Git and git-review will be used to pull and push code from/to the ONOS repository, so they need to be installed. To streamline the code review process, it is highly recommended that contributors install
sudo apt-get install git sudo apt-get install git-review
For more info about git-review refer to this link
If you're using a Mac, you may need to manually upgrade the
$ sudo pip install --upgrade setuptools
ONOS is a large project comprising of multiple relatively independent modules that lend themselves to be built in parallel, resulting in much faster. This is why the project chose to build via Bazel. Developers should install Bazel (0.27.0 at the time of writing) before they can build the project themselves.