support macos in jenkins run_distributions script

tools/jenkins/run_distribution.sh

@@ -32,6 +32,10 @@
 # linuxbrew installation of a selected language
 set -ex
 
+if [ "$platform" == "linux" ]; then
+
+  if [ "$dist_channel" == "homebrew" ]; then
+
     sha1=$(sha1sum tools/jenkins/grpc_linuxbrew/Dockerfile | cut -f1 -d\ )
     DOCKER_IMAGE_NAME=grpc_linuxbrew_$sha1
 
@@ -53,3 +57,41 @@ docker run $DOCKER_IMAGE_NAME bash -l \
           npm set unsafe-perm true; \
           rvm use ruby-2.1; \
           $command"
+
+  else
+    echo "Unsupported $platform dist_channel $dist_channel"
+    exit 1
+  fi
+
+elif [ "$platform" == "macos" ]; then
+
+  if [ "$dist_channel" == "homebrew" ]; then
+    which brew # TODO: for debug, can be removed later
+    brew list -l
+    rm -rf /tmp/homebrew-test
+    mkdir -p /tmp/homebrew-test
+    git clone https://github.com/Homebrew/homebrew.git /tmp/homebrew-test
+    cd /tmp/homebrew-test
+    # TODO: Uncomment these when the general structure of the script is verified
+    # PATH=/tmp/homebrew-test/bin:$PATH brew tap homebrew/dupes
+    # PATH=/tmp/homebrew-test/bin:$PATH brew install zlib
+    # PATH=/tmp/homebrew-test/bin:$PATH brew install openssl
+    # PATH=/tmp/homebrew-test/bin:$PATH brew tap grpc/grpc
+    # PATH=/tmp/homebrew-test/bin:$PATH brew install --without-python google-protobuf
+    # PATH=/tmp/homebrew-test/bin:$PATH brew install grpc
+    PATH=/tmp/homebrew-test/bin:$PATH brew list -l
+    brew list -l
+    cd ~/ 
+    rm -rf /tmp/homebrew-test
+    echo $PATH # TODO: for debug, can be removed later
+    brew list -l # TODO: for debug, can be removed later
+
+  else
+    echo "Unsupported $platform dist_channel $dist_channel"
+    exit 1
+  fi
+
+else
+  echo "unsupported platform $platform"
+  exit 1
+fi