Why Configuration Management

byMy Scribble Pads -


📌Why Configuration Management?

🔍 Scenario Overview: E-commerce Application Deployment

To deploy an e-commerce application, you need two Ubuntu Linux servers:

1. Database Server

Tasks to configure:

  • Update Linux OS (sudo apt update && sudo apt upgrade)
  • Add necessary Linux users (adduser, usermod)
  • Install PostgreSQL (sudo apt install postgresql)

  • Configure PostgreSQL:

    • Create a database
    • Create and assign a database user
    • Set proper authentication in pg_hba.conf

2. Application Server

Tasks to configure:

  • Update Linux OS
  • Add necessary users
  • Install Java (sudo apt install default-jdk)
  • Install Tomcat (download, extract, configure)
  • Deploy application (typically WAR file to Tomcat webapps directory)

⚙️ Deployment Strategy

🌐 Deploying to Different Environments (e.g., ST, UAT, PROD)

When the application is updated, it must be re-deployed across all environments.

🧍 Manual Approach:

  • Involves running all setup commands yourself

  • Drawbacks:

    • Time-consuming
    • Error-prone
    • Not repeatable

🤖 Automated Approach:

  • Faster, repeatable, and consistent
  • Essential for scaling and maintaining multiple environments

🧰 Automation Methods

1. Procedural Automation (Scripted Approach)

  • Describes how to do something, step-by-step

  • Example: Bash script to install Apache

    sudo apt update
sudo apt install apache2 -y
sudo systemctl enable apache2
sudo systemctl start apache2

  • Pros:

    • Simple and direct

  • Cons:

    • Harder to maintain
    • No built-in idempotence (re-running may cause issues)

2. Declarative Automation (Configuration Management)

  • Describes the desired state, not the steps
  • Tools interpret the desired state and bring the system to it

  • Example: Ansible/YAML to ensure Apache is:

    • Installed
    • Enabled
    • Running

  • Benefits:

    • Easy to read and manage
    • Idempotent – same result on every execution
    • Scalable across multiple machines

✅ What Is Configuration Management?

  • Configuration Management is software-based automation that:

    • Configures systems declaratively
    • Ensures idempotence
    • Keeps system states consistent across environments

🛠 Popular Configuration Management Tools:

  • Ansible
  • Chef
  • Puppet
  • SaltStack

🧗 Steps to Learn Configuration Management with Ansible

  1. Be Comfortable with Command Line

    • Understand how to execute and troubleshoot shell commands

  2. Manual Process First

    • Know how to perform each step manually before automating

  3. Learn YAML (Yet Another Markup Language)

    • Ansible playbooks are written in YAML

  4. Understand Ansible Concepts:

    • Inventory
    • Playbooks
    • Tasks
    • Modules
    • Roles

  5. Basic Linux Knowledge:

    • Working with users, services, file permissions, package managers

🐧 Linux Basics

1. Kernel

  • Core part of the OS
  • Manages communication between hardware and software

2. Distributions

  • OS variants built around the Linux kernel
  • Add software and provide package managers

Popular Families:

  • Debian-based:

    • Ubuntu
    • Kali Linux
    • Linux Mint
    • Package Manager: apt

  • Red Hat-based:

    • Fedora
    • RHEL (Red Hat Enterprise Linux)
    • Amazon Linux
    • Rocky Linux
    • Package Manager: yum or dnf

3. Shell

  • Interface between user and OS kernel
  • Accepts and executes commands (e.g., Bash)

📝 Exercise: What is a Daemon in Linux?

  • A daemon is a background process that:

    • Runs continuously
    • Starts at boot or manually
    • Provides services (e.g., web server, database)

  • Examples:

    • sshd – SSH daemon
    • httpd – Apache HTTP daemon
    • postgres – PostgreSQL daemon
  • Typically end with d

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