访问其他主机的字典变量

好吧，您已经很接近解决方案了，因为它hostvars[hosta].rproxyitems肯定表明您在正确的轨道上。
但是，由于pageA.com和pageB.com是列表的值而不是键或字典的值，因此这使您的任务更加复杂。

针对您的问题的两种解决方案：

1. 通过实际的列表结构，您可以使用Jinja过滤器select和matchAnsible的测试来匹配列表中具有以下特定元素的元素rproxyfqdn：rproxyitems | selectattr('rproxyfqdn', 'match', 'pageA.com')。这将返回一个列表，因此，如果您确定始终只有一个匹配项，则只需添加first过滤器即可。
   鉴于剧本

   - hosts: hostb
     gather_facts: no
   
     tasks:
       - debug:
           msg: "{{ nginxvhost }}"
         vars:
           nginxvhost:
             - fqdn: pageA.com
               servername: "{{ (hostvars['hosta'].rproxyitems | selectattr('rproxyfqdn', 'match', 'pageA.com') | first).rproxytarget }}"
               serveraltname: "{{ (hostvars['hosta'].rproxyitems | selectattr('rproxyfqdn', 'match', 'pageA.com') | first).rproxyaltfqdn }}"
               comment: "This is website A target webservice"
             - fqdn: pageB.com
               servername: "{{ (hostvars['hosta'].rproxyitems | selectattr('rproxyfqdn', 'match', 'pageB.com') | first).rproxytarget }}"
               serveraltname: "{{ (hostvars['hosta'].rproxyitems | selectattr('rproxyfqdn', 'match', 'pageB.com') | first).rproxyaltfqdn }}"
               comment: "This is website B target webservice"
   

   总结一下：

   PLAY [hostb] *****************************************************************************************************
   
   TASK [debug] *****************************************************************************************************
   ok: [hostb] => {
       "msg": [
           {
               "comment": "This is website A target webservice",
               "fqdn": "pageA.com",
               "serveraltname": "alternativeA1.com alternativeA2.com",
               "servername": "http://destinationA"
           },
           {
               "comment": "This is website B target webservice",
               "fqdn": "pageB.com",
               "serveraltname": "alternativeB1.com alternativeBb.com",
               "servername": "http://destinationB"
           }
       ]
   }
   
   PLAY RECAP *******************************************************************************************************
   hostb                      : ok=1    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
   

2. 您还可以稍微更改数据结构，并使用字典而不是列表，从而更轻松地访问特定条目：

   rproxyitems:
     pageA.com:
       comment: "This ia website A"
       rproxyaltfqdn: "alternativeA1.com alternativeA2.com"
       rproxytarget: "http://destinationA"
     pageB.com:
       comment: "This ia website B"
       rproxyaltfqdn: "alternativeB1.com alternativeBb.com"
       rproxytarget: "http://destinationB"
   

   这使我们可以直接访问rproxyitems['pageA.com']并简化剧本：

   - hosts: hostb
     gather_facts: no
   
     tasks:
       - debug:
           msg: "{{ nginxvhost }}"
         vars:
           nginxvhost:
             - fqdn: pageA.com
               servername: "{{ hostvars['hosta'].rproxyitems['pageA.com'].rproxytarget }}"
               serveraltname: "{{ hostvars['hosta'].rproxyitems['pageA.com'].rproxyaltfqdn }}"
               comment: "This is website A target webservice"
             - fqdn: pageB.com
               servername: "{{ hostvars['hosta'].rproxyitems['pageB.com'].rproxytarget }}"
               serveraltname: "{{ hostvars['hosta'].rproxyitems['pageB.com'].rproxyaltfqdn }}"
               comment: "This is website B target webservice"
   

   这将给出与上述相同的概述。