在Ansible中创建动态列表的正确方法 [英] Correct way to create dynamic lists in Ansible

问题描述

我正在寻找建议.我有以下代码可以动态创建一个列表，以后可以在模板中使用它.

I'm looking for advice. I have the following code that creates a list dynamically that I can then later use in a template.

这是我编写的测试代码的副本-对于实际角色，我只是将admins | regex_replace变量添加到j2模板中.

This is a copy of the test code I put together - for the actual role I just added the admins|regex_replace variable into the j2 template.

    ---

  - hosts: localhost
    gather_facts: false

    vars:
      # define empty admins var first so ansible doesn't complain
      admins:

      admin_accounts:
      - name: john
        uid: 1000
        group: sysadmin
        shell: /bin/bash
        comment: "Unix Administrator"
      - name: paul
        uid: 1001
        group: sysadmin
        shell: /bin/bash
        comment: "Unix Administrator"
      - name: george
        uid: 1002
        group: sysadmin
        shell: /bin/bash
        comment: "Unix Administrator"
      - name: ringo
        uid: 1003
        group: sysadmin
        shell: /bin/bash
        comment: "Unix Administrator"

    tasks:

      - name: build array of admin user names
        set_fact: admins="{{ admins}} {{ item.name }}"
        with_items: "{{ admin_accounts }}"

      # print out the fact piping through two jinja2 filters
      # careful with word wrapping
      - debug: msg={{ admins | regex_replace( '\s+',', ' ) | regex_replace`(',\s(.*)','\\1') }}`

这给了我以下内容:

    PLAY [localhost] ***************************************************************

TASK [build array of admin user names] *****************************************
ok: [localhost] => (item={u'comment': u'Unix Administrator', u'shell': u'/bin/bash', u'group': u'sysadmin', u'name': u'john', u'uid': 1000})
ok: [localhost] => (item={u'comment': u'Unix Administrator', u'shell': u'/bin/bash', u'group': u'sysadmin', u'name': u'paul', u'uid': 1001})
ok: [localhost] => (item={u'comment': u'Unix Administrator', u'shell': u'/bin/bash', u'group': u'sysadmin', u'name': u'george', u'uid': 1002})
ok: [localhost] => (item={u'comment': u'Unix Administrator', u'shell': u'/bin/bash', u'group': u'sysadmin', u'name': u'ringo', u'uid': 1003})

TASK [debug] *******************************************************************
ok: [localhost] => {
    "msg": "john, paul, george, ringo"
}

PLAY RECAP *********************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0

所以...我得到了我所需要的，但是我是否正以正确的方式去做?

So...I get what I need, but am I going about it the right way?

Ansible版本是在Centos 7.2上运行的2.0.2.0.

Ansible version is 2.0.2.0 running on Centos 7.2.

谢谢.

最终的过滤器最终看起来像这样:

The resultant filter ended up looking like this:

  - name: build list of admin user names
    set_fact:
      admin_list: "{{ admin_accounts | selectattr('state', 'equalto', 'present') | map(attribute='name') | join(', ') }}"
  - debug: msg={{ admin_list }}

已向Yaml添加了另一个参数:

Having added another parameter to the yaml:

state: absent

Ringo根据需要被排除在外.

Ringo was left out, as desired.

推荐答案

过滤器将对列表进行操作，因此with_items确实很浪费，而regex东西对于您正在做的事情相当晦涩.您是否真的要用逗号分隔的字符串，还是只需要从admin_accounts列表中提取的用户名列表?

Filters will operate on lists, so the with_items is really wasteful, and the regex stuff is pretty obtuse for what you're doing. Do you really want a comma-separated string, or do you just want a list of the usernames extracted from the admin_accounts list?

如果您只想要列表，为什么不呢?

If you just want the list, why not:

set_fact:
  admin_usernames: "{{ admin_accounts | map(attribute='name') | list }}"

...，如果您确实希望将逗号分隔的列表作为纯字符串，只需添加一个连接过滤器即可:

... and if you really want the comma-separated list as a flat string, just add a join filter:

set_fact:
  admin_usernames: "{{ admin_accounts | map(attribute='name') | join(', ') }}"

但是，如果最终目标是模板，则建议在模板内执行此操作，因为这看起来与格式相关，而与逻辑相关(除非您只是出于堆栈溢出的目的而简化).

If your ultimate target is a template, though, I'd suggest doing this inside the template, since this looks pretty formatting-related as opposed to logic-related (unless you're just simplifying for Stack Overflow purposes)...

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