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DevOps Day 83: Ansible Playbooks & File Management

This document provides a comprehensive guide to completing the Ansible task for DevOps Day 83. It covers troubleshooting an existing inventory configuration and creating a new playbook to manage files on a remote application server.

Table of Contents

Task Overview

Objective: The Nautilus DevOps team needs to complete an unfinished Ansible setup on the jump host. You must fix the inventory file and create a playbook to generate a file on App Server 1.

Requirements: 1. Inventory Adjustment: Update /home/thor/ansible/inventory to include App Server 1 (stapp01) with the correct connection credentials. 2. Playbook Creation: Create /home/thor/ansible/playbook.yml. 3. Task: The playbook must create an empty file named /tmp/file.txt on App Server 1. 4. Validation: Run ansible-playbook -i inventory playbook.yml.

Step-by-Step Solution

1. Update the Inventory File

The existing inventory file is incomplete. We need to define the host stapp01 and provide the SSH user and password.

  • Host: stapp01
  • User: tony
  • Password: Ir0nM@n

Command: 

cd /home/thor/ansible/
vi inventory

Content: 

stapp01 ansible_host=stapp01 ansible_user=tony ansible_ssh_pass=Ir0nM@n ansible_ssh_common_args='-o StrictHostKeyChecking=no'
Note: Adding ansible_ssh_common_args='-o StrictHostKeyChecking=no' is a pro-tip. It prevents the playbook from hanging on the "Are you sure you want to connect?" prompt.

2. Create the Playbook

We need a YAML file that defines the play.

Command: 

vi playbook.yml

Content: 

---
- name: Configure App Server 1
  hosts: stapp01
  become: yes  # Optional: Use if /tmp requires elevated privileges (usually not needed for /tmp)
  tasks:
    - name: Create an empty file at /tmp/file.txt
      file:
        path: /tmp/file.txt
        state: touch

Breakdown: * hosts: stapp01: Tells Ansible to run these tasks only on the server labelled stapp01 in our inventory. * file module: The dedicated module for managing file properties. * state: touch: Similar to the Linux touch command—it creates the file if it doesn't exist, or updates the timestamp if it does.

3. Validate and Execute

Run the playbook using the inventory you created.

Command: 

ansible-playbook -i inventory playbook.yml

Expected Output: 

PLAY [Configure App Server 1] *******************************************************

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

TASK [Create an empty file at /tmp/file.txt] ****************************************
changed: [stapp01]

PLAY RECAP **************************************************************************
stapp01                    : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Deep Dive: Ansible Concepts Used

The file Module

The file module is your Swiss Army knife for filesystem operations. It can create files, directories, symlinks, and modify permissions.

  • Create a directory: state: directory
  • Create a file: state: touch
  • Remove a file: state: absent
  • Change permissions: mode: '0755'

Inventory Variables

In the inventory file, we used inline variables to define how Ansible connects:

Variable Description
ansible_host The actual IP or FQDN of the server.
ansible_user The username SSH uses to login.
ansible_ssh_pass The password for the user.
ansible_ssh_common_args Additional arguments passed to the SSH command line (useful for bypassing host key checking).

Troubleshooting

Issue: "Host Key Verification Failed" * Cause: This is the first time connecting to stapp01, and SSH is waiting for you to type "yes" to accept the fingerprint. * Fix: Ensure you included ansible_ssh_common_args='-o StrictHostKeyChecking=no' in your inventory file. Alternatively, run ssh tony@stapp01 manually once and accept the key.

Issue: "Permission Denied" * Cause: Incorrect password or username. * Fix: Double check that ansible_user=tony and ansible_ssh_pass=Ir0nM@n. Note that Ir0nM@n has special characters; ensure no extra spaces were pasted.

Issue: "Authentication failed" using ansible_ssh_password * Note: The standard variable is ansible_ssh_pass. While ansible_ssh_password works in many contexts/plugins, ansible_ssh_pass is the traditional default for the connection variable. If one fails, try the other.