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当我们需要修改内核参数时，可以使用sysctl 模块。

比如，我们在shell中会使用

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echo 'vm.swappiness=1' >> /etc/sysctl.conf

来修改内核的swappiness参数，但是如果在ansible脚本中，直接这样写，会破坏幂等性。

每次执行ansible脚本都会添加一行配置，很丑。所以ansible提供了sysctl 模块。

sysctl 可以对值进行设置，如果需要查询可以使用shell 模块。

  • name：变量名
  • value：值
  • reload：文件被更新时，是否使用 sysctl -p reload 文件
  • state：是在文件中 移除(absent)或者设置(present)
  • sysctl_file：如果不是默认文件，指定其他文件
  • sysctl_set：使用sysctl 命令设置，不一定需要reload 文件

使用方法

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Usage:
 sysctl [options] [variable[=value] ...]

Options:
  -a, --all            display all variables
  -A                   alias of -a
  -X                   alias of -a
      --deprecated     include deprecated parameters to listing
  -b, --binary         print value without new line
  -e, --ignore         ignore unknown variables errors
  -N, --names          print variable names without values
  -n, --values         print only values of a variables
  -p, --load[=<file>]  read values from file
  -f                   alias of -p
      --system         read values from all system directories
  -r, --pattern <expression>
                       select setting that match expression
  -q, --quiet          do not echo variable set
  -w, --write          enable writing a value to variable
  -o                   does nothing
  -x                   does nothing
  -d                   alias of -h

 -h, --help     display this help and exit
 -V, --version  output version information and exit

For more details see sysctl(8).

ansible-doc sysctl 文档

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> SYSCTL    (/usr/lib/python2.7/site-packages/ansible/modules/system/sysctl.py)

        This module manipulates sysctl entries and optionally performs a `/sbin/sysctl -p' after changing them.

OPTIONS (= is mandatory):

- ignoreerrors
        Use this option to ignore errors about unknown keys.
        (Choices: yes, no)[Default: False]

= name
        The dot-separated path (aka `key') specifying the sysctl variable.
        (Aliases: key)[Default: None]

- reload
        If `yes', performs a `/sbin/sysctl -p' if the `sysctl_file' is updated. If `no', does not reload `sysctl' even if the
        `sysctl_file' is updated.
        (Choices: yes, no)[Default: yes]

- state
        Whether the entry should be present or absent in the sysctl file.
        (Choices: present, absent)[Default: present]

- sysctl_file
        Specifies the absolute path to `sysctl.conf', if not `/etc/sysctl.conf'.
        [Default: /etc/sysctl.conf]

- sysctl_set
        Verify token value with the sysctl command and set with -w if necessary
        (Choices: yes, no)[Default: False]
        version_added: 1.5


- value
        Desired value of the sysctl key.
        (Aliases: val)[Default: None]


AUTHOR: David CHANIAL (@davixx) <david.chanial@gmail.com>
        METADATA:
          status:
          - stableinterface
          supported_by: core

示例

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EXAMPLES:
# Set vm.swappiness to 5 in /etc/sysctl.conf
- sysctl:
    name: vm.swappiness
    value: 5
    state: present

# Remove kernel.panic entry from /etc/sysctl.conf
- sysctl:
    name: kernel.panic
    state: absent
    sysctl_file: /etc/sysctl.conf

# Set kernel.panic to 3 in /tmp/test_sysctl.conf
- sysctl:
    name: kernel.panic
    value: 3
    sysctl_file: /tmp/test_sysctl.conf
    reload: no

# Set ip forwarding on in /proc and do not reload the sysctl file
- sysctl:
    name: net.ipv4.ip_forward
    value: 1
    sysctl_set: yes
# Set ip forwarding on in /proc and in the sysctl file and reload if necessary
- sysctl:
    name: net.ipv4.ip_forward
    value: 1
    sysctl_set: yes
    state: present
    reload: yes