同一剧本中主机之间的 Ansible 传递事实

Question

我正在尝试将事实从 host1 传递到 host2，但是当 ansible 到达 host2 时它说“未定义的变量”

代码：

- name: some playbook
  gather_facts: no
  hosts: host1
  tasks:

    - set_fact:
        fact1: "foo"

- hosts: host2
  gather_facts: no
  tasks:

    - debug:
        msg: "{{ fact1 }}"

Answer 1

set_fact 模块设置主机变量，您可以使用 hostvars.

访问这些变量

- name: some playbook
  gather_facts: no
  hosts: host1
  tasks:

  - set_fact:
      fact1: "foo"

- hosts: host2
  gather_facts: no
  tasks:

  - debug:
      msg: "{{ hostvars['host1']['fact1'] }}"

Answer 2

一般来说，这个用例可以分三步解决。创建、共享和使用变量。例如，给定库存

shell> cat hosts
host1
host2

剧本按预期工作

- name: Run single host and create facts
  hosts: host1
  tasks:
    - set_fact:
        fact1: foo

- name: Share facts among all hosts
  hosts: all
  tasks:
    - set_fact:
        fact1: "{{ hostvars.host1.fact1 }}"
      run_once: true

- name: Use shared facts
  hosts: host2
  tasks:
    - debug:
        var: fact1

如果将用例扩展为“将事实从一组主机传递到另一组主机”，问题是如何有效地共享变量？动态创建剧本。例如，给定库存

shell> cat hosts
host1
host2
host3
host4

让 host1 和 host4 创建变量，host2 和 host3 使用它们。创建模板

shell> cat share-vars.yml.j2
- name: Share facts among all hosts
  hosts: all
  tasks:
    - set_fact:
{% for i in share_vars %}
        {{ i.var }}: "{{ lbr }} hostvars.{{ i.host }}.{{ i.var }} {{ rbr }}"
{% endfor %}
      run_once: true

和剧本

shell> cat create-share-vars.yml
- name: Create playbook share-vars.yml
  hosts: localhost
  vars:
    share_vars:
      - {host: host1, var: fact1}
      - {host: host4, var: fact4}
    lbr: "{{ '{{' }}"
    rbr: "{{ '}}' }}"
  tasks:
    - template:
        src: share-vars.yml.j2
        dest: share-vars.yml

给予

shell> cat share-vars.yml
- name: Share facts among all hosts
  hosts: all
  tasks:
    - set_fact:
        fact1: "{{ hostvars.host1.fact1 }}"
        fact4: "{{ hostvars.host4.fact4 }}"
      run_once: true

例如导入此剧本

shell> cat playbook.yml
- hosts: host1
  tasks:
    - set_fact:
        fact1: foo

- hosts: host4
  tasks:
    - set_fact:
        fact4: bar

- import_playbook: share-vars.yml

- hosts: host2,host3
  tasks:
    - debug:
        var: fact1
    - debug:
        var: fact4

给出（删节）

PLAY [host2,host3] *********************************************************

TASK [debug] ***************************************************************
ok: [host2] => 
  fact1: foo
ok: [host3] => 
  fact1: foo

TASK [debug] ***************************************************************
ok: [host2] => 
  fact4: bar
ok: [host3] => 
  fact4: bar

备注

模板的优势是什么？更改变量 share_vars 并在需要时重建导入的游戏。不要更改代码。
在 Ansible 中，不可能替换赋值的左侧，即没有 symbolic reference.
如果不需要，请将“gather_facts: false”添加到 plays 中。

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