gistfile1.txt

---
- name: Test
  hosts: 127.0.0.1
  connection: local
  gather_facts: no
  vars:
  - modules: ['--with-http_image_filter_module', '--with-http_xslt_module']
  - recompile: false

  tasks:
  - name: Get installed modules
    shell: nginx -V
    register: nginx_flags
    ignore_errors: True

  - set_fact:
      recompile: true
    when: "item not in nginx_flags.stderr"
    with_items: modules

  - name: Configure nginx
    debug: msg="./configure --prefix=/opt/nginx {{modules|join(' ') }}"
    when: recompile == true