Extracting JSON Data with Ansible

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.

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.

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:

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

The Goal

Retrieve the folder value for name: foo using Ansible.

3. The Playbook

Below is the Ansible playbook for this task:

---
- 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 }}'"

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.

5. Running the Playbook

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

ansible-playbook extract_folder.yml

Example Output

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

6. Extending the Playbook

• Dynamic Input: Replace lookup_name with an external variable for flexibility:

  ansible-playbook extract_folder.yml -e "lookup_name=bar"
  

• Handling Multiple Results: To retrieve all matching values, remove [0] from the query:

  query: "[?name=='{{ lookup_name }}'].folder"
  

Conclusion

Ansible’s json_query filter simplifies working with JSON data, enabling administrators to extract critical values with precision. By automating this process, you can streamline workflows, minimize errors, and handle complex JSON structures effortlessly.

Integrate this playbook into your automation toolkit to unlock new efficiencies in JSON data management!

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