Properly compiling distributable native gems.

Rakefile

@@ -23,7 +23,15 @@ Rake::ExtensionTask.new('grpc_c', spec) do |ext|
   ext.ext_dir = File.join('src', 'ruby', 'ext', 'grpc')
   ext.lib_dir = File.join('src', 'ruby', 'lib', 'grpc')
   ext.cross_compile = true
-  ext.cross_platform = ['x86-mingw32', 'x64-mingw32']
+  ext.cross_platform = [
+    'x86-mingw32', 'x64-mingw32',
+    'x86_64-linux', 'x86-linux',
+    'x86_64-darwin-11',
+    'x86_64-darwin-12',
+    'x86_64-darwin-13',
+    'x86_64-darwin-14',
+    'x86_64-darwin-15'
+  ]
   ext.cross_compiling do |spec|
     spec.files = %w( etc/roots.pem grpc_c.32.ruby grpc_c.64.ruby )
     spec.files += Dir.glob('src/ruby/bin/**/*')
@@ -91,8 +99,8 @@ task 'dlls' do
 
 end
 
-desc 'Build the gem file under rake_compiler_dock'
-task 'gem:windows' do
+desc 'Build the native gem file under rake_compiler_dock'
+task 'gem:native' do
   verbose = ENV['V'] || '0'
 
   docker_for_windows "bundle && rake cross native gem RUBY_CC_VERSION=2.3.0:2.2.2:2.1.6:2.0.0 V=#{verbose}"
@@ -105,7 +113,7 @@ task 'suite:bidi' => 'suite:wrapper'
 task 'suite:server' => 'suite:wrapper'
 task 'suite:pb' => 'suite:server'
 
-task 'gem:windows' => 'dlls'
+task 'gem:native' => 'dlls'
 
 desc 'Compiles the gRPC extension then runs all the tests'
 task all: ['suite:idiomatic', 'suite:bidi', 'suite:pb', 'suite:server']

src/ruby/ext/grpc/extconf.rb

@@ -75,6 +75,7 @@
 
   ENV['EMBED_OPENSSL'] = 'true'
   ENV['EMBED_ZLIB'] = 'true'
+  ENV['ARCH_FLAGS'] = RbConfig::CONFIG['ARCH_FLAG']
   ENV['ARCH_FLAGS'] = '-arch i386 -arch x86_64' if RUBY_PLATFORM =~ /darwin/
 
   output_dir = File.expand_path(RbConfig::CONFIG['topdir'])

third_party/rake-compiler-dock/Dockerfile

@@ -1,7 +1,7 @@
 FROM ubuntu:14.04
 
 RUN apt-get -y update && \
-    apt-get install -y curl git-core mingw-w64 xz-utils build-essential wget unzip
+    apt-get install -y curl git-core mingw-w64 xz-utils build-essential gcc-multilib wget unzip
 
 RUN mkdir -p /opt/mingw && \
     curl -SL http://downloads.sourceforge.net/mingw-w64/i686-w64-mingw32-gcc-4.7.2-release-linux64_rubenvb.tar.xz | \
@@ -103,12 +103,25 @@ RUN bash -c "rvm use 2.3.0 --default && \
     export MAKE=\"make -j`nproc`\" CFLAGS='-s -O1 -fno-omit-frame-pointer -fno-fast-math' && \
     rake-compiler cross-ruby VERSION=2.3.0 HOST=i686-w64-mingw32 && \
     rake-compiler cross-ruby VERSION=2.3.0 HOST=x86_64-w64-mingw32 && \
+    rake-compiler cross-ruby VERSION=2.3.0 HOST=x86_64-linux-gnu && \
     rake-compiler cross-ruby VERSION=2.2.2 HOST=i686-w64-mingw32 && \
     rake-compiler cross-ruby VERSION=2.2.2 HOST=x86_64-w64-mingw32 && \
+    rake-compiler cross-ruby VERSION=2.2.2 HOST=x86_64-linux-gnu && \
     rake-compiler cross-ruby VERSION=2.1.6 HOST=i686-w64-mingw32 && \
     rake-compiler cross-ruby VERSION=2.1.6 HOST=x86_64-w64-mingw32 && \
+    rake-compiler cross-ruby VERSION=2.1.6 HOST=x86_64-linux-gnu && \
     rake-compiler cross-ruby VERSION=2.0.0-p645 HOST=i686-w64-mingw32 && \
     rake-compiler cross-ruby VERSION=2.0.0-p645 HOST=x86_64-w64-mingw32 && \
+    rake-compiler cross-ruby VERSION=2.0.0-p645 HOST=x86_64-linux-gnu && \
+    rm -rf ~/.rake-compiler/tmp/builds ~/.rake-compiler/sources && \
+    find /usr/local/rvm -type d -print0 | sudo xargs -0 chmod g+sw "
+
+RUN bash -c "rvm use 2.3.0 --default && \
+    export MAKE=\"make -j`nproc`\" CFLAGS='-m32 -s -O1 -fno-omit-frame-pointer -fno-fast-math' LDFLAGS='-m32' && \
+    rake-compiler cross-ruby VERSION=2.3.0 HOST=i686-linux-gnu && \
+    rake-compiler cross-ruby VERSION=2.2.2 HOST=i686-linux-gnu && \
+    rake-compiler cross-ruby VERSION=2.1.6 HOST=i686-linux-gnu && \
+    rake-compiler cross-ruby VERSION=2.0.0-p645 HOST=i686-linux-gnu && \
     rm -rf ~/.rake-compiler/tmp/builds ~/.rake-compiler/sources && \
     find /usr/local/rvm -type d -print0 | sudo xargs -0 chmod g+sw "