Docker build fails

[JohnAZoidberg]

Hi, somebody was demoing this firmware at coscup 2025, so I wanted to try it out.
I'm struggling with the regular build so I tried docker but it also fails:

> docker compose run --rm prk rake                                                                                                    
Specify a task:                                                                                                                                                                   
  rake pico       # build for RP2040                                                                                                                                              
  rake pico2      # build for RP2350

> docker compose run --rm prk rake pico
rake test
GIT CHECKOUT DETACH /prk_firmware/lib/picoruby/build/repos/host/mruby-compiler2 -> 25dabbfc0a0053b2dc9bc0dc87b48b3247898aad
HEAD is now at 25dabbf manually revert change only for mruby/c
<internal:/usr/lib/ruby/3.4.0/rubygems/core_ext/kernel_require.rb>:136:in 'Kernel#require': cannot load such file -- erb (LoadError)
        from <internal:/usr/lib/ruby/3.4.0/rubygems/core_ext/kernel_require.rb>:136:in 'Kernel#require'
        from templates/template.rb:4:in '<main>'
rake aborted!
Command failed with status (1): [templates/template.rb]
/prk_firmware/lib/picoruby/build/repos/host/mruby-compiler2/mrbgem.rake:44:in 'block (3 levels) in <top (required)>'
/prk_firmware/lib/picoruby/build/repos/host/mruby-compiler2/mrbgem.rake:43:in 'block (2 levels) in <top (required)>'
/prk_firmware/lib/picoruby/build/repos/host/mruby-compiler2/mrbgem.rake:51:in 'block (2 levels) in <top (required)>'
/prk_firmware/lib/picoruby/build/repos/host/mruby-compiler2/mrbgem.rake:48:in 'Array#each'
/prk_firmware/lib/picoruby/build/repos/host/mruby-compiler2/mrbgem.rake:48:in 'block in <top (required)>'
/prk_firmware/lib/picoruby/lib/mruby/gem.rb:73:in 'BasicObject#instance_eval'
/prk_firmware/lib/picoruby/lib/mruby/gem.rb:73:in 'MRuby::Gem::Specification#setup'
/prk_firmware/lib/picoruby/lib/mruby/gem.rb:358:in 'Array#each'
/prk_firmware/lib/picoruby/lib/mruby/gem.rb:358:in 'MRuby::Gem::List#each'
/prk_firmware/lib/picoruby/tasks/mrbgems.rake:6:in 'block in <top (required)>'
/prk_firmware/lib/picoruby/lib/mruby/build.rb:18:in 'BasicObject#instance_eval'
/prk_firmware/lib/picoruby/lib/mruby/build.rb:18:in 'block in MRuby.each_target'
/prk_firmware/lib/picoruby/lib/mruby/build.rb:17:in 'Hash#each'
/prk_firmware/lib/picoruby/lib/mruby/build.rb:17:in 'MRuby.each_target'
/prk_firmware/lib/picoruby/tasks/mrbgems.rake:1:in '<top (required)>'
/prk_firmware/lib/picoruby/Rakefile:29:in 'Kernel#load'
/prk_firmware/lib/picoruby/Rakefile:29:in '<top (required)>'
Tasks: TOP => prism_templates
(See full trace by running task with --trace)
rake aborted!
Command failed with status (1): [rake test]
/prk_firmware/Rakefile:127:in 'block (2 levels) in <top (required)>'
/prk_firmware/Rakefile:126:in 'block in <top (required)>'
/prk_firmware/Rakefile:71:in 'block in <top (required)>'
Tasks: TOP => all => libmruby
(See full trace by running task with --trace)

[hasumikin]

Due to the progress of PicoRuby, PRK is now outdated. Fixes needed.

[JohnAZoidberg]

Ah thanks, looking forward to the fix, fyi @zachfeldman
We couldn't build it with the regular instructions either.