在Ansible中设置变量值时如何使用算术? [英] How to use arithmetic when setting a variable value in Ansible?

问题描述

我想将系统事实用于主机乘以数字/百分比作为变量的基础.我要专门做的是使用ansible_memtotal_mb值并将其乘以.80以得到ramsize，然后将其用于设置Couchbase值.我一直在尝试以下行的不同变体.我不确定是否有可能，但是任何帮助都将不胜感激.

I would like to use a system fact for a host times a number/percentage as a base for a variable. What I am trying to do specifically is use the ansible_memtotal_mb value and multiply it by .80 to get a ramsize to then use in setting a Couchbase value. I have been trying different variations of the line below. I'm not ever sure that it is possible, but any help would be appreciated.

vars:
  ramsize: '"{{ ansible_memtotal_mb }}" * .80'

推荐答案

您真的很亲密！我使用计算来设置一些默认的Java内存大小，这与您正在执行的操作类似.这是一个示例:

You're really close! I use calculations to set some default java memory sizes, which is similar to what you are doing. Here's an example:

{{ (ansible_memtotal_mb*0.8-700)|int|abs }}

这说明了两件事-首先，它使用 jinja数学 ，{{ jinja }}内部的计算也是如此.其次，int和abs执行您所期望的操作-确保结果是无符号整数.

That shows a couple of things- first, it's using jinja math, so do the calculations inside the {{ jinja }}. Second, int and abs do what you'd expect- ensure the result is an unsigned integer.

您的情况下，正确的代码应为:

In your case, the correct code would be:

vars:
  ramsize: "{{ ansible_memtotal_mb * 0.8 }}"

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