Getting attribute value using Ansible filters

Question

I am trying to get my attribute value from JSON data.

Here is my JSON data:

{
   "user1": "{\n \"data\":[\n    {\n     \"secure\": [\n       {\n              \"key\": \"-----BEGIN  KEY-----\nMIIEowIBAAKCAQEAgOh+Afb0oQEnvHifHuzBwhCP3\n-----END KEY-----\"\n       }\n      ],\n     \"owner\": \"shallake\",\n     \"position\": \"gl\"\n    }\n   ]\n}"
}

Initially, I had invalid JSON data, so I converted it into valid JSON using to_json and from_json. The above JSON data is the result that I get.

code:

 - set_fact:
      user: "{{ lookup('file','filepath/myfile.json') | to_json }}"

 - set_fact:
      user1: "{{ user | from_json}}"

 - set_fact:
      user3: "{{ item }}"
   with_items: "{{ user1['data'] | map(attribute='position') | list }}"

In a third set_fact, I am trying to get position attribute value. But it shows an error like this:

the field 'args' has an invalid value, which appears to include a variable that is undefined. The error was: 'item' is undefined

"\"{\n \\"data\\":[\n {\n \\"secure\\": [\n {\n \\"key\\": \\"-----BEGINPRIVATE KEY-----\nMIIEowIBAAKCAQEAgOh+Afb0oQEnvHifHuzBwl+Tiu8LXoJXb/ii/eh\ngYEP3\n-----END PRIVATE KEY-----\\"\n }\n ],\n \\"owner\\": \\"shalloke\\",\n \\"position\\": \\"gl\\"\n }\n ]\n}\n\n\""

So how can I get a position value from the above JSON data result using Ansible loop?

Answer 1

Would you please check if the key in filepath/myfile.json spans multiple lines? We need to escape line breaks in JSON. Use \n to replace line breaks.

The user1 is supported to be a map parsed from JSON. However, the JSON in filepath/myfile.json might be invalid. So in the second set_fact, this invalid JSON couldn't be parsed. Thus, user1 is just a string. And it doesn't contain an entry data.

{
  "data":[
      {
      "secure": [
        {
                "key": "-----BEGIN  KEY-----\nMIIEowIBAAKCAQEAgOh+Afb0oQEnvHifHuzBwhCP3\n-----END KEY-----"
        }
        ],
      "owner": "shallake",
      "position": "gl"
      }
    ]
}

How do I handle newlines in JSON?

Answer 2

You should use either from_json (not to_json) filter, or not use filter at all, when importing file in a JSON format into an Ansible dictionary.

I point out the mistake below, but first a working example:

• myfile.json:

  {
    "data": [
      {
        "secure": [
          {
            "key": "-----BEGIN  KEY-----\nMIIEowIBAAKCAQEAgOh+Afb0oQEnvHifHuzBwhCP3\n-----END KEY-----"
          }
        ],
        "owner": "shallake",
        "position": "gl"
      }
    ]
  }
  

• Playbook:

  ---
  - hosts: localhost
    gather_facts: no
    connection: local
    tasks:
      - set_fact:
          data_from_json: "{{ lookup('file','./myfile.json') | from_json }}"
  
      - set_fact:
          position: "{{ item }}"
        with_items: "{{ data_from_json['data'] | map(attribute='position') | list }}"
  
      - name: Display extracted position
        debug:
          var: position
  

• The result (relevant task only):

  TASK [Display extracted position] *********************************************************************************************************
  ok: [localhost] => {
      "position": "gl"
  }
  

---

Now your mistake:

Your myfile.json is not a correct JSON file.

You seemingly looked at the log of Ansible and copied it from the screen to the file. As you already saw, it will not be a valid JSON format (it will contain escaped quotes and newline characters which will prevent importing it).

If you want to copy the Ansible dictionary into a file, you can do it using the following task (I'm assuming here data is in the data_from_json variable, like at the end of my example playbook above):

- local_action: copy content={{ data_from_json | to_nice_json }} dest=./myfile2.json

to_nice_json is optional here, but it will produce very similar to the output as the myfile.json above (the order of keys might change and the indentation).