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Ansible Level 02 Day 05: Ansible Blockinfile Module

This document outlines the solution for Ansible Level 02 Day 05. The objective was to use Ansible to install the httpd web server on all application servers, ensure its service is running, and deploy a sample web page using the blockinfile module.

Table of Contents

  1. Task Overview
  2. Step-by-Step Solution
  3. Deep Dive: Ansible Concepts Used

Task Overview

Objective: Install a web server and configure an index.html file using blockinfile.

  • Playbook Location: /home/thor/ansible/playbook.yml
  • Inventory Location: /home/thor/ansible/inventory (Already exists)
  • Target Hosts: All app servers (hosts: all)
  • Tasks Required:
    1. Install httpd package.
    2. Start and enable httpd service.
    3. Create /var/www/html/index.html and add specific multi-line content.
  • File Requirements:
    • Owner/Group: apache
    • Permissions: 0777
  • Constraint: Must run cleanly using ansible-playbook -i inventory playbook.yml and must not use custom markers for the blockinfile module.

Step-by-Step Solution

1. Verify the Environment

Since the inventory file is already provided, quickly review it to ensure it contains the connection variables for the target servers.

Command: 

cat /home/thor/ansible/inventory
Ensure it is properly formatted so we don't need to pass extra connection arguments during playbook execution.

2. Create the Playbook

Create the YAML playbook to execute the required tasks. Because we are installing packages, managing services, and modifying files in /var/www/html/, we must use become: yes to execute with root privileges.

Command: 

vi /home/thor/ansible/playbook.yml

Content: 

---
- name: Set up httpd web server and sample page
  hosts: all
  become: yes
  tasks:
    - name: Install httpd package
      yum:
        name: httpd
        state: present

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

    - name: Add sample content to index.html
      blockinfile:
        path: /var/www/html/index.html
        create: yes
        block: |
          Welcome to XfusionCorp!
          This is  Nautilus sample file, created using Ansible!
          Please do not modify this file manually!
        owner: apache
        group: apache
        mode: '0777'

3. Execute and Validate

Run the playbook using the specific command required for validation.

Command: 

cd /home/thor/ansible/
ansible-playbook -i inventory playbook.yml

Expected Output: 

PLAY [Set up httpd web server and sample page] *****************************************

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

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

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

TASK [Add sample content to index.html] ***********************************************
changed: [stapp01]
changed: [stapp02]
changed: [stapp03]

PLAY RECAP ****************************************************************************
stapp01                    : ok=4    changed=3    unreachable=0    failed=0    ...
stapp02                    : ok=4    changed=3    unreachable=0    failed=0    ...
stapp03                    : ok=4    changed=3    unreachable=0    failed=0    ...

Manual Verification (Optional): You can verify the file was created correctly using an ad-hoc command: 

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

Deep Dive: Ansible Concepts Used

The blockinfile Module

The blockinfile module is designed to insert, update, or remove a multi-line block of text within a file. It is extremely useful for configuring configuration blocks (like virtual hosts or multi-line settings). * create: yes: This tells Ansible to create the file if it does not already exist. Without this, the task would fail if index.html wasn't already present. * block: |: The pipe (|) character in YAML denotes a literal block scalar. It preserves the newlines and exact formatting of the text that follows it. * Default Markers: By default, Ansible wraps the inserted block in comment markers (e.g., # BEGIN ANSIBLE MANAGED BLOCK and # END ANSIBLE MANAGED BLOCK). The task constraints specifically required us not to use custom markers (which are normally defined using the marker parameter), so we simply left the parameter out, allowing Ansible to use its default behavior.

Execution Order

The order of tasks in the playbook is critical: 1. Install httpd: This step ensures that the apache user and group are created on the system, and that the /var/www/html directory structure is provisioned. 2. Manage Service: Starts the web server. 3. Create File: If we tried to create the file before installing httpd, the task would fail because the /var/www/html path might not exist, and the apache user/group definitely wouldn't exist to assign ownership.