Multi-platform docker image build fails

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1

Hi,

I’m trying to build a multi-platform Docker image based on elixir:1.17-otp-27. However, I’ve encountered an issue: the jason library fails to compile on arm64 because my host machine is running on amd64 architecture. I’ve also tried building the image on an arm64 machine, but then the build step for amd64 fails.

Does anyone have any suggestions on how to resolve this issue? I prefer not to create separate image tags, as the elixir:1.17-otp-27 base image already seems to supports both architectures.

Steps to reproduce:

  • Create new project: mix new myapp
  • Add jasonas dependency in the mix.exs file: {:jason, "~> 1.4"}
  • Create Dockerfile with the following contents:
FROM elixir:1.17-otp-27

WORKDIR /app

COPY . .

RUN MIX_ENV=prod mix deps.get
RUN MIX_ENV=prod mix compile
RUN MIX_ENV=prod mix release
  • Build the image: docker buildx build --platform linux/amd64,linux/arm64 -t myapp_test .

This is the output:

 => ERROR [linux/arm64 5/6] RUN MIX_ENV=prod mix compile                                                                21.1s
------
 > [linux/arm64 5/6] RUN MIX_ENV=prod mix compile:
6.777 ==> jason
6.779 Compiling 10 files (.ex)
17.80 Compiling lib/encode.ex (it's taking more than 10s)
19.47 Compiling lib/decoder.ex (it's taking more than 10s)
20.03 Generated jason app
20.07 could not compile dependency :jason, "mix compile" failed. Errors may have been logged above. You can recompile this dependency with "mix deps.compile jason --force", update it with "mix deps.update jason" or clean it with "mix deps.clean jason"
20.84 Segmentation fault (core dumped)
------
WARNING: No output specified with docker-container driver. Build result will only remain in the build cache. To push result image into registry use --push or to load image into docker use --load
Dockerfile:9
--------------------
   7 |     
   8 |     RUN MIX_ENV=prod mix deps.get
   9 | >>> RUN MIX_ENV=prod mix compile
  10 |     RUN MIX_ENV=prod mix release
--------------------
ERROR: failed to solve: process "/bin/sh -c MIX_ENV=prod mix compile" did not complete successfully: exit code: 139

Is there anything else I could do to build the same tag for both architectures? Thanks in advance :slight_smile:

2

A shot in the dark, maybe installing build-essential with the distro’s package manager could help? Though I don’t think jason has any native dependencies…

1 Like
3

Is it specifically jason? Does it work for other libraries?

There have been issues in the past with qemu and the Erlang JIT, though they usually manifest earlier. Try setting ERL_FLAGS="+JMsingle true" and see if that helps.

4 Likes
4

Actually jason library had nothing to do with the problem. It was just the first library on my dependency list which failed with the error message.

Adding RUN ERL_FLAGS="+JMsingle true" MIX_ENV=prod mix compile fixed the issue for multi arch build, thank you!

I’m wondering if this flag is only used during the compilation step it has no negative effect on the runtime?

5

It does not effect runtime if you only enable it during compilation. The flag disables some safeguards put in place that limits what an attacker can do if they find a vulnerability in the JIT.

2 Likes