when

tasks:
  - name: "shutdown Debian flavored systems"
    command: /sbin/shutdown -t now
    when: ansible_os_family == "Debian"

tasks:
  - command: /bin/false
    register: result
    ignore_errors: True
  - command: /bin/something
    when: result|failed
  - command: /bin/something_else
    when: result|success
  - command: /bin/still/something_else
    when: result|skipped

# fact
ansible hostname.example.com -m setup

tasks:
  - shell: echo "only on Red Hat 6, derivatives, and later"
    when: ansible_os_family == "RedHat" and ansible_lsb.major_release|int >= 6

# 变量
vars:
  epic: true

tasks:
    - shell: echo "This certainly is epic!"
      when: epic

tasks:
    - shell: echo "This certainly isn't epic!"
      when: not epic

# jinja2模板
tasks:
    - shell: echo "I've got '{{ foo }}' and am not afraid to use it!"
      when: foo is defined

    - fail: msg="Bailing out. this play requires 'bar'"
      when: bar is not defined

# loop
tasks:
    - command: echo {{ item }}
      with_items: [ 0, 2, 4, 6, 8, 10 ]
      when: item > 5

Loading in Custom Facts

tasks:
    - name: gather site specific fact data
      action: site_facts
    - command: /usr/bin/thingy
      when: my_custom_fact_just_retrieved_from_the_remote_system == '1234'

Applying ‘when’ to roles and includes

- include: tasks/sometasks.yml
  when: "'reticulating splines' in output"

- hosts: webservers
  roles:
     - { role: debian_stock_config, when: ansible_os_family == 'Debian' }

Conditional Imports

---
- hosts: all
  remote_user: root
  vars_files:
    - "vars/common.yml"
    - [ "vars/{{ ansible_os_family }}.yml", "vars/os_defaults.yml" ]
  tasks:
  - name: make sure apache is running
    service: name={{ apache }} state=running

---
# for vars/CentOS.yml
apache: httpd
somethingelse: 42

# for facter
ansible -m yum -a "pkg=facter ensure=installed"
ansible -m yum -a "pkg=ruby-json ensure=installed"

# for ohai
ansible -m yum -a "pkg=ohai ensure=installed"

Selecting Files And Templates Based On Variables

- name: template a file
  template: src={{ item }} dest=/etc/myapp/foo.conf
  with_first_found:
    - files:
       - {{ ansible_distribution }}.conf
       - default.conf
      paths:
       - search_location_one/somedir/
       - /opt/other_location/somedir/

Register Variables

- name: test play
  hosts: all
  tasks:
      - shell: cat /etc/motd
        register: motd_contents

      - shell: echo "motd contains the word hi"
        when: motd_contents.stdout.find('hi') != -1

- name: registered variable usage as a with_items list
  hosts: all
  tasks:
      - name: retrieve the list of home directories
        command: ls /home
        register: home_dirs

      - name: add home dirs to the backup spooler
        file: path=/mnt/bkspool/{{ item }} src=/home/{{ item }} state=link
        with_items: home_dirs.stdout_lines
        # same as with_items: home_dirs.stdout.split()