Ansibleでvagrant plugin install ref: http://qiita.com/ikuwow/items/207ccc862b7a9f8858dc

vagrant-plugin-install1.yml

ASK: [List Installed Vagrant Plugins] ****************************************
ok: [localhost]

TASK: [Install Vagrant Plugins] ***********************************************
skipping: [localhost] => (item=vagrant-omnibus)
skipping: [localhost] => (item=vagrant-vbguest)
skipping: [localhost] => (item=vagrant-cachier)
skipping: [localhost] => (item=vagrant-vbox-snapshot)
skipping: [localhost] => (item=vagrant-aws)
skipping: [localhost] => (item=vagrant-digitalocean)

vagrant-plugin-install2.yml

---
- hosts: localhost
  connection: local
  gather_facts: no
  tasks: 
    - name: List Installed Vagrant Plugins
      shell: "vagrant plugin list | awk '{ print $1 }'"
      changed_when: false
      register: vagrant_plugin_list

    - name: Install Vagrant Plugins
      shell: "vagrant plugin install {{item}}"
      with_items:
        - vagrant-omnibus
        - vagrant-vbguest
        - vagrant-cachier
        - vagrant-vbox-snapshot
        - vagrant-aws
        - vagrant-digitalocean
      when: item not in vagrant_plugin_list.stdout_lines