Archive:Vondruch/Draft RubyGuidelines

JRuby Gems
Although Fedora 19 has fully functioning JRuby integrated with system RubyGems, we have decided to not include the JRuby specific packaging guidelines here, as they need some more work. They will appear here as soon as we feel that we've got everything covered properly. You can contact us on Ruby-SIG mailing list in case of any questions about the prepared JRuby packaging guidelines.

There are three basic categories of ruby packages: ruby gems, non-gem ruby packages, and applications written in ruby. These guidelines contain sections common to all of these as well as sections which apply to each one individually. Be sure to read all the guidelines relevant to the type of ruby package you are building.

Ruby Compatibility

Each Ruby package must indicate it depends on a Ruby interpreter (this does not apply to ruby gem packages). Use ruby(release) virtual requirement to achieve that:

Requires: ruby(release)

If the package requires Ruby of certain version(s), make the requirement versioned like this:

Requires: ruby(release) >= 1.9.1

Alternate interpreters
Alternate Ruby interpreters (currently JRuby) also Provide: ruby(release). This implies, that pure RubyGems packages (these are shared among interpreters) should not have Requires: ruby or Requires: jruby to have their dependencies satisfied by any of these interpreters.

Over specified ruby(release) versioning
Please note, that if the ruby(release) version requirement is too specific, it may cause an unexpected interpreter to be drawn in. E.g. ruby(release) = 1.8 will require JRuby package, since it is the only package that provides it.

Different Interpreters Compatibility

Most of the pure Ruby packages will work on all Ruby interpreters. There are however cases, when the packages use interpreter-specific functions (like fork()) and won't run on other interpreters (JRuby). In this case, the package should require that interpreter. For example, a package that uses fork should explicitly specify Requires: ruby. In case of such package, packager should file a bug to ask upstream to provide support for other interpreter(s). This should be documented in specfile.

Shebang lines

On Fedora, /usr/bin/ruby is implemented via Rubypick. Rubypick is a tool similar to RVM or rbenv. It allows choosing interpreter to execute Ruby script. Rubypick routes anything executed via /usr/bin/ruby to /usr/bin/ruby-mri or /usr/bin/jruby. By default, it runs MRI (Matz's Ruby Implementation), but user can explicitly specify the interpreter by using _mri_ or _jruby_ as a first parameter. For example:

ruby _jruby_ jruby_script.rb
gem _mri_ install foo
rails _jruby_ s

Using the RUBYPICK environment variable can achieve the same results. The environment variable can be used to set one interpreter as the global default:

export RUBYPICK=_jruby_
ruby jruby_script.rb  # Will use jruby
gem install foo        # Will also use jruby

Ruby executables that are known to only run on one Ruby implementation should use that specific implementation in their shebang - #!/usr/bin/ruby-mri or #!/usr/bin/jruby to ensure that they run using that implementation. All other code should use #!/usr/bin/ruby.

Naming Guidelines

• Packages that contain Ruby Gems must be called rubygem-%{gem_name}.

• The name of a ruby extension/library package must start with the interpreter it is built for (ruby, jruby, etc) and then the UPSTREAM name. For example: ruby-UPSTREAM. If the upstream name UPSTREAM contains ruby, that should be dropped from the name. For example, the SQLite database driver for ruby is called sqlite3-ruby. The corresponding Fedora package should be called ruby-sqlite3, and not ruby-sqlite3-ruby.

• Application packages that mainly provide user-level tools that happen to be written in Ruby must follow the general NamingGuidelines instead.

Macros

Non-gem ruby packages and ruby gem packages install to certain standard locations. The ruby-devel and rubygems-devel packages contain macros useful for the respective package types. Alternate ruby interpreters will have equivalent locations (To be added to this table later)

Macro	Expanded path	Usage
From ruby-devel; intended for non-gem packages.
%{ruby_vendorarchdir}	/usr/lib{64}/ruby/vendor_ruby	Place for architecture specific (e.g. *.so) files.
%{ruby_vendorlibdir}	/usr/share/ruby/vendor_ruby	Place for architecture independent (e.g. *.rb) files.
%{ruby_sitearchdir}	/usr/local/lib{64}/ruby/site_ruby	Place for local architecture specific (e.g. *.so) files.
%{ruby_sitelibdir}	/usr/local/share/ruby/site_ruby	Place for local architecture independent (e.g. *.rb) files.
From rubygems-devel; intended for gem packages
%{gem_dir}	/usr/share/gems	Top directory for the Gem structure.
%{gem_instdir}	%{gem_dir}/gems/%{gem_name}-%{version}	Directory with the actual content of the Gem.
%{gem_libdir}	%{gem_instdir}/lib	The lib folder of the Gem.
%{gem_cache}	%{gem_dir}/cache/%{gem_name}-%{version}.gem	The cached Gem.
%{gem_spec}	%{gem_dir}/specifications/%{gem_name}-%{version}.gemspec	The Gem specification file.
%{gem_docdir}	%{gem_dir}/doc/%{gem_name}-%{version}	The rdoc documentation of the Gem.
%{gem_extdir_mri}	%{_libdir}/gems/ruby/%{gem_name}-%{version}	The directory for MRI Ruby Gem extensions.

Interpreter independence and directory macros

You may have noticed that the table above has different directories for non-gem libraries on different ruby interpreters but only a single set of directories for rubygem libraries. This is because code written for one ruby interpreter will often run on all ruby interpreters that Fedora ships (ruby, jruby, etc). However, some code uses methods that are not available on all interpreters (see Different Interpreters Compatibility). Rubygems have a facility to ship different versions of the code in the same gem so that the gem can run on all versions of the interpreter so we only need to have one common directory for rubygems that all the interpreters can use.

The standard ruby %{vendorlib} directories lack this facility. For this reason, non-gem libraries need to be placed in per-interpreter directories and must have a separate subpackage (or package depending on upstream) for each interpreter that they support.

Libraries

These guidelines only apply to Ruby packages whose main purpose is providing a Ruby library; packages that mainly provide user-level tools that happen to be written in Ruby must follow the ruby applications guidelines instead.

RubyGems

RubyGems are Ruby's own packaging format. Gems contain a lot of the same metadata that RPM's need, making fairly smooth interoperation between RPM and Gems possible. This guideline ensures that Gems are packaged as RPM's in a way that such RPM's fit cleanly with the rest of the distribution and to make it possible for the end user to satisfy dependencies of a Gem by installing the appropriate RPM-packaged Gem.

Both RPM's and Gems use similar terminology --- there are specfiles, package names, dependencies etc. for both. To keep confusion to a minimum, terms relating to Gem concepts will be explicitly refereed to with the word 'Gem' prefixed, eg 'Gem specification' (.gemspec). An unqualified 'package' in the following always means an RPM.

• Spec files must contain a definition of %{gem_name} which is the name from the Gem's specification.
• The Source of the package must be the full URL to the released Gem archive; the version of the package must be the Gem's version.
• The package must BuildRequires: rubygems-devel to pull in the macros needed to build.
• There should not be any rubygem Requires nor Provides listed, since those are autogenerated.
• There should not be Requires: ruby(release), unless you want to explicitly specify Ruby version compatibility. Automatically generated dependency on RubyGems (Requires: ruby(rubygems)) is enough.

Filtering Requires and Provides

Runtime requires and provides are automatically generated by RPM's dependency generator. However, it can sometimes throw in additional dependencies contrary to reality. To fix this, the dependency generator needs to be overridden so that the additional dependencies can be filtered out. See Packaging:AutoProvidesAndRequiresFiltering for details.

Building gems

Since gems aren't a standard archive format that rpm knows about and they encapsulate both an archive format and information to build the ruby library building an rpm from a gem looks a little different from other rpms.

A sample spec for building gems would look like this:

%prep
%setup -q -n  %{gem_name}-%{version}

# Modify the gemspec if necessary
# Also apply patches to code if necessary
%patch0 -p1

%build
# Create the gem as gem install only works on a gem file
gem build ../%{gem_name}-%{version}.gemspec

# %%gem_install compiles any C extensions and installs the gem into ./%%gem_dir
# by default, so that we can move it into the buildroot in %%install
%gem_install

%install
mkdir -p %{buildroot}%{gem_dir}
cp -a ./%{gem_dir}/* %{buildroot}%{gem_dir}/

# If there were programs installed:
mkdir -p %{buildroot}%{_bindir}
cp -a ./%{_bindir}/* %{buildroot}%{_bindir}

# If there are C extensions, copy them to the extdir.
mkdir -p %{buildroot}%{gem_extdir_mri}
cp -a .%{gem_extdir_mri}/{gem.build_complete,*.so} %{buildroot}%{gem_extdir_mri}/

%prep

Since RPM 4.14, gems are supported archive format that rpm recognizes, so we can call %setup -n %{gem_name}-%{version} to tell rpm what the directory the gem has unpacked into. At the same directory level, the %{gem_name}-%{version}.gemspec is created automatically as well. This .gemspec file will be used to rebuild the gem later. If we need to modify the .gemspec (for instance, if the version of dependencies is wrong for Fedora or the .gemspec is using old, no longer supported fields) we would do it here. Patches to the code itself can also be done here.

Different Guidelines for Fedora 26 and older
In Fedora 26 and older releases, the rubygem %prep section has to be slightly different, since the %setup macro cannot expand the gem yet. Please use the following snippet to mimic the RPM 4.14 %setup macro functionality:

%prep
gem unpack %{SOURCE0}
gem spec %{SOURCE0} -l --ruby > %{gem_name}-%{version}.gemspec

%setup -q -D -T -n  %{gem_name}-%{version}

# Modify the gemspec if necessary
# Also apply patches to code if necessary
%patch0 -p1

The rest of the package can stay the same for all Fedora versions.

%build

Next we build the gem. Because %gem_install only operates on gem archives, we next recreate the gem with gem build. The gem file that is created is then used by %gem_install to build and install the code into the temporary directory, which is ./%{gem_dir} by default. We do this because the %gem_install command both builds and installs the code in one step so we need to have a temporary directory to place the built sources before installing them in %install section.

%gem_install macro accepts two additional options:

-n <gem_file>

Allows to override gem used for installation. This might get useful for converting legacy spec, so you might specify %{SOURCE0} as a gem for installation.

-d <install_dir>

Might override the gem installation destination. However we do not suggest to use this option.

The %gem_install macro must not be used to install into the %{buildroot}

%install

Here we actually install into the %{buildroot}. We create the directories that we need and then copy what was installed into the temporary directories into the %{buildroot} hierarchy. Finally, if this ruby gem creates shared objects the shared objects are moved into the arch specific %{gem_extdir_mri} path.

Patching required gem versions

One common patching need is to change overly strict version requirements in the upstream .gemspec. This may be because upstream's .gemspec only mentions versions that they've explicitly tested against but we know that a different version will also work or because we know that the packages we ship have applied fixes for problematic behavior without bumping the version number (for instance, backported fixes). To adjust such dependecies, you can use %gemspec_add_dep and %gemspec_remove_dep macros.

For example, if you wanted to use any version of Aruba instead of the overly specific version requested by upstream, you could use in %prep section following two lines:

%gemspec_remove_dep -g aruba "~> 0.14.2"
%gemspec_add_dep -g aruba

Use macros only on top of generated .gemspec
The %gemspec_add_dep and %gemspec_remove_dep macros works reliably only on .gemspec generated using ruby spec command. Please don't use the macros on upstream .gemspec files.

Be sure to test
Do not simply change versions without testing that the new version works. There are times the upstream is overly strict but there are also times when the version requirement was specified because a specific bug was encountered or the API changed in a minor release.

Packaging for Gem and non-Gem use

Packaging for non-Gem use is no longer needed
Originally, rubygem modules were not placed in ruby's library path, so we packaged rubygems for use with both gems and non-gems. This allowed code that used require('ARubyModulePackagedAsAGem'); to function. The current rubygem module adds all gems to the ruby library path when it is require'd. So, packagers must not create non-Gem subpackages of rubygems for new packages. Since the majority of Ruby packages in Fedora are now packaged as installed gems, you may need to patch the code to use require('rubygem') as early in the program as possible to ensure that these ruby components are properly found. Packages for ruby gems that currently create a non-gem subpackage should be adapted to stop shipping the non-gem subpackage (with a proper Obsoletes and Provides in the main rubygem package).

Non-Gem Packages

Non-Gem Ruby packages must require ruby-devel package at build time with a BuildRequires: ruby-devel, and may indicate the minimal ruby version they need for building.

Build Architecture and File Placement

The following only affects the files that the package installs into %{ruby_vendorarchdir} and %{ruby_vendorlibdir} (the actual Ruby library files). All other files in a Ruby package must adhere to the general Fedora packaging conventions.

Site versus Vendor
Previously, %{ruby_sitelibdir} and %{ruby_sitearchdir} were used. However, as they are meant only for local installations, please use %{ruby_vendorlibdir} and %{ruby_vendorarchdir} instead.

Pure Ruby packages

Pure Ruby packages must be built as noarch packages.

The Ruby library files in a pure Ruby package must be placed into %{ruby_vendorlibdir} (or its proper subdirectory). The specfile must use this macro.

Ruby packages with binary content/shared libraries

For packages with binary content, e.g., database drivers or any other Ruby bindings to C libraries, the package must be architecture specific.

The binary files in a Ruby package with binary content must be placed into %{ruby_vendorarchdir} (or its proper subdirectory). The Ruby files in such a package should be placed into %{ruby_vendorlibdir}. The specfile must use these macros.

For packages which create C shared libraries using extconf.rb

export CONFIGURE_ARGS="--with-cflags='%{optflags}'"

should be used to pass CFLAGS to Makefile correctly. Also, to place the files into the correct folders during build, pass --vendor to extconf.rb like this:

extconf.rb --vendor

Applications

Applications are

• programs that provide user-level tools or
• web applications, typically built using Rails, Sinatra or similar frameworks.

The RPM packages must obey FHS rules. They should be installed into %{_datadir}. The following macro can help you:

%global app_root %{_datadir}/%{name}

These packages typically have no "Provides" section, since no other libraries or applications depend on them.

Here's an abbreviated example:

%global app_root %{_datadir}/%{name}

Summary: Deltacloud REST API
Name: deltacloud-core
Version: 0.3.0
Release: 3%{?dist}
Group: Development/Languages
License: ASL 2.0 and MIT
URL: http://incubator.apache.org/deltacloud
Source0: http://gems.rubyforge.org/gems/%{name}-%{version}.gem
Requires: rubygem-haml
#...
Requires(post):   chkconfig
#...
BuildRequires: rubygem-haml
#...
BuildArch: noarch

%description
The Deltacloud API is built as a service-based REST API.
You do not directly link a Deltacloud library into your program to use it.
Instead, a client speaks the Deltacloud API over HTTP to a server
which implements the REST interface.

%package doc
Summary: Documentation for %{name}
Group: Documentation
Requires:%{name} = %{version}-%{release}

%description doc
Documentation for %{name}

%prep
%setup -q -n %{name}-%{version}

%build

%install
mkdir -p %{buildroot}%{app_root}
mkdir -p %{buildroot}%{_initddir}
mkdir -p %{buildroot}%{_bindir}
cp -r * %{buildroot}%{app_root}
mv %{buildroot}%{app_root}/support/fedora/%{name} %{buildroot}%{_initddir}
find %{buildroot}%{app_root}/lib -type f | xargs chmod -x
chmod 0755 %{buildroot}%{_initddir}/%{name}
chmod 0755 %{buildroot}%{app_root}/bin/deltacloudd
rm -rf %{buildroot}%{app_root}/support
rdoc --op %{buildroot}%{_defaultdocdir}/%{name}

%post
# This adds the proper /etc/rc*.d links for the script
/sbin/chkconfig --add %{name}

%files
%{_initddir}/%{name}
%{_bindir}/deltacloudd
%dir %{app_root}/
%{app_root}/bin
#...

%files doc
%{_defaultdocdir}/%{name}
%{app_root}/tests
%{app_root}/%{name}.gemspec
%{app_root}/Rakefile

%changelog
#...

Note, that although the source is a RubyGem, we have to install the files manually under %{_datadir}/%{name}, %{_bindir}, etc. to follow FHS and general packaging guidelines. If additional Fedora specific files (systemd .service files, configurations) are required, they should be

• added via another %SOURCE tags

Source1: deltacloudd-fedora

• placed into appropriate locations during %install stage

install -m 0755 %{SOURCE1} %{buildroot}%{_bindir}/deltacloudd

Running test suites

If there is test suite available for the package (even separately, for example not included in the gem but available in the upstream repository), it should be run in %check. The test suite is the only automated tool which can assure basic functionality of the package. Running it is especially helpful when mass rebuilds are required. You may skip test suite execution when not all build dependencies are met but this must be documented in the specfile. The missing build dependencies to enable the test suite should be packaged for Fedora as soon as possible and the test suite re-enabled.

The tests should not be run using Rake - Rake almost always draws in some unnecessary dependencies like hoe or gemcutter. For similar reasons, it is good if Bundler dependency can be avoided. Also try to avoid code coverage frameworks such as SimpleCov and Coveralls.

Testing With Different Ruby Implementations

To run tests with different Ruby implementation such as JRuby, you need to BuildRequires: jruby. Then use Rubypick's interpreter switching:

ruby _jruby_ -Ilib -e 'Dir.glob "./test/test_*.rb", &method(:require)'

If your package is running unittests for ruby-mri and it is intended to run under alternate interpreters then it needs to run the unittests under all alternate interpreters as well. This is the only method we have to check compatibility of the code under each interpreter. The same rules apply that you can omit this if libraries you need are unavailable for a specific alternate interpreter but you must have a comment to explain.

Testing frameworks usage

The Ruby community supports many testing frameworks. The following sections demonstrate how to execute test suites using the more common of them.

MiniTest / Test::UNIT

MiniTest as well as Test::UNIT are shipped with Ruby. To use them, you need to use BuildRequires: rubygem-minitest or BuildRequires: rubygem-testunit) respectively. To execute the test suite you can use something like:

%check
ruby -Ilib -e 'Dir.glob "./test/**/*_test.rb", &method(:require)'

You may need to adjust -Ilib to be -Ilib:test, or you may need to use a slightly different matching pattern for test_*.rb, etc. Packagers are expected to use the right pattern for each gem.

RSpec

To run tests using RSpec >= 3 you must BuildRequires: rubygem-rspec and use something like:

%check
rspec -Ilib spec

Test suites not included in the package

Sometimes you have to get the tests separately from upstream's gem package. As an example lets suppose you're packaging rubygem-delorean, version 1.2.0, which is hosted on Github. Tests are not included in the Gem itself, so you need to get them and adjust the specfile accordingly:

# git clone https://github.com/bebanjo/delorean.git && cd delorean
# git checkout v1.2.0
# tar -czf rubygem-delorean-1.2.0-specs.tgz spec/
Source1: %{name}-%{version}-specs.tgz

# ...
%prep
%setup -q -n %{gem_name}-%{version} -b 1

# ...

%check
pushd ./%{gem_instdir}
# Link the test suite into the right place in source tree.
ln -s %{_builddir}/spec .

# Run tests
rspec spec
popd

# ...

• Make sure to include the version of the tests in the source name, so that when updating to new version, rpmbuild will fail because it won't find the proper %{SOURCE1} (and this will remind you to update the tests, too).
• Add the commands you used to get the tests into the specfile as comments. This will make it a lot easier the next time you will need to get them.
• Run the tests as you normally would.