Ansible：如何编写以服务为中心的清单？

Ansible通常以主机为中心工作：如果您的主机在资源清册中的多个组中包含某些主机变量，则该主机的所有变量都将合并，并且具有相同名称的变量将相互覆盖。例如：

# Inventory

[app_stages:children]
stage_development
stage_acceptance

[stage_development]
localhost db_unique_name=scdev oracle_version_db=12.1.0.2 oracle_edition_db=SE2
localhost db_unique_name=ecdev oracle_version_db=12.1.0.2 oracle_edition_db=EE

[stage_acceptance]
localhost db_unique_name=scacp oracle_version_db=18 oracle_edition_db=SE2
localhost db_unique_name=ecacp oracle_version_db=18 oracle_edition_db=EE

结果:

   ansible-playbook playbook_1.yml -i inventory_1 -e hostgroup=stage_development

   TASK [show variables]  ******************************************************************************************************************
   ok: [localhost] => {
       "msg": "host server_1, db_name = ecacp, db_version = 18, db_edition = EE"
   }

这表明，即使我请求ansible进行stage_开发，它也只使用并显示在其他组中设置的变量

我需要一种不同的方法：首先，我希望使用一些基本参数指定服务，例如数据库名称、版本等，请参见上文。是否将部分或全部部署到同一主机是次要的。这一个工作，但不是那么优雅，因为有关服务的信息在剧本中，而不是在库存中，应该由一些外部工具CMS稍后生成：

# Inventory
[app_stages:children]
stage_development
stage_acceptance

[stage_development:children]
srv_scdev
srv_ecdev

[stage_acceptance:children]
srv_scacp
srv_ecacp

[srv_scdev]
localhost

[srv_ecdev]
localhost

[srv_scacp]
localhost

[srv_ecacp]
localhost

---

问题：如何做到正确/可重复使用/优雅？

一个变化最小的解决方案是通过设置ansible_主机来扩展您的库存，并为库存本身引入一个假名称，如

# Inventory

[app_stages:children]
stage_development
stage_acceptance

[stage_development]
dev1 ansible_host=localhost db_unique_name=scdev oracle_version_db=12.1.0.2 oracle_edition_db=SE2
dev2 ansible_host=localhost db_unique_name=ecdev oracle_version_db=12.1.0.2 oracle_edition_db=EE

[stage_acceptance]
stage1 ansible_host=localhost db_unique_name=scacp oracle_version_db=18 oracle_edition_db=SE2
stage2 ansible_host=localhost db_unique_name=ecacp oracle_version_db=18 oracle_edition_db=EE

# Playbook
---

- name: stage development, setup database scdev
  hosts: srv_scdev
  vars:
    db_unique_name: scdev
    oracle_version_db: 12.1.0.2
    oracle_edition_db: SE2
  tasks:
    - name: show variables
      debug:
        msg: host {{ ansible_hostname }}, db_name = {{ db_unique_name }}, db_version = {{ oracle_version_db }}, db_edition = {{ oracle_edition_db }}

- name: stage development, setup database ecdev
  hosts: srv_ecdev
  vars:
    db_unique_name: ecdev
    oracle_version_db: 12.1.0.2
    oracle_edition_db: EE
  tasks:
    - name: show variables
      debug:
        msg: host {{ ansible_hostname }}, db_name = {{ db_unique_name }}, db_version = {{ oracle_version_db }}, db_edition = {{ oracle_edition_db }}

- name: stage acceptance, setup database scacp
  hosts: srv_scacp
  vars:
    db_unique_name: scacp
    oracle_version_db: 18
    oracle_edition_db: SE2
  tasks:
    - name: show variables
      debug:
        msg: host {{ ansible_hostname }}, db_name = {{ db_unique_name }}, db_version = {{ oracle_version_db }}, db_edition = {{ oracle_edition_db }}

- name: stage acceptance, setup database ecacp
  hosts: srv_ecacp
  vars:
    db_unique_name: ecacp
    oracle_version_db: 18
    oracle_edition_db: EE
  tasks:
    - name: show variables
      debug:
        msg: host {{ ansible_hostname }}, db_name = {{ db_unique_name }}, db_version = {{ oracle_version_db }}, db_edition = {{ oracle_edition_db }}

...

# Inventory

[app_stages:children]
stage_development
stage_acceptance

[stage_development]
dev1 ansible_host=localhost db_unique_name=scdev oracle_version_db=12.1.0.2 oracle_edition_db=SE2
dev2 ansible_host=localhost db_unique_name=ecdev oracle_version_db=12.1.0.2 oracle_edition_db=EE

[stage_acceptance]
stage1 ansible_host=localhost db_unique_name=scacp oracle_version_db=18 oracle_edition_db=SE2
stage2 ansible_host=localhost db_unique_name=ecacp oracle_version_db=18 oracle_edition_db=EE