如何在Ansible中高效访问嵌套JSON对象？附Nautobot实操场景

我有如下JSON结构，能访问到二级层级，但无法深入到destination_services这类嵌套列表的下层，点语法无效，推测是列表、字典混合结构导致的。

原始JSON片段：

"json": {
    "count": 5,
    "next": null,
    "previous": null,
    "results": [
        {
            "action": "pass",
            "application_groups": [],
            "applications": [],
            "created": "2024-06-20T09:53:20.139779+02:00",
            "custom_fields": {},
            "description": "",
            "destination_address_groups": [],
            "destination_addresses": [],
            "destination_service_groups": [],
            "destination_services": [
                {
                    "created": "2024-06-18T02:00:00+02:00",
                    "custom_fields": {},
                    "description": "",
                    "display": "ICMP (ICMP)",
                    "id": "c52f9be9-b4ca-4dd4-8993-2615c2fe004f",
                    "ip_protocol": "ICMP",
                    "last_updated": "2024-06-18T10:52:44.698368+02:00",
                    "name": "ICMP",
                    "natural_slug": "icmp__icmp_c52f"
                }
            ]
        }
    ]
}

我执行的Ansible任务：

- name: API CALL (Nautobot GET rules)
  ansible.builtin.uri:
    url: https://{{ nautobot_ip }}/api/plugins/firewall/policy-rule/?depth=4
    method: GET
    validate_certs: false
    headers:
      Authorization: Token {{ nautobot_token }}
  register: firewall_rules

- name: SET FACT (Firewall policy rules)
  ansible.builtin.set_fact:
    firewall_policy_rules: "{{ firewall_rules['json']['results'] | json_query('[].{ dst_services: destination_services, dst_services_names: destination_services.names } ') }}"

我的目标是创建可用于后续任务的完整防火墙规则映射字典，部分对象层级比destination_services更深。期望得到如下格式的结果（同时保留完整的destination_services列表和提取出的name属性）：

"ansible_facts": {
    "firewall_policy_rules": [
        {
            "destination_services": [
                {
                    "created": "2024-06-18T02:00:00+02:00",
                    "custom_fields": {},
                    "description": "",
                    "display": "ICMP (ICMP)",
                    "id": "c52f9be9-b4ca-4dd4-8993-2615c2fe004f",
                    "ip_protocol": "ICMP",
                    "last_updated": "2024-06-18T10:52:44.698368+02:00",
                    "name": "ICMP",
                    "natural_slug": "icmp__icmp_c52f"
                }
            ],
            "dst_services_names": "ICMP"
        }
    ]
}

1. 修正JSON Query语法 #

问题出在destination_services.names的写法上：destination_services是列表类型，不能直接用点语法访问内部属性，必须先遍历列表元素（用[*]）。

根据你的需求，分两种情况处理：

• 如果每个规则的destination_services只有一个元素，直接取第一个元素的name：

  - name: SET FACT (Firewall policy rules)
    ansible.builtin.set_fact:
      firewall_policy_rules: "{{ firewall_rules['json']['results'] | json_query('[].{ destination_services: destination_services, dst_services_names: destination_services[0].name } ') }}"
  

• 如果可能有多个服务，需要将所有name拼接成字符串（用join(', ')）：

  - name: SET FACT (Firewall policy rules)
    ansible.builtin.set_fact:
      firewall_policy_rules: "{{ firewall_rules['json']['results'] | json_query('[].{ destination_services: destination_services, dst_services_names: destination_services[*].name | join(\", \") } ') }}"
  

2. 处理更深层级的嵌套结构 #

如果有更复杂的多层嵌套（比如destination_services里还有子列表/字典），可以继续用[*]遍历，或者结合Ansible的其他过滤器（比如map、flatten）：
例如要提取destination_services下所有子元素的ip_protocol：

- name: Extract deep nested values
  ansible.builtin.set_fact:
    service_protocols: "{{ firewall_rules['json']['results'] | json_query('[].destination_services[*].ip_protocol') | flatten }}"

3. 保留完整结构并扩展属性 #

如果需要保留原规则的所有字段，同时添加提取的属性，不需要重新构造整个字典，直接用combine过滤器：

- name: Add extracted fields to original rules
  ansible.builtin.set_fact:
    firewall_policy_rules: "{{ firewall_rules['json']['results'] | map('combine', {'dst_services_names': item.destination_services | map(attribute='name') | join(', ')}) | list }}"
  loop: "{{ firewall_rules['json']['results'] }}"

内容的提问来源于stack exchange，提问作者kuda