Alpine Crystal image

Alpine image with Crystal installed alongside sufficient packages to build statically-linked Crystal applications for easy deployment and distribution.

Available Docker tags

Each tag links to the relevant Dockerfile.

Tag	Crystal version	Alpine version
latest	0.31.0-r0	v3.10
0.31	0.31.0-r0	v3.10
0.30	0.30.1-r1	v3.10
0.29	0.29.0-r0	v3.10
0.27	0.27.0-r0	v3.9

Usage

For the purposes of these instructions, your application's source code is assumed to be in ./src with the main entry point (or target) in ./src/app.cr.

Add this hack to your main application file to allow you to build a statically-linked executable:

echo '# prevents segfault during static linking on Alpine, ignored otherwise
{% if flag?(:static) %}
  require "llvm/lib_llvm"
  require "llvm/enums"
{% end %}' >> src/app.cr

To compile the application for release:

docker run --rm --user $(id -u) --env UID=$(id -u) --env GID=$(id -g) -it -v $PWD:/app -w /app pgeraghty/alpine-crystal:latest crystal build --static --release --no-debug src/app.cr

This will build a statically-linked app binary in the current directory without symbolic debug info. The additional user flags should avoid restrictive permissions being applied to the generated file.