Cross compiling a release with Apple M1 and Docker

Questions / Help
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1

I am trying to cross-compile an Elixir release within a Docker container for amd64 on a M1 Macbook and I receive the following error when calling mix deps.compile:

The Docker image I am building from is elixir:latest with the --platform=amd64 flag set.

#0 3.446 Error while loading project :decimal at /app/deps/decimal                                                      
#0 3.480 ** (FunctionClauseError) no function clause matching in Keyword.merge/2                                        
#0 3.480                                                                                                                
#0 3.480     The following arguments were given to Keyword.merge/2:
#0 3.480     
#0 3.480         # 1
#0 3.480         [app: nil, aliases: [], build_embedded: false, build_per_environment: true, build_scm: Mix.SCM.Path, config_path: "config/config.exs", consolidate_protocols: true, default_task: "run", deps: [], deps_path: "deps", elixirc_paths: ["lib"], erlc_paths: ["src"], erlc_include_path: "include", erlc_options: [], lockfile: "mix.lock", preferred_cli_env: [], start_permanent: false]
#0 3.480     
#0 3.480         # 2
#0 3.480         Decimal.Mixfile
#0 3.480     
#0 3.480     Attempted function clauses (showing 3 out of 3):
#0 3.480     
#0 3.480         def merge(+keywords1+, -[]-) when +is_list(keywords1)+
#0 3.480         def merge(-[]-, +keywords2+) when -is_list(keywords2)-
#0 3.480         def merge(+keywords1+, +keywords2+) when +is_list(keywords1)+ and -is_list(keywords2)-
#0 3.480     
#0 3.480     (elixir 1.14.4) lib/keyword.ex:979: Keyword.merge/2
#0 3.480     (mix 1.14.4) lib/mix/project.ex:141: Mix.Project.push/3
#0 3.480     (stdlib 4.3.1) lists.erl:1350: :lists.foldl/3

Any suggestions on how to solve this? It builds fine when trying on the same arm64 Docker image so I assume I am missing something.

2

No idea but you could first try the hexpm images.

https://hub.docker.com/u/hexpm

We really need a bot that responds to all Docker questions concerning the elixir image with this.

I tried to add a note to the readme, but the PR has been open for 8 months: Update elixir to link to alternative and similarly official images by adamu · Pull Request #2206 · docker-library/docs · GitHub

3

Cross-/multiplatform images of OTP languages is unsupported since the introduction of the JIT compiler in OTP24.
Docker uses QEMU for that under the hood, which doesn’t support some of the memory magic that happens for JIT, see: Erlang/OTP 25 JIT on AArch64 fails in user mode emulation (#1034) · Issues · QEMU / QEMU · GitLab

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4

Thanks so much for this… that’s a bummer!

5

For posterity: you can set ERL_AFLAGS=“+JMsingle true” and make the JIT more amenable to emulation. Or compile it on a matching machine.

As a last resort, you can try compiling the Erlang VM without JIT and using the emulator, but that’s not recommend (it is slower too).

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