Issue #17815 has been updated by paddor (Patrik Wenger).
This can be closed. I've implemented a Ruby build plugin on v1 and v2.
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Misc #17815: Snapcraft Ruby plugin
https://bugs.ruby-lang.org/issues/17815#change-105943
* Author: paddor (Patrik Wenger)
* Status: Open
* Priority: Normal
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I'm working on a Ruby build plugin for the Snapcraft v2 plugin AP, since the v1 Ruby
plugin does not work on the Ubuntu `core20` image. The v2 API only allows to influence
the build step, which means there's no nice way for the plugin to set environment
variables that apply during runtime. The problem is that the final paths to Ruby's
stdlib are unknown during compile time.
I've got it to work by renaming the `ruby` executable to `ruby.bare` and creating a
wrapper script `ruby` that sets the `$RUBYLIB` and `$GEM_PATH` env variables based on
`$SNAP` before `exec`ing `ruby.bare`. I don't like that it requires a wrapper script
though, since it would have to awkwardly determine the arch-specific stdlib directory to
support any platform. The current wrapper script is this:
```sh
#!/bin/sh
export RUBYLIB="$SNAP/lib/ruby/snap:$SNAP/lib/ruby/snap/x86_64-linux:$RUBYLIB"
export GEM_PATH="$SNAP/lib/ruby/gems/snap:$GEM_PATH"
exec `dirname $0`/ruby.bare "$@"
```
What possible solutions are there? I could maybe fix the shebangs of Ruby executables like
`gem` and `bundle`, but not `ruby` itself since it's binary. Also, I'm not sure if
env variable expansion even works in shebang.
Can the configure script's `--with-search-path` be made to support env variable
expansion during runtime? That still wouldn't solve the issue about the arch-specific
directory.
Python apparently determines its load paths relative to the executable being run. Does
Ruby support anything like that?
Any other ideas?
Current state:
https://github.com/paddor/snapcraft-ruby-plugin-v2
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