摘自：http://www.ansible.com.cn/docs/playbooks_intro.html


Handlers: 在发生改变时执行的操作

（当发生改动时）’notify’ actions 会在 playbook 的每一个 task 结束时被触发,而且即使有多个不同的 task 通知改动的发生, ‘notify’ actions 只会被触发一次.

举例来说,比如多个 resources 指出因为一个配置文件被改动,所以 apache 需要重新启动,但是重新启动的操作只会被执行一次.

- name: template configuration file

template: src=template.j2 dest=/etc/foo.conf

notify:

- restart memcached

- restart apache

‘notify’ 下列出的即是 handlers.

Handlers 是由通知者进行 notify, 如果没有被 notify,handlers 不会执行.不管有多少个通知者进行了 notify,等到 play 中的所有 task 执行完成之后,handlers 也只会被执行一次.

handlers:

- name: restart memcached

service:  name=memcached state=restarted

- name: restart apache

service: name=apache state=restarted

Handlers 最佳的应用场景是用来重启服务,或者触发系统重启操作.

如果你想立即执行所有的 handler 命令,在1.2及以后的版本,你可以这样做:

tasks:

- shell: some tasks go here

- meta: flush_handlers

- shell: some other tasks

在以上的例子中,任何在排队等候的 handlers 会在执行到 ‘meta’ 部分时,优先执行.这个技巧在有些时候也能派上用场.


执行一个playbook

[root@localhost ~]# ansible-playbook -h

Usage: ansible-playbook playbook.yml


Options:

--ask-vault-pass      ask for vault password

-C, --check           don't make any changes; instead, try to predict some

of the changes that may occur

-D, --diff            when changing (small) files and templates, show the

differences in those files; works great with --check

-e EXTRA_VARS, --extra-vars=EXTRA_VARS

set additional variables as key=value or YAML/JSON

--flush-cache         clear the fact cache

--force-handlers      run handlers even if a task fails

-f FORKS, --forks=FORKS

specify number of parallel processes to use

(default=5)

-h, --help            show this help message and exit

-i INVENTORY, --inventory-file=INVENTORY

specify inventory host path

(default=/etc/ansible/hosts) or comma separated host

list.

-l SUBSET, --limit=SUBSET

further limit selected hosts to an additional pattern

--list-hosts          outputs a list of matching hosts; does not execute

anything else

--list-tags           list all available tags

--list-tasks          list all tasks that would be executed

-M MODULE_PATH, --module-path=MODULE_PATH

specify path(s) to module library (default=None)

--new-vault-password-file=NEW_VAULT_PASSWORD_FILE

new vault password file for rekey

--output=OUTPUT_FILE  output file name for encrypt or decrypt; use - for

stdout

--skip-tags=SKIP_TAGS

only run plays and tasks whose tags do not match these

values

--start-at-task=START_AT_TASK

start the playbook at the task matching this name

--step                one-step-at-a-time: confirm each task before running

--syntax-check        perform a syntax check on the playbook, but do not

execute it

-t TAGS, --tags=TAGS  only run plays and tasks tagged with these values

--vault-password-file=VAULT_PASSWORD_FILE

vault password file

-v, --verbose         verbose mode (-vvv for more, -vvvv to enable

connection debugging)

--version             show program's version number and exit


Connection Options:

control as whom and how to connect to hosts


-k, --ask-pass      ask for connection password

--private-key=PRIVATE_KEY_FILE, --key-file=PRIVATE_KEY_FILE

use this file to authenticate the connection

-u REMOTE_USER, --user=REMOTE_USER

connect as this user (default=None)

-c CONNECTION, --connection=CONNECTION

connection type to use (default=smart)

-T TIMEOUT, --timeout=TIMEOUT

override the connection timeout in seconds

(default=30)

--ssh-common-args=SSH_COMMON_ARGS

specify common arguments to pass to sftp/scp/ssh (e.g.

ProxyCommand)

--sftp-extra-args=SFTP_EXTRA_ARGS

specify extra arguments to pass to sftp only (e.g. -f,

-l)

--scp-extra-args=SCP_EXTRA_ARGS

specify extra arguments to pass to scp only (e.g. -l)

--ssh-extra-args=SSH_EXTRA_ARGS

specify extra arguments to pass to ssh only (e.g. -R)


Privilege Escalation Options:

control how and which user you become as on target hosts


-s, --sudo          run operations with sudo (nopasswd) (deprecated, use

become)

-U SUDO_USER, --sudo-user=SUDO_USER

desired sudo user (default=root) (deprecated, use

become)

-S, --su            run operations with su (deprecated, use become)

-R SU_USER, --su-user=SU_USER

run operations with su as this user (default=root)

(deprecated, use become)

-b, --become        run operations with become (does not imply password

prompting)

--become-method=BECOME_METHOD

privilege escalation method to use (default=sudo),

valid choices: [ sudo | su | pbrun | pfexec | doas |

dzdo | ksu ]

--become-user=BECOME_USER

run operations as this user (default=root)

--ask-sudo-pass     ask for sudo password (deprecated, use become)

--ask-su-pass       ask for su password (deprecated, use become)

-K, --ask-become-pass

ask for privilege escalation password

示例：

ansible-playbook playbook.yml -f 10