Add Ruby-Hello application with Firecracker support

[lupsalexandra33]

This is a Draft PR for the Ruby-Hello application integration. I am following the standard Unikraft catalog structure (similar to other examples) to provide a simple Ruby unikernel example. I am opening this draft to get feedback on the current setup and guidance on build-time errors I am encountering.

Current Progress

1. App Integration: Added Config.uk, Makefile, and Makefile.uk for the ruby-hello application.

2. Setup Automation: Updated the top-level setup.sh to include lib-ruby and required dependencies (lib-newlib, lib-pthread-embedded).

3. Firecracker: Included a draft fc.x86_64.json for testing the application on Firecracker.

4. Documentation: Added a standard README.md with build and run instructions.

Current Blockers & Challenges

1. Ruby Version: I am currently using Ruby 2.6.0 from the lib-ruby repository.

2. Build Errors & Sequence:

I. Missing Auxiliary Files: The build first fails because it cannot find config.guess and config.sub.
II. Manual Workaround: If I manually add these files to the tool/ directory, the process moves forward but hits a second, more critical error.
III. Syntax Error: In the ./configure stage, I get: ./configure: line 4112: syntax error near unexpected token 'fi'.

Root Cause: This appears to be a compatibility issue between Ruby 2.6's older Autotools macros and the modern Autoconf environment on my host, which generates an invalid configuration script.

Fixes #25

[Copilot]

Pull request overview

Adds a new ruby-hello Unikraft catalog application intended to demonstrate running a simple Ruby script, including draft Firecracker configuration and repo setup wiring.

Changes:

• Extend top-level setup.sh to fetch Ruby-related libraries (lib-ruby, lib-newlib, lib-pthread-embedded).
• Introduce a new ruby-hello/ app directory with Unikraft catalog scaffolding (Config.uk, Makefile, Makefile.uk, app setup script).
• Add initial runtime assets and docs (helloworld.rb, fc.x86_64.json, README.md) for Firecracker execution.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
setup.sh	Adds cloning of Ruby and required dependency libraries into repos/.
ruby-hello/setup.sh	Creates workdir/ and symlinks required core/libs into place for building the app.
ruby-hello/README.md	Documents setup/build/run steps for the Ruby hello app.
ruby-hello/Makefile.uk	Registers the app with Unikraft’s build system and adds rootfs-related flags.
ruby-hello/Makefile	Defines the build invocation for the app (currently differs from established catalog Makefile pattern).
ruby-hello/helloworld.rb	Provides a minimal Ruby script to run in the unikernel.
ruby-hello/fc.x86_64.json	Draft Firecracker VM config to boot the resulting unikernel.
ruby-hello/Config.uk	Kconfig entry for enabling the app and selecting required libraries.

Suppressed comments (1)

ruby-hello/fc.x86_64.json:5

• boot_args passes /helloworld.rb, but this Firecracker config does not provide an initrd_path nor any vfs.fstab rootfs mount (unlike other apps that pass a file path, e.g., c-fs/fc.x86_64.json:3-6). As-is, the guest is unlikely to have /helloworld.rb available at runtime unless it is built into the image by some other mechanism.

    "kernel_image_path": "build/ruby-hello_kvm-x86_64",
    "boot_args": "ruby-hello_kvm-x86_64 -- /helloworld.rb"
  },

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[razvand]

Squash both commits into a single one. Be sure you sign the commit:

I get this error when building:

./lib/autoconf/general.m4:204: AC_HELP_STRING is expanded from...                                                              
configure.ac:4001: the top level                                                                                               
configure.ac:4027: warning: AC_C_BIGENDIAN should be used with AC_CONFIG_HEADERS                                               
configure: error: cannot find required auxiliary files: config.guess config.sub                                                
make[3]: *** [/home/monkey/razvand/orgs/unikraft/maintainer-tools/workdir/libs/ruby/Makefile.uk:589: /home/monkey/razvand/orgs/unikraft/catalog-core/ruby-hello/workdir/build/libruby/.configured] Error 1   

Does the build work for you?