1，templates 使用规则

• 文本文件，嵌套有脚本（使用模板编程语言编写）
• Jinja2 语言，使用字面量，有下面形式
  • 字符串：使用单引号或双引号
  • 数字：整数，浮点数
  • 列表：[item1,item2,...]
  • 元组：(item1,item2,....)
  • 字典：{key1:value1,key2:value2,...}
  • 布尔型：true/false
• 算术运算：+ , - , * , / , // , % , **
• 比较操作：==, != , > , >= , <
• 逻辑运算：and, or, not
• 流表达式：For if When

2， when

• 条件测试：如果需要根据变量、facts 或此前任务的执行结果来做为某 task 执行与否的前提时要用到条件测试，通过 when 语句实现，在 task 中使用，jinja2 的语法格式
• when 语句
• 在 task 后添加 when 子句即可使用条件测试；when 语句支持 jinja2 表达式语法
• 示例

- name: "shutdown RedHat flavored systems"  command: /sbin/shutdown -h now  when: ansible_os_family == "RedHat"

• 示例2：如果操作系统版本为 centos7 或 6，copy 对应文件

---- hosts: websrvs  remote_user: root  tasks:    - name: add user nginx      user: name=nginx state=present group=nginx    - name: Install Nginx      yum: name=nginx state=present    - name: copy conf file to centos7      template: src=nginx.conf.c7.j2 dest=/etc/nginx/nginx.conf      when: ansible_distribution_major_version == "7"    - name: copy conf file to centos6      template: src=nginx.conf.c6.j2 dest=/etc/nginx/nginx.conf      when: ansible_distribution_major_version == "6"    - name: start  Nginx      service: name=nginx state=started enabled=ture

3， 迭代：with_items

• 迭代：当有需要重复执行的任务时，可以使用迭代机制
  • 对迭代项的引用，固定变量名为 item
  • 要在 task 中使用 with_items 给定要迭代的元素列表
  • 列表格式：
    • 字符串
    • 字典
• 示例

---- hosts: websrvs  remote_user: root  tasks:    - name: create some files      file: name=/tmp/{
   { item }}  state=touch      with_items:        - file1        - file2        - file3

• 迭代嵌套子变量

---- hosts: websrvs  remote_user: root  tasks:    - name: add some groups      group: name={
   { item }} state=present      with_items:        - group1        - group2        - group3    - name: add some users      user: name={
   { item.name }} group={
   { item.group }} state=present      with_items:        - { name: 'user1', group: 'group1' }          - { name: 'user2', group: 'group2' }          - { name: 'user3', group: 'group3' }

4，Playbook 中 template for if

{% for vhost in nginx_vhosts %}server{    listen {
   { vhost.listen | default('80 default_server') }};    {% if vhost.server_name is defined %}    server_name {
   { vhost.server_name }};    {% endif %};    {% if vhost.root is defined %}    root {
   { vhost.root }};    {% endif %}}{% endfor %}

4.1 for 示例

• 列表方式

// testfor1.yml---- hosts: websrvs  remote_user: root  vars:    ports:      - 81      - 82  tasks:    - name: copy conf      template: src=for1.conf.j2 dest=/tmp/for1.conf

// templates/for1.conf.j2{% for port in ports %}server {    listen {
   { port }}}{% endfor %}

// 执行结果server {    listen 81}server {    listen 82}

• 字典方式

// testfor2.yml---- hosts: websrvs  remote_user: root  vars:    ports:      - listen_port: 83      - listen_port: 84  tasks:    - name: copy conf      template: src=for1.conf.j2 dest=/tmp/for2.conf

// templates/for2.conf.j2{% for port in ports %}server {    listen {
   { port.listen_port }}}{% endfor %}

// 执行结果server {    listen 83}server {    listen 84}

• 多个键值对

// testfor3.yml---- hosts: websrvs  remote_user: root  vars:    ports:      - web1:        port: 85        name: web1.test.com        rootdir: /data/website1      - web2:        port: 86        name: web2.test.com        rootdir: /data/website2  tasks:    - name: copy conf      template: src=for3.conf.j2 dest=/tmp/for3.conf

// templates/for3.conf.j2{% for i in ports %}server {    listen {
   { i.port }}    servername: {
   { i.name }}    documentroot: {
   { i.rootdir }}}{% endfor %}

// 执行结果server {    listen 85    servername: web1.test.com    documentroot: /data/website1}server {    listen 86    servername: web2.test.com    documentroot: /data/website2}

4.1 if 示例

• for 嵌套 if

// testfor4.yml---- hosts: websrvs  remote_user: root  vars:    ports:      - web1:        port: 85        name: web1.test.com        rootdir: /data/website1      - web2:        port: 86       # name: web2.test.com        rootdir: /data/website2  tasks:    - name: copy conf      template: src=for4.conf.j2 dest=/tmp/for4.conf

// templates/for4.conf.j2{% for i in ports %}server {        listen {
   { i.port }}        {% if i.name is defined %}        servername: {
   { i.name }}        {% endif %}        documentroot: {
   { i.rootdir }}}{% endfor %}

// 执行结果server {    listen 85        servername: web1.test.com        documentroot: /data/website1}server {    listen 86        documentroot: /data/website2}