Extracting JSON Data with Ansible

Learn how to use Ansible to extract specific JSON data efficiently with the json_query filter, showcasing an example of retrieving folder values based on names.

Introduction

JSON (JavaScript Object Notation) is a common data format for APIs and configuration management. In modern IT operations, querying JSON data is essential for automation. Ansible, a powerful tool for automating IT tasks, offers a robust json_query filter that simplifies querying and extracting data. In this article, we will demonstrate how to use Ansible to extract a folder value from a JSON structure based on a specific name.

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1. Why Automate JSON Queries?

JSON queries can become repetitive and error-prone when done manually. Automating this process with Ansible provides several advantages:

Consistency: Avoid manual errors by standardizing queries.

Efficiency: Save time with automated data extraction.

Flexibility: Adapt quickly to changes in JSON structures.

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2. Example Use Case: Extracting Folder Value by Name

Let’s consider a scenario where you need to extract the folder value for a specific name from JSON data.

The JSON Data

Here’s an example JSON structure:

``yaml


[
  { "name": "foo", "folder": "foo_folder" },
  { "name": "bar", "folder": "bar_folder" }
]



The Goal

Retrieve the folder value for name: foo using Ansible.



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3. The Playbook

Below is the Ansible playbook for this task:

`yaml


---
name: Extract folder value based on name
  hosts: localhost
  gather_facts: no
  vars:
    # Sample JSON data
    json_data:
      - { "name": "foo", "folder": "foo_folder" }
      - { "name": "bar", "folder": "bar_folder" }
    # Query to extract the folder value for the given name
    query: "[?name=='{{ lookup_name }}'].folder | [0]"
    # Variable to hold the name for which the folder value is queried
    lookup_name: foo

  tasks:
    - name: Extract folder value for name={{ lookup_name }}
      set_fact:
        folder_value: "{{ json_data | json_query(query) }}"

    - name: Display extracted folder value
      debug:
        msg: "The folder value for '{{ lookup_name }}' is '{{ folder_value }}'"



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4. Understanding the Playbook

JSON Data

The json_data variable represents the data to be queried. It’s a list of dictionaries with name and folder fields.



Query Syntax

The json_query filter uses JMESPath syntax for querying:

?name=='{{ lookup_name }}': Filters objects with name matching lookup_name.

.folder: Retrieves the folder field from the matched objects.

[0]: Selects the first match.

set_fact

The set_fact module dynamically sets the folder_value variable with the query result.



Debugging

The debug module displays the extracted folder value, verifying the playbook's success.



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5. Running the Playbook

Save the playbook as extract_folder.yml and execute it with:

`bash


ansible-playbook extract_folder.yml



Example Output


TASK [Display extracted folder value] **
ok: [localhost] => {
    "msg": "The folder value for 'foo' is 'foo_folder'"
}