how to deal with missing keys in JSON array when reading in Ansible

Question

Below is my JSON file:

[
  {
    "?xml": {
      "attributes": {
        "encoding": "UTF-8",
        "version": "1.0"
      }
    }
  },
  {
    "domain": [
      {
        "name": "mydom"
      },
      {
        "domain-version": "12.2.1.3.0"
      },
      {
        "server": [
          {
            "name": "AdminServer"
          },
          {
            "ssl": {
              "name": "AdminServer"
            }
          },
          {
            "listen-port": "12400"
          },
          {
            "listen-address": "mydom.host1.bank.com"
          }
        ]
      },
      {
        "server": [
          {
            "name": "myserv1"
          },
          {
            "ssl": [
              {
                "name": "myserv1"
              },
              {
                "login-timeout-millis": "25000"
              }
            ]
          },
          {
            "log": [
              {
                "name": "myserv1"
              },
              {
                "file-name": "/web/bea_logs/domains/mydom/myserv1/myserv1.log"
              }
            ]
          }
        ]
      },
      {
        "server": [
          {
            "name": "myserv2"
          },
          {
            "ssl": {
              "name": "myserv2"
            }
          },
         {
           "reverse-dns-allowed": "false"
         },
          {
            "log": [
              {
                "name": "myserv2"
              },
              {
                "file-name": "/web/bea_logs/domains/mydom/myserv2/myserv2.log"
              }
            ]
          }
        ]
      }
    ]
  }
]

I need to get log list's name and file-name like below using ansible code.

myserv1_log: "/web/bea_logs/domains/mydom/myserv1/myserv1.log"
myserv2_log: "/web/bea_logs/domains/mydom/myserv2/myserv2.log"

There are two challenges that i m facing.

1. server may not always be the 3rd key of domain array.
2. log array may not alway be a key for all server arrays and thus should not be printed. For example. server name AdminServer does not have any log list while myserv1 & myserv2 do have.

I need an ansible code to print the desired for the dynamically changing json.

Note: server will always be a key in the domain array

I'm posting with reference to my similar query here: unable to ideally parse a json file in ansible

Kindly suggest.

Answer 1

you just test if both keys exist:

- hosts: localhost
  gather_facts: no
  vars:
    json: "{{ lookup('file', './file.json') | from_json }}"
  tasks:
    - name: display
      debug:
        msg: "name: {{ servername }} --> filename: {{ filename }}"
      loop: "{{ json[1].domain }}"
      vars:
        servername: "{{ item.server.0.name }}_log"
        filename: "{{ item['server'][2]['log'][1]['file-name'] }}"
      when: item.server is defined and item.server.2.log is defined

result:

TASK [display] 
skipping: [localhost] => (item={'name': 'USWL1212MRSHM01'}) 
skipping: [localhost] => (item={'domain-version': '12.2.1.3.0'}) 
skipping: [localhost] => (item={'server': [{'name': 'AdminServer'}, {'ssl': {'name': 'AdminServer'}}, {'listen-port': '12400'}, {'listen-address': 'myhost1'}]}) 
ok: [localhost] => (item={'server': [{'name': 'myserv1'}, {'ssl': {'name': 'myserv1'}}, {'log': [{'name': 'myserv1'}, {'file-name': '/web/bea_logs/domains/mydom/myserv1/myserv1.log'}]}]}) => {
    "msg": "name: myserv1_log --> filename: /web/bea_logs/domains/mydom/myserv1/myserv1.log"
}
ok: [localhost] => (item={'server': [{'name': 'myserv2'}, {'ssl': {'name': 'myserv2'}}, {'log': [{'name': 'myserv2'}, {'file-name': '/web/bea_logs/domains/mydom/myserv2/myserv2.log'}]}]}) => {
    "msg": "name: myserv2_log --> filename: /web/bea_logs/domains/mydom/myserv2/myserv2.log"
}

As you can see, when the condition is not true, the action is skipped...

you could simplify by testing only key log, because in your case, keylog is always linked to key server

when: item.server.2.log is defined