JMESPath在查询中的使用

Question

我使用以下JSON文件：

sample.json

{
    "lldp_output['gathered']": [
        {
            "mode": "trunk",
            "name": "GigabitEthernet0/0",
            "trunk": {
                "encapsulation": "dot1q"
            }
        },
        {
            "access": {
                "vlan": 12
            },
            "mode": "access",
            "name": "GigabitEthernet0/1"
        },
        {
            "name": "GigabitEthernet0/2"
        }
    ]
}

还有剧本：

---
- hosts: localhost
  gather_facts: no
  vars:
    tmpdata: "{{ lookup('file','sample.json') | from_json }}"

  tasks:
    - name: Take 4
      debug:
        msg: "{{ tmpdata | community.general.json_query(lldp_output['gathered']) }}"

我得到以下错误：

TASK [Take 4] ********************************************************************************************
task path: /root/scripts/atest.yml:18
fatal: [localhost]: FAILED! => {
    "msg": "Error in jmespath.search in json_query filter plugin:\n'lldp_output' is undefined"
}

如何查询显示的JSON，以便获得所有具有mode: trunk的端口的列表

当我在一本剧本里奔跑时：

---
- name: Find trunk ports
  hosts: ios

  tasks:
    - name: Collect interface output
      cisco.ios.ios_l2_interfaces:
        config:
        state: gathered
      register:
         "intf_output"

    - debug:
        var=intf_output

    - name: Take 4
      debug:
        msg: "{{ intf_output | json_query(query) }}"
      vars:
        query: >-
          "lldp_output['gathered']"[?mode=='trunk']

返回的结构如下：

{
    "intf_output": {
        "ansible_facts": {
            "discovered_interpreter_python": "/usr/bin/python3"
        },
        "changed": false,
        "failed": false,
        "gathered": [
            {
                "name": "GigabitEthernet0/0"
            },
            {
                "mode": "trunk",
                "name": "GigabitEthernet0/1",
                "trunk": {
                    "allowed_vlans": [
                        "10",
                        "20",
                        "30",
                        "100"
                    ],
                    "encapsulation": "dot1q"
                }
            },
            {
                "mode": "trunk",
                "name": "GigabitEthernet0/2",
                "trunk": {
                    "allowed_vlans": [
                        "10",
                        "20",
                        "30",
                        "100"
                    ],
                    "encapsulation": "dot1q"
                }
            },
            {
                "mode": "trunk",
                "name": "GigabitEthernet0/3",
                "trunk": {
                    "allowed_vlans": [
                        "10",
                        "20",
                        "30",
                        "100"
                    ],
                    "encapsulation": "dot1q"
                }
            },
            {
                "mode": "trunk",
                "name": "GigabitEthernet1/0",
                "trunk": {
                    "allowed_vlans": [
                        "10",
                        "20",
                        "30",
                        "100"
                    ],
                    "encapsulation": "dot1q"
                }
            },
            {
                "mode": "trunk",
                "name": "GigabitEthernet1/1",
                "trunk": {
                    "allowed_vlans": [
                        "10",
                        "20",
                        "30",
                        "100"
                    ],
                    "encapsulation": "dot1q"
                }
            },
            {
                "name": "GigabitEthernet1/2"
            },
            {
                "name": "GigabitEthernet1/3"
            },
            {
                "name": "GigabitEthernet2/0"
            },
            {
                "name": "GigabitEthernet2/1"
            },
            {
                "name": "GigabitEthernet2/2"
            },
            {
                "name": "GigabitEthernet2/3"
            },
            {
                "name": "GigabitEthernet3/0"
            },
            {
                "name": "GigabitEthernet3/1"
            },
            {
                "name": "GigabitEthernet3/2"
            },
            {
                "name": "GigabitEthernet3/3"
            }
        ]
    }
}

对于每一位主人，我都会与剧本相冲突。

Answer 1

json_query的参数必须是字符串。因为您没有引用您的论点，Ansible正在寻找一个名为lldp_output的变量。但是您有附加的问题，因为您试图访问一个名为lldp_output['gathered']的键，但是[在JSON (和JMESPath查询)中是一个语法上重要的字符，所以也需要转义。

为了避免所有类型的引号转义扭曲，我们可以将查询本身放入一个变量中，这样我们就可以：

- hosts: localhost
  vars:
    tmpdata: "{{ lookup('file','sample.json') | from_json }}"

  tasks:
    - name: Take 4
      debug:
        msg: "{{ tmpdata | json_query(query) }}"
      vars:
        query: >-
          "lldp_output['gathered']"

注意，我们使用的是>-块引号操作符，这意味着query的值是文字字符串"lldp_output['gathered']"，包括外部引号。

该剧本输出如下：

TASK [Take 4] *********************************************************************************
ok: [localhost] => {
    "msg": [
        {
            "mode": "trunk",
            "name": "GigabitEthernet0/0",
            "trunk": {
                "encapsulation": "dot1q"
            }
        },
        {
            "access": {
                "vlan": 12
            },
            "mode": "access",
            "name": "GigabitEthernet0/1"
        },
        {
            "name": "GigabitEthernet0/2"
        }
    ]
}

要获得那些mode等于trunk的系统，只需将该条件添加到查询中：

- hosts: localhost
  vars:
    tmpdata: "{{ lookup('file','sample.json') | from_json }}"

  tasks:
    - name: Take 4
      debug:
        msg: "{{ tmpdata | json_query(query) }}"
      vars:
        query: >-
          "lldp_output['gathered']"[?mode=='trunk']

这将产生以下结果：

TASK [Take 4] *********************************************************************************
ok: [localhost] => {
    "msg": [
        {
            "mode": "trunk",
            "name": "GigabitEthernet0/0",
            "trunk": {
                "encapsulation": "dot1q"
            }
        }
    ]
}

更新

考虑到您在更新的问题中显示的数据，情况要简单得多，因为您没有原始问题中的奇怪引用。使用如图所示的intf_output定义，您可以编写：

  tasks:
    - name: Take 4
      debug:
        msg: "{{ intf_output | json_query(query) }}"
      vars:
        query: >-
          gathered[?mode=='trunk']