DevOps-Containerization

Experiment 9 – Ansible Automation with Docker (WSL-Based Windows Environment)

Table of Contents

1. Introduction
2. Objectives
3. System Architecture
4. Prerequisites
5. Detailed Theory
6. Installation and Configuration
7. SSH Key-Based Authentication
8. Docker Environment Setup
9. Container Deployment Strategy
10. Ansible Inventory Configuration
11. Playbook Design and Execution
12. Verification and Validation
13. Results and Observations
14. Troubleshooting and Error Handling
15. Key Concepts
16. Learning Outcomes
17. Conclusion
18. Repository Structure

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1. Introduction

This experiment demonstrates the implementation of configuration management and automation using Ansible over multiple Docker containers acting as remote servers. The entire setup is executed within a Windows environment using Windows Subsystem for Linux (WSL), ensuring compatibility with native Linux-based tools.

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2. Objectives

• To understand the working of Ansible as a configuration management tool
• To simulate multiple servers using Docker containers
• To establish SSH key-based authentication between control node and managed nodes
• To automate tasks across multiple nodes using YAML-based playbooks
• To demonstrate Infrastructure as Code (IaC) principles

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3. System Architecture

The architecture consists of a control node and multiple managed nodes.

Control Node:

• WSL Ubuntu environment
• Ansible installed

Managed Nodes:

• Docker containers running Ubuntu
• SSH server enabled

Communication:

• SSH protocol using key-based authentication

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4. Prerequisites

• Windows 10/11
• WSL installed with Ubuntu
• Docker Desktop with WSL integration enabled
• Basic knowledge of Linux commands

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5. Detailed Theory

What is Ansible

Ansible is an open-source automation tool used for configuration management, application deployment, and orchestration. It operates without agents and uses SSH for communication.

Key Features

• Agentless architecture
• Idempotency
• Declarative configuration
• YAML-based playbooks

Docker Role

Docker is used to create lightweight containers that simulate multiple servers locally.

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6. Installation and Configuration

Fixing Dependencies

sudo dpkg –configure -a sudo apt –fix-broken install -y

Installing Ansible

sudo apt update sudo apt install ansible -y

Verification

ansible –version

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7. SSH Key-Based Authentication

Generate Key

ssh-keygen -t rsa -b 4096

Copy Keys

cp ~/.ssh/id_rsa . cp ~/.ssh/id_rsa.pub .

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8. Docker Environment Setup

Dockerfile Configuration

FROM ubuntu

RUN apt update -y RUN apt install -y python3 openssh-server RUN mkdir -p /var/run/sshd

RUN mkdir -p /run/sshd &&
echo ‘root:password’ | chpasswd &&
sed -i ‘s/#PermitRootLogin prohibit-password/PermitRootLogin yes/’ /etc/ssh/sshd_config &&
sed -i ‘s/#PasswordAuthentication yes/PasswordAuthentication no/’ /etc/ssh/sshd_config &&
sed -i ‘s/#PubkeyAuthentication yes/PubkeyAuthentication yes/’ /etc/ssh/sshd_config

RUN mkdir -p /root/.ssh COPY id_rsa /root/.ssh/id_rsa COPY id_rsa.pub /root/.ssh/authorized_keys

RUN chmod 600 /root/.ssh/id_rsa RUN chmod 644 /root/.ssh/authorized_keys

EXPOSE 22 CMD [“/usr/sbin/sshd”, “-D”]

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9. Container Deployment Strategy

Build Image

docker build -t ubuntu-server .

Run Containers

for i in {1..4}; do docker run -d -p 220$i:22 –name server$i ubuntu-server done

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10. Ansible Inventory Configuration

[servers] localhost:2201 localhost:2202 localhost:2203 localhost:2204

[servers:vars] ansible_user=root ansible_ssh_private_key_file=~/.ssh/id_rsa ansible_connection=ssh

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11. Playbook Design and Execution

playbook.yml

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• name: Configure servers hosts: servers become: yes

  tasks:

  • name: Update packages apt: update_cache: yes

  • name: Install packages apt: name: [“vim”, “htop”, “wget”] state: present

  • name: Create file copy: dest: /root/test_file.txt content: “Configured using Ansible automation”

Execution

ansible-playbook -i inventory.ini playbook.yml

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12. Verification and Validation

ansible all -i inventory.ini -m command -a “cat /root/test_file.txt”

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13. Results and Observations

• Successful SSH communication established
• All containers responded to Ansible ping
• Playbook executed across all nodes
• Configuration applied consistently

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14. Troubleshooting and Error Handling

• Fixed dpkg dependency issues
• Enabled Docker WSL integration
• Verified SSH connectivity before automation
• Used logs for debugging containers

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15. Key Concepts

• Control Node
• Managed Nodes
• Inventory
• Playbooks
• Modules
• Idempotency

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16. Learning Outcomes

• Practical understanding of Ansible
• Automation of multi-node systems
• Use of Docker for simulation
• Implementation of IaC principles

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17. Conclusion

The experiment successfully demonstrates the power of Ansible in automating infrastructure tasks across multiple nodes using a Windows-based setup with WSL.

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18. Repository Structure

. ├── Dockerfile ├── inventory.ini ├── playbook.yml ├── README.md └── screenshots

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