This is a step-by-step guide to building Heron on Mac OS X (versions 10.10 and 10.11).

Step 1 — Install Homebrew

If Homebrew isn’t yet installed on your system, you can install it using this one-liner:

$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Step 2 — Install bazel and other required libraries

brew install bazel
brew install automake
brew install cmake
brew install libtool

Step 3 — Set the following environment variables

$ export CC=/usr/bin/clang
$ export CXX=/usr/bin/clang++
$ echo $CC $CXX

Step 4 — Fetch the latest version of Heron’s source code

$ git clone https://github.com/twitter/heron.git && cd heron

Step 5 — Configure Heron for building with Bazel

$ ./bazel_configure.py

If this configure script fails with missing dependencies, Homebrew can be used to install those dependencies.

Step 6 — Build the project

$ bazel build --config=darwin heron/...

Step 7 — Build the packages

$ bazel build --config=darwin scripts/packages:binpkgs
$ bazel build --config=darwin scripts/packages:tarpkgs

This will install Heron packages in the bazel-bin/scripts/packages/ directory.