Provision ec2 instance with ansible

gistfile1.txt

---
- hosts: localhost
  connection: local
  gather_facts: true
  become: true

  vars_files:
    - vars.yml

  tasks:
  - name: Launch ec2 on aws
    ec2:
      access_key="{{ ec2_access_key }}"
      secret_key="{{ ec2_secret_key }}"
      keypair="{{ ec2_keypair }}"
      image="{{ ec2_image }}"
      type="{{ ec2_type }}"
      region={{ ec2_region }}
      instance_tags="{'Name':'{{ ec2_tag }}'}"
      count_tag="{'Name':'{{ ec2_tag }}'}"
      exact_count="{{ ec2_instance_count }}"
      wait=true
    register: ec2
  - name: Add new instance to the local host group
    local_action: lineinfile dest=hosts regexp="{{ item.public_dns_name }}" insertafter="[launched]" line="{{ item.public_dns_name }} ansible_ssh_private_key_file=/Users/$USER/.ssh/"{{ ssh_key }}""
    with_items: "{{ ec2.instances }}"
  - name: Wait for instance to come up
    local_action: wait_for host={{ item.public_dns_name }}
      port={{ wait_for_port }} delay=180 timeout=320 state=started
    with_items: "{{ ec2.instances }}"

hosts file
[local]
localhost ansible_python_interpreter=/usr/local/bin/python

[launched]