ansible使用5-Variables

变量命名

支持数字、字母、下划线

有效：foo_port, foo5
无效：foo-port, foo port, foo.port, 12

playbook定义

- hosts: webservers
  vars:
    http_port: 80

jinja2模板使用变量

My amp goes to {{ max_amp_value }}
template: src=foo.cfg.j2 dest={{ remote_install_path }}/foo.cfg

Jinja2 Filters

格式化数据

{{ some_variable | to_nice_json }}
{{ some_variable | to_nice_yaml }}

使用条件表达式

tasks:

  - shell: /usr/bin/foo
    register: result
    ignore_errors: True

  - debug: msg="it failed"
    when: result|failed

  # in most cases you'll want a handler, but if you want to do something right now, this is nice
  - debug: msg="it changed"
    when: result|changed

  - debug: msg="it succeeded"
    when: result|success

  - debug: msg="it was skipped"
    when: result|skipped

强制变量定义

{{ variable | mandatory }}

变量默认值

{{ some_variable | default(5) }}

变量省略值

- name: touch files with an optional mode
  file: dest={{item.path}} state=touch mode={{item.mode|default(omit)}}
  with_items:
    - path: /tmp/foo
    - path: /tmp/bar
    - path: /tmp/baz
      mode: "0444"

列表

# 最小值
{{ list1 | min }}
# 最大值
{{ [3, 4, 2] | max }}
# 唯一值
{{ list1 | unique }}
# 并集
{{ list1 | union(list2) }}
# 交集
{{ list1 | intersect(list2) }}
# 补集（存在list1,不存在list2）
{{ list1 | difference(list2) }}
# 对称差集 (不同时存在每个列表)
{{ list1 | symmetric_difference(list2) }}

版本比较

{{ ansible_distribution_version | version_compare('12.04', '>=') }}

# <, lt, <=, le, >, gt, >=, ge, ==, =, eq, !=, <>, ne
# 版本分析strict=True，默认值false

随机数

{{ ['a','b','c']|random }} => 'c'
{{ 59 |random}} * * * * root /script/from/cron
{{ 100 |random(step=10) }}  => 70
{{ 100 |random(1, 10) }}    => 31
{{ 100 |random(start=1, step=10) }}    => 51

洗牌(shuffle)

{{ ['a','b','c']|shuffle }} => ['c','a','b']
{{ ['a','b','c']|shuffle }} => ['b','c','a']

其他

# 列表转字符串
{{ list | join(" ") }}

# 文件全路径
{{ path | basename }}

# 目录全路径
{{ path | dirname }}

# 用户目录（～）全路径
{{ path | expanduser }}

#　link的路径
{{ path | readlink }}

#　Base64加解密
{{ encoded | b64decode }}
{{ decoded | b64encode }}

# 文件的sha1sum
{{ filename | sha1 }}

bool

- debug: msg=test
  when: some_string_value | bool

正则

vars:
  url: "http://example.com/users/foo/resources/bar"

tasks:
    - shell: "msg='matched pattern 1'"
      when: url | match("http://example.com/users/.*/resources/.*")

    - debug: "msg='matched pattern 2'"
      when: url | search("/users/.*/resources/.*")

# convert "ansible" to "able"
{{ 'ansible' | regex_replace('^a.*i(.*)$', 'a\\1') }}

# convert "foobar" to "bar"
{{ 'foobar' | regex_replace('^f.*o(.*)$', '\\1') }}

- hosts: app_servers
  vars:
       app_path: "{{ base_path }}/22"

Facts

'''bash
ansible hostname -m setup

{{ ansible_devices.sda.model }}
{{ ansible_hostname }}
'''

Turning Off Facts

- hosts: whatever
  gather_facts: no

本地facts(自定义facts)

# /etc/ansible/facts.d/preferences.fact
[general]
asdf=1
bar=2

# 命令
ansible <hostname> -m setup -a "filter=ansible_local"

# API
"ansible_local": {
        "preferences": {
            "general": {
                "asdf" : "1",
                "bar"  : "2"
            }
        }
 }

# 引用
{{ ansible_local.preferences.general.asdf }}

# 部署
- hosts: webservers
  tasks:
    - name: create directory for ansible custom facts
      file: state=directory recurse=yes path=/etc/ansible/facts.d
    - name: install custom impi fact
      copy: src=ipmi.fact dest=/etc/ansible/facts.d
    - name: re-read facts after adding custom fact
      setup: filter=ansible_local

Fact Caching

{{ hostvars['asdf.example.com']['ansible_os_family'] }}

# /etc/ansible/ansible.cfg
[defaults]
fact_caching = redis
fact_caching_timeout = 86400
# seconds

yum install redis
service redis start
pip install redis

Registered Variables

- hosts: web_servers

  tasks:

     - shell: /usr/bin/foo
       register: foo_result
       ignore_errors: True

     - shell: /usr/bin/bar
       when: foo_result.rc == 5

Accessing Complex Variable Data

{{ ansible_eth0["ipv4"]["address"] }}
{{ ansible_eth0.ipv4.address }}
{{ foo[0] }}

Magic Variables, and How To Access Information About Other Hosts

{{ hostvars['test.example.com']['ansible_distribution'] }}

{% if 'webserver' in group_names %}
   # some part of a configuration file that only applies to webservers
{% endif %}

{% for host in groups['app_servers'] %}
   # something that applies to all app servers.
{% endfor %}

# example
{% for host in groups['app_servers'] %}
   {{ hostvars[host]['ansible_eth0']['ipv4']['address'] }}
{% endfor %}

Variable File Separation

---

- hosts: all
  remote_user: root
  vars:
    favcolor: blue
  vars_files:
    - /vars/external_vars.yml

  tasks:

  - name: this is just a placeholder
    command: /bin/echo foo

---
# in the above example, this would be vars/external_vars.yml
somevar: somevalue
password: magic

Passing Variables On The Command Line

ansible-playbook release.yml --extra-vars "version=1.23.45 other_variable=foo"

#example
---

- hosts: '{{ hosts }}'
  remote_user: '{{ user }}'

  tasks:
     - ...

ansible-playbook release.yml --extra-vars "hosts=vipers user=starbuck"
or
--extra-vars '{"pacman":"mrs","ghosts":["inky","pinky","clyde","sue"]}'
or
--extra-vars "@some_file.json"

Variable Precedence: Where Should I Put A Variable?

#组变量默认值在group_vars/all
---
# file: /etc/ansible/group_vars/all
# this is the site wide default
ntp_server: default-time.example.com

# 组变量，覆盖组默认变量
---
# file: /etc/ansible/group_vars/boston
ntp_server: boston-time.example.com

# 主机变量，覆盖组变量
---
# file: /etc/ansible/host_vars/xyz.boston.example.com
ntp_server: override.example.com

role variable precedence

---
# file: roles/x/defaults/main.yml
# if not overridden in inventory or as a parameter, this is the value that will be used
http_port: 80

# 不能覆盖默认值
---
# file: roles/x/vars/main.yml
# this will absolutely be used in this role
http_port: 80

# 使用这种方式覆盖默认值
roles:
   - { name: apache, http_port: 8080 }

roles:
   - { role: app_user, name: Ian    }
   - { role: app_user, name: Terry  }
   - { role: app_user, name: Graham }
   - { role: app_user, name: John   }

# roles/common/vars/main.yml
roles:
   - { role: common_settings }
   - { role: something, foo: 12 }
   - { role: something_else }