kubespray is provided through the GitHub repository (https://github.com/kubernetes-incubator/kubespray/tags), as shown in the following screenshot:

Because kubespray is an Ansible playbook, not a binary, you can download the latest version (as of May 2018, version 2.5.0 is the latest) of the zip or tar.gz to your Ansible machine directly and unarchive it with the following command:

//download tar.gz format
ansible_machine$ curl -LO https://github.com/kubernetes-incubator/kubespray/archive/v2.5.0.tar.gz


//untar
ansible_machine$ tar zxvf v2.5.0.tar.gz 


//it unarchives under kubespray-2.5.0 directory
ansible_machine$ ls -F
get-pip.py  kubespray-2.5.0/  v2.5.0.tar.gz


//change to kubespray-2.5.0 directory
ansible_machine$ cd kubespray-2.5.0/