Create Json file using Jinja2 template in ansible

Question

I want to create dynamic json file depend upon data available. Suppose I have data like below. then jinja template should create 2 list. if data available 3 time then it should create 3 list in jinja template.

"datastore_details": [
            {
                "name": "XYZ",
                "size": 6258
            },
            {
                "name": "XYZ-1",
                "size": 32192
            }
 
        ]

 

{
    "company": "Test",
    "table": "data",
    "message_id": "2022222",
    "p_filter": {
        "key": "u_topic",
        "value": "test-datastore"
    },
    "c_filter": {
        "key": "u_topic",
        "value": "test-disk_capacity"
    },
    "p_data": [        
        {
          
            "u_label": "XYZ",
            "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
            "u_value": "XYZ",
            "c_data": [
                {
                    "u_label": "XYZ",
                    "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
                    "u_value": "6258"
                }
            ]
        },
        {
            "u_label": "XYZ-1",
            "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
            "u_value": "XYZ-1",
            "c_data": [
                {
                    "u_label": "XYZ-1",
                    "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
                    "u_value": "32192"
                }
            ]
        }
        
    ]
} 

I am not sure how to use loop here to run 3 or 4 time depend upon the data. using below jinja template.

   {% for n in range(count) %}
            "u_label": "{{ datastore_details[item | int]['name'] }}",
            "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
            "u_value": "{{ datastore_details[item | int]['size'] }}",
            "c_data": [
                {
                    "u_label": "{{ datastore_details[item | int]['name'] }}",
                    "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
                    "u_value": "{{ datastore_details[item | int]['size'] }}"
                }
            ]
    {% endfor %}

Answer 1

The only clean way I found to do this was Create the json file and insert your variables where you want them as you would with any template file

"mariaDB": {
    "type": "object",
    "description": "Add this section to connect MeshCentral to a MariaDB database instance.",
    "properties": {
            "host": "{{ sm_internal_ip }}",
            "user": "{{ mesh_central_db_admin_user }}",
            "port": 3306,
            "password": "{{ mesh_central_db_admin_password }}",
            "database": "{{ mesh_central_db_name }}"
    }

},

Copy the file over using the Ansible copy command

    - name: copy the json file over
      copy:
        src: "config.json"
        dest: "/SM_DATA/mesh_central/meshcentral-data/config.json"
        mode: 0644 

Do a string replace of your {{ variables }} using the following command

- name: Ansible multiple replace example
  replace:
     path: "/SM_DATA/mesh_central/meshcentral-data/config.json"
     regexp: "{{ item.regexp1 }}"
     replace: "{{ item.replace }}"
  with_items:
  - { regexp1: "{% raw %}{{ public_domain_name }}{% endraw %}", replace: "{{ public_domain_name }}"}
  - { regexp1: "{% raw %}{{ sm_internal_ip }}{% endraw %}", replace: "{{ sm_internal_ip }}"}    
  - { regexp1: "{% raw %}{{ mesh_central_db_name }}{% endraw %}", replace: "{{ sm_mesh_central_db_nameinternal_ip }}"}    
  - { regexp1: "{% raw %}{{ mesh_central_db_admin_user }}{% endraw %}", replace: "{{ mesh_central_db_admin_user }}"}    
  - { regexp1: "{% raw %}{{ mesh_central_db_admin_password }}{% endraw %}", replace: "{{ mesh_central_db_admin_password }}"}    

This gave me the end result I was looking for.

Answer 2

First of all you need to get those variables into ansible. The easiest way is to define them in the inventory. If you can not do that (e.g. because this json file is generated on the host), you can use the include_vars module to load the variables.

Assuming you have your variables accessible to ansible, you can loop over the list in a jinja2 template like this:

Example Inventory:

---
all:
  hosts:
    localhost:
      ansible_connection: local
      datastore_details: 
        - name: "XYZ"
          size: 6258
        - name: "XYZ-1"
          size: 32192
        - name: "as-many-as-you-want"
          size: 1337

Example Playbook:

---
- hosts: all
  tasks:    

  # if you have your variables somewhere else, use the `include_vars` module here

  - name: template
    template:
      src: tmpl.j2
      dest: /tmp/out.file

Example Template:

... some data ...

{% for d in datastore_details %}
         "u_label": "{{ d['name'] }}",
         "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
         "u_value": "{{ d['size'] }}",
         "c_data": [
             {
                 "u_label": "{{ d['name'] }}",
                 "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
                 "u_value": "{{ d['size'] }}"
             }
         ]

... some data in between ...

{% endfor %}

... some more data ...

Output:

... some data ...

         "u_label": "XYZ",
         "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
         "u_value": "6258",
         "c_data": [
             {
                 "u_label": "XYZ",
                 "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
                 "u_value": "6258"
             }
         ]

... some data in between ...

         "u_label": "XYZ-1",
         "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
         "u_value": "32192",
         "c_data": [
             {
                 "u_label": "XYZ-1",
                 "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
                 "u_value": "32192"
             }
         ]

... some data in between ...

         "u_label": "as-many-as-you-want",
         "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
         "u_value": "1337",
         "c_data": [
             {
                 "u_label": "as-many-as-you-want",
                 "u_catalog_item": "c08c7936db71d4503fa396f8f49619db",
                 "u_value": "1337"
             }
         ]

... some data in between ...


... some more data ...

The important thing here is to get your data in as variables, I do it using the inventory, but (as said before) you can use include_vars to load variables on the host you are running on.