Add ruby 2.6 gem build for linux (#5537)

* Add ruby 2.6 gem build for linux

* Add docker hub organization

* Add ruby2.6 in cross compile targets

* Fix tests

* Check mac version

* No need to install php in preparation for mac

kokoro/linux/dockerfile/push_testing_images.sh

@@ -8,7 +8,7 @@ cd -
 
 DOCKERHUB_ORGANIZATION=protobuftesting
 
-for DOCKERFILE_DIR in test/*
+for DOCKERFILE_DIR in test/* release/*
 do
   # Generate image name based on Dockerfile checksum. That works well as long
   # as can count on dockerfiles being written in a way that changing the logical

kokoro/linux/dockerfile/release/ruby_rake_compiler/Dockerfile

+FROM grpctesting/rake-compiler-dock_53c22085d091183c528303791e7771359f699bcf
+
+RUN /bin/bash -l -c "gem install bundler"

kokoro/macos/prepare_build_macos_rc

@@ -18,9 +18,8 @@ export CXX=g++
 
 ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
 source $HOME/.rvm/scripts/rvm
-brew tap homebrew/homebrew-php
 brew uninstall node icu4c
-brew install gflags gpg gpg2 node pcre php56 ruby
+brew install gflags gpg gpg2 node pcre ruby
 
 ##
 # Install Tox

kokoro/release/ruby/linux/prepare_build.sh

@@ -8,9 +8,11 @@ echo 'DOCKER_OPTS="${DOCKER_OPTS} --registry-mirror=https://mirror.gcr.io"' | su
 sudo service docker restart
 
 # Download Docker images from DockerHub
-export DOCKERHUB_ORGANIZATION=grpctesting
+DOCKERHUB_ORGANIZATION=protobuftesting
+DOCKERFILE_DIR=kokoro/linux/dockerfile/release/ruby_rake_compiler
+DOCKERFILE_PREFIX=$(basename $DOCKERFILE_DIR)
+export RAKE_COMPILER_DOCK_IMAGE=${DOCKERHUB_ORGANIZATION}/${DOCKERFILE_PREFIX}_$(sha1sum $DOCKERFILE_DIR/Dockerfile | cut -f1 -d\ )
 
 # All artifacts come here
 mkdir artifacts
 export ARTIFACT_DIR=$(pwd)/artifacts
-

kokoro/release/ruby/macos/ruby/ruby_build_environment.sh

@@ -47,7 +47,7 @@ EOF
 
 MAKE="make -j8"
 
-for v in 2.5.0 2.4.0 2.3.0 2.2.2 2.1.6 2.0.0-p645 ; do
+for v in 2.6.0 2.5.1 2.4.0 2.3.0 ; do
   ccache -c
   rake -f "$CROSS_RUBY" cross-ruby VERSION="$v" HOST=x86_64-darwin11 MAKE="$MAKE"
 done

ruby/Rakefile

@@ -70,13 +70,13 @@ else
 
   task 'gem:windows' do
     require 'rake_compiler_dock'
-    RakeCompilerDock.sh "bundle && IN_DOCKER=true rake cross native gem RUBY_CC_VERSION=2.5.0:2.4.0:2.3.0:2.2.2:2.1.6:2.0.0"
+    RakeCompilerDock.sh "bundle && IN_DOCKER=true rake cross native gem RUBY_CC_VERSION=2.6.0:2.5.0:2.4.0:2.3.0"
   end
 
   if RUBY_PLATFORM =~ /darwin/
     task 'gem:native' do
       system "rake genproto"
-      system "rake cross native gem RUBY_CC_VERSION=2.5.0:2.4.0:2.3.0:2.2.2:2.1.6:2.0.0"
+      system "rake cross native gem RUBY_CC_VERSION=2.6.0:2.5.1:2.4.0:2.3.0"
     end
   else
     task 'gem:native' => [:genproto, 'gem:windows']