixir app into the /app folder and then run mix phx.server.
I forgot the destillery package for the moment.
I think something is missing to properly execute the bundled app inside the dockerfile.

[Kirill Kovalevskiy]

I got this error building on OSX M1 chip. Running file command on erlexec show that it is build for ARM architecture even withing Docker container.

If you on ARM processor aka. Mac M1 go to Docker Setting -> Experimental and enable Use New Virtualization Framework
This will add new docker buildx command.

Now build your image with Docker like so

docker buildx build --platform linux/amd64 -t my_image_tag .