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Ansible Level 04 Day 01: Ansible Facts Gathering

This document outlines the solution for Ansible Level 04 Day 01. The objective was to configure a simple Apache web server across all application servers and populate the default index.html file with dynamically generated content using Ansible Facts.

Table of Contents

Task Overview

Objective: Install an httpd web server and create a dynamically generated index.html file that displays the managed node's architecture.

Requirements: 1. Playbook Location: /home/thor/playbooks/index.yml 2. Inventory Location: /home/thor/playbooks/inventory (Already exists) 3. Target Hosts: All app servers 4. Tasks Required: * Create a file /root/facts.txt using the blockinfile module. * The block must contain: Ansible managed node architecture is <architecture> (using the gathered fact variable). * Install the httpd server. * Copy /root/facts.txt to /var/www/html/index.html. * Start the httpd service. 5. Constraint: Do not use separate roles. Include all tasks sequentially within index.yml.

Step-by-Step Solution

1. Verify the Environment

First, confirm that the inventory file exists and is correctly located in the playbooks directory.

Command: 

cd /home/thor/playbooks
cat inventory

2. Create the Playbook

Create the single index.yml playbook. Since we are creating files in /root, installing packages, and managing system services, we must use become: yes to execute with root privileges. We must also ensure gather_facts: yes is set so the ansible_architecture variable is populated.

Command: 

vi index.yml

Content: 

---
- name: Setup httpd and gather system facts
  hosts: all
  become: yes
  gather_facts: yes
  tasks:
    - name: Create facts.txt with architecture information
      blockinfile:
        path: /root/facts.txt
        create: yes
        block: |
          Ansible managed node architecture is {{ ansible_architecture }}

    - name: Install httpd server
      yum:
        name: httpd
        state: present

    - name: Copy facts.txt to index.html
      copy:
        src: /root/facts.txt
        dest: /var/www/html/index.html
        remote_src: yes

    - name: Start and enable httpd service
      service:
        name: httpd
        state: started
        enabled: yes

3. Execute and Validate

Run the playbook from the directory containing the inventory file.

Execution Command: 

ansible-playbook -i inventory index.yml

Expected Output: 

PLAY [Setup httpd and gather system facts] *******************************************

TASK [Gathering Facts] ***************************************************************
ok: [stapp01]
ok: [stapp02]
ok: [stapp03]

TASK [Create facts.txt with architecture information] ********************************
changed: [stapp01]
changed: [stapp02]
changed: [stapp03]

TASK [Install httpd server] **********************************************************
changed: [stapp01]
changed: [stapp02]
changed: [stapp03]

TASK [Copy facts.txt to index.html] **************************************************
changed: [stapp01]
changed: [stapp02]
changed: [stapp03]

TASK [Start and enable httpd service] ************************************************
changed: [stapp01]
changed: [stapp02]
changed: [stapp03]

PLAY RECAP ***************************************************************************
stapp01                    : ok=5    changed=4    unreachable=0    failed=0    ...
stapp02                    : ok=5    changed=4    unreachable=0    failed=0    ...
stapp03                    : ok=5    changed=4    unreachable=0    failed=0    ...

Manual Verification (Optional): To independently verify the content has correctly rendered the x86_64 (or similar) architecture string, use an ad-hoc command: 

ansible all -i inventory -m command -a "cat /var/www/html/index.html" --become

Deep Dive: Ansible Concepts Used

Ansible Facts Gathering

Ansible Facts are data gathered about the target nodes before executing the main tasks. This is represented by the implicit TASK [Gathering Facts] step. * gather_facts: yes: While this is the default behavior in Ansible, explicitly stating it ensures the playbook is readable and self-documenting. * {{ ansible_architecture }}: This is a specific fact collected by the setup module. When Ansible runs on the target node, it evaluates its architecture (e.g., x86_64, aarch64) and replaces the Jinja2 variable with the real value.

(Pro tip: To see all available facts for a host, you can run ansible stapp01 -i inventory -m setup)

Remote File Copying

In the copy task, we used remote_src: yes. * Without remote_src (Default): Ansible expects the src file to exist on the Control Node (the Jump Host) and copies it across the network to the Managed Node. * With remote_src: yes: Ansible knows the src file already exists on the Managed Node (because we just created it in /root during the previous step). It executes a local copy command directly on the target server, moving the file from /root/facts.txt to /var/www/html/index.html.