Role works on Ubuntu only

[ohathaway]

Please add 'apt' package manager as a dependency to the README. This role doesn't work outside of the Ubuntu family.
TASK [zzet.rbenv : update apt cache] ************************************************************************************************************************************ fatal: [my-host]: FAILED! => {"msg": "The conditional check 'ansible_pkg_mgr == 'apt'' failed. The error was: error while evaluating conditional (ansible_pkg_mgr == 'apt'): 'ansible_pkg_mgr' is undefined\n\nThe error appears to be in '/Users/deploy/.ansible/roles/zzet.rbenv/tasks/apt_build_depends.yml': line 1, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: update apt cache\n ^ here\n"}