https://stackoverflow.com/questions/77619055/access-unreachable-nodes-sections-via-awk-command

Session.txt

$ tree .
.
├── demo.yml
├── unreachable_nodes-1.yml
└── unreachable_nodes-2.yml

0 directories, 3 files

$ cat unreachable_nodes-1.yml 
---
unreachable_nodes:
  - hostname: host098
    ip: host098
  - hostname: host099
    ip: host099


$ cat unreachable_nodes-2.yml 
---
unreachable_nodes:
  - hostname: host098
    ip: host098
  - hostname: host100
    ip: host100


$ cat demo.yml 
---
- hosts: localhost
  gather_facts: false

  tasks:
    - name: Load data from first server
      ansible.builtin.include_vars:
        file: unreachable_nodes-1.yml
        name: data_A

    - name: Load data from second server
      ansible.builtin.include_vars:
        file: unreachable_nodes-2.yml
        name: data_B

    - name: Show entries present in both list
      ansible.builtin.debug:
        var: data_A.unreachable_nodes | intersect(data_B.unreachable_nodes)

    - name: Show entries present only in A or B
      ansible.builtin.debug:
        var: data_A.unreachable_nodes | symmetric_difference(data_B.unreachable_nodes)
    
    - name: Show entries present in A but not in B
      ansible.builtin.debug:
        var: data_A.unreachable_nodes | difference(data_B.unreachable_nodes)
    
    - name: Show entries present in B but not in A
      ansible.builtin.debug:
        var: data_B.unreachable_nodes | difference(data_A.unreachable_nodes)

    - name: Show entries present in either files
      ansible.builtin.debug:
        var: data_A.unreachable_nodes | union(data_B.unreachable_nodes)

$ ansible-playbook demo.yml 

PLAY [localhost] *********************************************************************************************************************************

TASK [Load data from first server] ***************************************************************************************************************
ok: [localhost]

TASK [Load data from second server] **************************************************************************************************************
ok: [localhost]

TASK [Show entries present in both list] *********************************************************************************************************
ok: [localhost] => {
    "data_A.unreachable_nodes | intersect(data_B.unreachable_nodes)": [
        {
            "hostname": "host098",
            "ip": "host098"
        }
    ]
}

TASK [Show entries present only in A or B] *******************************************************************************************************
ok: [localhost] => {
    "data_A.unreachable_nodes | symmetric_difference(data_B.unreachable_nodes)": [
        {
            "hostname": "host099",
            "ip": "host099"
        },
        {
            "hostname": "host100",
            "ip": "host100"
        }
    ]
}

TASK [Show entries present in A but not in B] ****************************************************************************************************
ok: [localhost] => {
    "data_A.unreachable_nodes | difference(data_B.unreachable_nodes)": [
        {
            "hostname": "host099",
            "ip": "host099"
        }
    ]
}

TASK [Show entries present in B but not in A] ****************************************************************************************************
ok: [localhost] => {
    "data_B.unreachable_nodes | difference(data_A.unreachable_nodes)": [
        {
            "hostname": "host100",
            "ip": "host100"
        }
    ]
}

TASK [Show entries present in either files] ******************************************************************************************************
ok: [localhost] => {
    "data_A.unreachable_nodes | union(data_B.unreachable_nodes)": [
        {
            "hostname": "host098",
            "ip": "host098"
        },
        {
            "hostname": "host099",
            "ip": "host099"
        },
        {
            "hostname": "host100",
            "ip": "host100"
        }
    ]
}

PLAY RECAP ***************************************************************************************************************************************
localhost                  : ok=7    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0