Complete DevOps Foundation Tutorials for Linux Admins - Textnotes

Complete DevOps Foundation Tutorials for Linux Admins

A step-by-step DevOps foundation guide covering Git, GitHub, Ansible, Jenkins, Docker, Kubernetes, and AWS basics tailored for Linux administrators.

1. Git and GitHub

Git is the most widely used version-control system. As a Linux Admin/DevOps engineer, you must know Git to manage scripts, automation code, infra-as-code, CI/CD pipelines, etc.

Install Git

RHEL/CentOS

sudo yum install git -y

Ubuntu

sudo apt install git -y

Configure Git

git config --global user.name "Muni"

git config --global user.email "muni@example.com"

Basic Git Commands

Initialize a repo

git init

Clone a repo

git clone https://github.com/user/repo.git

Check file status

git status

Add files

git add .

Commit changes

git commit -m "Updated script"

Push to GitHub

git push origin main

Pull changes

git pull

Git Branching

git branch dev

git checkout dev

Merge Branch

git checkout main

git merge dev

2. Ansible

Ansible is an automation tool used for configuration management, patching, deployments, and orchestration.

Install Ansible (RHEL)

sudo yum install ansible -y

Inventory File Example (/etc/ansible/hosts)

[web]

192.168.1.10

192.168.1.11

[db]

192.168.1.20

Test Connection

ansible all -m ping

Run a Command on All Servers

ansible all -a "uptime"

Simple Playbook Example

playbook.yml

- hosts: web

tasks:

- name: Install httpd

yum:

name: httpd

state: present

Run:

ansible-playbook playbook.yml

3. Jenkins Basics

Jenkins is a CI/CD automation tool widely used to automate deployments and build pipelines.

Install Jenkins (RHEL/CentOS)

sudo yum install java-11-openjdk -y

sudo yum install jenkins -y

sudo systemctl start jenkins

sudo systemctl enable jenkins

Access UI

http://<server-ip>:8080

Basic Jenkins Concepts

TermMeaning
Job/Project	The task Jenkins executes
Pipeline	Scripted/Declarative automated flow
Build	Running the job
Workspace	Directory where Jenkins runs builds

Create First Freestyle Job

Steps:

New Item
Freestyle Project
Add Build Step → Execute shell
Example:

echo "Deploying to dev environment"

Save → Build Now

Simple Jenkins Pipeline Example

pipeline {

agent any

stages {

stage('Build') {

steps {

echo "Building Application..."

}

stage('Deploy') {

steps {

echo "Deploying App..."

}

4. Docker

Docker allows you to run applications in lightweight containers.

Install Docker

sudo yum install docker -y

sudo systemctl start docker

sudo systemctl enable docker

Basic Commands

Pull Image

docker pull nginx

Run Container

docker run -d -p 8080:80 nginx

List Containers

docker ps

Stop Container

docker stop <container_id>

Remove Container

docker rm <container_id>

Build Docker Image

Create Dockerfile:

FROM ubuntu

RUN apt-get update

CMD ["echo", "Hello from Docker"]

Build:

docker build -t myimage .

Run:

docker run myimage

5. Kubernetes Fundamentals

Kubernetes (K8s) manages containerized applications.

Key Components

ComponentDescription
Pod	Smallest unit in Kubernetes
Node	Worker machine
Deployment	Controller for pods
Service	Access pods internally/externally
Namespace	Logical separation

Install Kubernetes (Minikube)

minikube start

Check Cluster Status

kubectl get nodes

Create Deployment

kubectl create deployment web --image=nginx

Expose Deployment

kubectl expose deployment web --port=80 --type=NodePort

Check Services

kubectl get svc

Scale Application

kubectl scale deployment web --replicas=3

6. AWS Basics (EC2, VPC, IAM, S3)

AWS is the #1 cloud platform used by DevOps engineers.

EC2 (Linux server creation)

Launch EC2