一、详解
command模块是ansible-core核心模块的一部分,大多数情况下可以使用简化名command;该命令会被执行在所有选择的机器上。
注意事项
- 1、该命令并不会通过shell执行,所以对于环境变量$HOSTNAME以及一些" *", "<", ">", "|", ";" and "&" 操作将不支持,如果想要支持这些功能,可以使用ansible.builtin.shell 模块
1、参数详解
每一个模块都会有传入的参数,模块根据参数来执行具体的任务,相关参数如下:
参数 | 详解 |
---|---|
cmd string | 该模块待执行的命令 |
chdir path | 在执行命令之前,先切换目录 |
creates path | 如果机器节点上该文件存在,则该任务将不会执行(当前机器节点跳过该任务),该校验会在removes校验之前校验 |
removes path | 如果一个文件存在,则该步骤才会执行 |
argv list/ elements=string | 将命令以列表的形式传入 |
注意点
- creates 、removes 、chdir 选项可以在cmd选项之后指定
- 通过指定creates 、removes选项来启用校验模式
- 执行顺序 chdir > creates > removes > cmd
2、argv 与 args 的区别
args是task任务的关键字,与模式是同一级别的;argv 是command模块的参数关键字,用于将命令行以列表的形式传入
二、实例详解
1、playbook yaml文件实例详解
yaml
- name: Return motd to registered var
ansible.builtin.command: cat /etc/motd
register: mymotd
# free-form (string) arguments, all arguments on one line
# 所有的命令在同一行
- name: Run command if /path/to/database does not exist (without 'args')
ansible.builtin.command: /usr/bin/make_database.sh db_user db_name creates=/path/to/database
# free-form (string) arguments, some arguments on separate lines with the 'args' keyword
# 'args' is a task keyword, passed at the same level as the module
# 使用task任务的关键子args,将模块的参数传入模块
- name: Run command if /path/to/database does not exist (with 'args' keyword)
ansible.builtin.command: /usr/bin/make_database.sh db_user db_name
args:
# 当该文件存在的时候,该任务将会被跳过,(即文件不存在,才会执行与removes正好相反)
creates: /path/to/database
# 'cmd' is module parameter
# cmd是command模块的参数
- name: Run command if /path/to/database does not exist (with 'cmd' parameter)
ansible.builtin.command:
cmd: /usr/bin/make_database.sh db_user db_name
creates: /path/to/database
## 尽量采用这种模式的task模板,其他一般会出错
- name: Change the working directory to somedir/ and run the command as db_owner if /path/to/database does not exist
ansible.builtin.command: /usr/bin/make_database.sh db_user db_name
become: yes
become_user: db_owner
args:
chdir: somedir/
creates: /path/to/database
# argv (list) arguments, each argument on a separate line, 'args' keyword not necessary
# 'argv' is a parameter, indented one level from the module
- name: Use 'argv' to send a command as a list - leave 'command' empty
ansible.builtin.command:
argv:
- /usr/bin/make_database.sh
- Username with whitespace
- dbname with whitespace
creates: /path/to/database
- name: Run command using argv with mixed argument formats
ansible.builtin.command:
argv:
- /path/to/binary
- -v
- --debug
- --longopt
- value for longopt
- --other-longopt=value for other longopt
- positional
- name: Safely use templated variable to run command. Always use the quote filter to avoid injection issues
ansible.builtin.command: cat {{ myfile|quote }}
register: myoutput
具体实例如下:
yaml
---
- name: Update web servers
hosts: webservers
remote_user: kafka
tasks:
- name: ls -l
ansible.builtin.command: ls -l
args:
chdir: somedir/
creates: /path/to/database
- name: Write the apache config file
ansible.builtin.template:
src: /srv/httpd.j2
dest: /etc/httpd.conf
2、ansible命令实例详解
bash
ansible hostpattern -i hosts -m command -a 'cmd=ls -l creates=/path/file'
# command是ansible中的默认模块,即如下两个命令一致
ansible web -i hosts -m command -a "hostname"
ansible web -i hosts -a "hostname"
# 常见的命令行实例如下
ansible webservers -m service -a "name=httpd state=started"
ansible webservers -m ping
ansible webservers -m command -a "/sbin/reboot -t now"