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Containers & Virtualization

Docker Basics​

Docker Installation and Setup​

# Install Docker (Ubuntu/Debian)
sudo apt update
sudo apt install docker.io
sudo systemctl start docker
sudo systemctl enable docker

# Add user to docker group (avoid sudo)
sudo usermod -aG docker $USER
newgrp docker

# Verify installation
docker --version
docker info
docker run hello-world

Image Management​

# Search for images
docker search nginx
docker search --limit=5 ubuntu

# Pull images
docker pull nginx
docker pull nginx:1.20
docker pull ubuntu:20.04

# List images
docker images
docker image ls
docker images -a                    # Show all images including intermediate

# Remove images
docker rmi image_name
docker rmi image_id
docker image prune                  # Remove unused images
docker image prune -a               # Remove all unused images

Container Lifecycle​

# Run containers
docker run nginx                    # Run and attach to container
docker run -d nginx                 # Run in background (detached)
docker run -it ubuntu bash          # Interactive with terminal
docker run --name myapp nginx       # Assign custom name
docker run -p 8080:80 nginx         # Port mapping (host:container)
docker run -v /host/path:/container/path nginx  # Volume mount

# List containers
docker ps                           # Running containers
docker ps -a                        # All containers
docker ps -q                        # Only container IDs

# Container control
docker start container_name
docker stop container_name
docker restart container_name
docker pause container_name
docker unpause container_name

# Remove containers
docker rm container_name
docker rm -f container_name         # Force remove running container
docker container prune              # Remove stopped containers

Container Interaction​

# Execute commands in running container
docker exec -it container_name bash
docker exec container_name ls /app
docker exec -u root container_name apt update

# Copy files between host and container
docker cp file.txt container_name:/path/to/
docker cp container_name:/path/to/file.txt ./

# View container logs
docker logs container_name
docker logs -f container_name       # Follow logs
docker logs --tail 100 container_name
docker logs --since "2023-01-01" container_name

# Inspect container details
docker inspect container_name
docker stats container_name         # Real-time resource usage
docker top container_name           # Processes in container

Docker Networking​

Network Management​

# List networks
docker network ls

# Create networks
docker network create mynetwork
docker network create --driver bridge mybridge
docker network create --driver overlay myoverlay

# Inspect network
docker network inspect bridge
docker network inspect mynetwork

# Connect/disconnect containers
docker network connect mynetwork container_name
docker network disconnect mynetwork container_name

# Remove networks
docker network rm mynetwork
docker network prune               # Remove unused networks

Network Types and Usage​

# Bridge network (default)
docker run --network bridge nginx

# Host network (use host's network)
docker run --network host nginx

# Custom network
docker run --network mynetwork nginx

# Container communication
docker run --name app1 --network mynetwork nginx
docker run --name app2 --network mynetwork --link app1 ubuntu

Docker Volumes​

Volume Management​

# Create volumes
docker volume create myvolume
docker volume create --driver local myvolume

# List volumes
docker volume ls

# Inspect volume
docker volume inspect myvolume

# Remove volumes
docker volume rm myvolume
docker volume prune                # Remove unused volumes

Volume Types​

# Named volumes
docker run -v myvolume:/data nginx

# Host bind mounts
docker run -v /host/path:/container/path nginx
docker run -v $(pwd):/app nginx    # Current directory

# Anonymous volumes
docker run -v /container/path nginx

# Read-only volumes
docker run -v /host/path:/container/path:ro nginx

# Tmpfs mounts (memory)
docker run --tmpfs /tmp nginx

Docker Build​

Dockerfile Basics​

# Example Dockerfile
FROM ubuntu:20.04
LABEL maintainer="user@example.com"

# Install packages
RUN apt-get update && apt-get install -y \
    nginx \
    curl \
    && rm -rf /var/lib/apt/lists/*

# Set working directory
WORKDIR /app

# Copy files
COPY . .
ADD https://example.com/file.tar.gz /tmp/

# Set environment variables
ENV NODE_ENV=production
ENV PATH=/app/bin:$PATH

# Expose ports
EXPOSE 80 443

# Create user
RUN useradd -m appuser
USER appuser

# Set entrypoint and command
ENTRYPOINT ["./entrypoint.sh"]
CMD ["nginx", "-g", "daemon off;"]

Build Commands​

# Build image
docker build -t myapp .
docker build -t myapp:v1.0 .
docker build -f Dockerfile.prod -t myapp:prod .

# Build with arguments
docker build --build-arg VERSION=1.0 -t myapp .

# Multi-stage build
docker build --target production -t myapp:prod .

# Build cache management
docker build --no-cache -t myapp .
docker system prune -a             # Clean build cache

Docker Compose​

Docker Compose Basics​

# docker-compose.yml
version: '3.8'

services:
  web:
    build: .
    ports:
      - '8080:80'
    volumes:
      - ./app:/var/www/html
    environment:
      - NODE_ENV=production
    depends_on:
      - db
    networks:
      - app-network

  db:
    image: postgres:13
    environment:
      POSTGRES_DB: myapp
      POSTGRES_USER: user
      POSTGRES_PASSWORD: password
    volumes:
      - db_data:/var/lib/postgresql/data
    networks:
      - app-network

volumes:
  db_data:

networks:
  app-network:
    driver: bridge

Compose Commands​

# Start services
docker-compose up
docker-compose up -d               # Detached mode
docker-compose up --build          # Rebuild images
docker-compose up --scale web=3    # Scale service

# Stop services
docker-compose down
docker-compose down -v             # Remove volumes
docker-compose down --rmi all      # Remove images

# Service management
docker-compose start
docker-compose stop
docker-compose restart
docker-compose pause
docker-compose unpause

# View services
docker-compose ps
docker-compose logs
docker-compose logs -f web         # Follow logs for specific service
docker-compose top                 # Show running processes

# Execute commands
docker-compose exec web bash
docker-compose run web npm install

Container Registry​

Docker Hub​

# Login to Docker Hub
docker login
docker login -u username

# Tag images for registry
docker tag myapp:latest username/myapp:latest
docker tag myapp:latest username/myapp:v1.0

# Push to registry
docker push username/myapp:latest
docker push username/myapp:v1.0

# Pull from registry
docker pull username/myapp:latest

# Logout
docker logout

Private Registry​

# Run local registry
docker run -d -p 5000:5000 --name registry registry:2

# Tag for private registry
docker tag myapp localhost:5000/myapp

# Push to private registry
docker push localhost:5000/myapp

# Pull from private registry
docker pull localhost:5000/myapp

Kubernetes Basics​

Cluster Management​

# Cluster information
kubectl cluster-info
kubectl get nodes
kubectl get nodes -o wide
kubectl describe node node-name

# Namespaces
kubectl get namespaces
kubectl create namespace myapp
kubectl delete namespace myapp
kubectl config set-context --current --namespace=myapp

Pod Management​

# Create and manage pods
kubectl run nginx --image=nginx
kubectl run nginx --image=nginx --port=80
kubectl run nginx --image=nginx --dry-run=client -o yaml > pod.yaml

# List pods
kubectl get pods
kubectl get pods -o wide
kubectl get pods --all-namespaces
kubectl get pods -l app=nginx      # Filter by label

# Pod details
kubectl describe pod pod-name
kubectl logs pod-name
kubectl logs -f pod-name           # Follow logs
kubectl logs pod-name -c container-name  # Multi-container pod

# Execute commands in pod
kubectl exec -it pod-name -- bash
kubectl exec pod-name -- ls /app

# Port forwarding
kubectl port-forward pod-name 8080:80

# Delete pods
kubectl delete pod pod-name
kubectl delete pods --all

Deployments​

# Create deployment
kubectl create deployment nginx --image=nginx
kubectl create deployment nginx --image=nginx --replicas=3

# Scale deployment
kubectl scale deployment nginx --replicas=5
kubectl autoscale deployment nginx --cpu-percent=50 --min=1 --max=10

# Update deployment
kubectl set image deployment/nginx nginx=nginx:1.20
kubectl rollout restart deployment/nginx

# Rollback deployment
kubectl rollout undo deployment/nginx
kubectl rollout undo deployment/nginx --to-revision=2
kubectl rollout history deployment/nginx

# Deployment status
kubectl rollout status deployment/nginx
kubectl get deployments
kubectl describe deployment nginx

Services​

# Create services
kubectl expose deployment nginx --port=80 --type=ClusterIP
kubectl expose deployment nginx --port=80 --type=NodePort
kubectl expose deployment nginx --port=80 --type=LoadBalancer

# List services
kubectl get services
kubectl get svc
kubectl describe service nginx

# Service endpoints
kubectl get endpoints
kubectl describe endpoints nginx

ConfigMaps and Secrets​

# ConfigMaps
kubectl create configmap app-config --from-literal=key1=value1
kubectl create configmap app-config --from-file=config.properties
kubectl get configmaps
kubectl describe configmap app-config

# Secrets
kubectl create secret generic app-secret --from-literal=password=secret123
kubectl create secret generic app-secret --from-file=credentials.txt
kubectl get secrets
kubectl describe secret app-secret

Container Security​

Security Best Practices​

# Scan images for vulnerabilities
docker scan image_name
trivy image nginx:latest

# Use non-root user
FROM nginx:alpine
RUN addgroup -g 1001 appgroup && \
    adduser -u 1001 -G appgroup -s /bin/sh -D appuser
USER appuser

# Security options
docker run --security-opt no-new-privileges nginx
docker run --read-only nginx
docker run --cap-drop ALL --cap-add NET_ADMIN nginx

Runtime Security​

# AppArmor profile
docker run --security-opt apparmor=profile_name nginx

# SELinux
docker run --security-opt label=level:s0:c100,c200 nginx

# Resource limits
docker run --memory=512m --cpus=1.0 nginx
docker run --ulimit nofile=1024:2048 nginx

# Network security
docker run --network none nginx      # No network access
docker run --dns 8.8.8.8 nginx      # Custom DNS

Virtual Machines​

KVM/QEMU​

# Install KVM
sudo apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virt-manager

# Check KVM support
kvm-ok
lscpu | grep Virtualization

# Create VM
qemu-img create -f qcow2 vm-disk.qcow2 20G
virt-install --name myvm --ram 2048 --disk path=vm-disk.qcow2,size=20 --cdrom ubuntu.iso

# Manage VMs
virsh list --all
virsh start myvm
virsh shutdown myvm
virsh destroy myvm
virsh undefine myvm

# VM information
virsh dominfo myvm
virsh vcpuinfo myvm
virsh domblklist myvm

VirtualBox​

# Install VirtualBox
sudo apt install virtualbox virtualbox-ext-pack

# Manage VMs
VBoxManage list vms
VBoxManage startvm "VM Name"
VBoxManage controlvm "VM Name" poweroff
VBoxManage controlvm "VM Name" pause
VBoxManage controlvm "VM Name" resume

# Create VM
VBoxManage createvm --name "MyVM" --register
VBoxManage modifyvm "MyVM" --memory 2048 --cpus 2
VBoxManage createhd --filename "MyVM.vdi" --size 20000
VBoxManage storagectl "MyVM" --name "SATA Controller" --add sata
VBoxManage storageattach "MyVM" --storagectl "SATA Controller" --port 0 --device 0 --type hdd --medium "MyVM.vdi"

Container Monitoring​

Docker Monitoring​

# Container resource usage
docker stats
docker stats --format "table {{.Container}}\t{{.CPUPerc}}\t{{.MemUsage}}"

# System-wide Docker info
docker system df              # Disk usage
docker system events          # Real-time events
docker system info            # System information

# Container inspection
docker inspect container_name | jq '.State'
docker inspect container_name | jq '.NetworkSettings.IPAddress'

Kubernetes Monitoring​

# Resource usage
kubectl top nodes
kubectl top pods
kubectl top pods --containers

# Cluster events
kubectl get events
kubectl get events --sort-by=.metadata.creationTimestamp

# Resource quotas
kubectl get resourcequota
kubectl describe resourcequota

Monitoring Tools​

# Prometheus configuration for containers
# docker-compose.yml
version: '3.8'
services:
  prometheus:
    image: prom/prometheus
    ports:
      - "9090:9090"
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml

  node-exporter:
    image: prom/node-exporter
    ports:
      - "9100:9100"

  cadvisor:
    image: gcr.io/cadvisor/cadvisor
    ports:
      - "8080:8080"
    volumes:
      - /:/rootfs:ro
      - /var/run:/var/run:ro
      - /sys:/sys:ro
      - /var/lib/docker/:/var/lib/docker:ro

Container Troubleshooting​

Common Issues and Solutions​

# Container won't start
docker logs container_name
docker inspect container_name | jq '.State'

# Permission issues
docker exec -it --user root container_name bash
docker run --privileged container_name

# Network connectivity
docker exec container_name ping google.com
docker exec container_name nslookup google.com
docker network ls
docker network inspect bridge

# Storage issues
docker exec container_name df -h
docker system df
docker volume ls

Debug Commands​

# Container filesystem
docker exec container_name find / -name "*.log"
docker exec container_name ls -la /proc/1/fd/

# Process debugging
docker exec container_name ps aux
docker exec container_name netstat -tuln
docker exec container_name lsof -i

# Performance debugging
docker exec container_name top
docker exec container_name iostat
docker exec container_name free -h

Recovery Operations​

# Restart services
docker-compose restart
kubectl rollout restart deployment/app

# Recover from failed state
docker container prune
docker volume prune
docker network prune
docker system prune -a

# Backup and restore
docker commit container_name backup_image
docker save -o backup.tar image_name
docker load -i backup.tar

Container Orchestration​

Docker Swarm​

# Initialize swarm
docker swarm init
docker swarm init --advertise-addr 192.168.1.100

# Join swarm
docker swarm join --token TOKEN manager-ip:2377
docker swarm join-token worker
docker swarm join-token manager

# Manage nodes
docker node ls
docker node inspect node-id
docker node update --availability drain node-id

# Deploy services
docker service create --name web --replicas 3 -p 8080:80 nginx
docker service ls
docker service ps web
docker service scale web=5
docker service update --image nginx:1.20 web

Kubernetes Advanced​

# StatefulSets
kubectl create -f statefulset.yaml
kubectl get statefulsets
kubectl scale statefulset mysql --replicas=3

# DaemonSets
kubectl get daemonsets
kubectl describe daemonset fluentd

# Jobs and CronJobs
kubectl create job hello --image=busybox -- echo "Hello World"
kubectl create cronjob hello --image=busybox --schedule="*/1 * * * *" -- echo "Hello World"

# Ingress
kubectl get ingress
kubectl describe ingress myapp-ingress

Container Performance​

Optimization Techniques​

# Multi-stage builds
FROM node:16 AS builder
WORKDIR /app
COPY package.json .
RUN npm install

FROM node:16-alpine
WORKDIR /app
COPY --from=builder /app/node_modules ./node_modules
COPY . .
CMD ["npm", "start"]

# Layer caching
COPY package.json .
RUN npm install
COPY . .

# Resource limits
docker run --memory=512m --cpus=1.0 nginx
docker run --oom-kill-disable nginx

Performance Monitoring​

# Container metrics
docker stats --no-stream
docker exec container_name cat /proc/meminfo
docker exec container_name cat /proc/cpuinfo

# Kubernetes metrics
kubectl top pods --sort-by=cpu
kubectl top pods --sort-by=memory
kubectl get hpa

Quick Reference​

Essential Commands​

# Docker basics
docker ps -a                    # List all containers
docker images                   # List images
docker exec -it container bash  # Access container shell
docker logs -f container        # Follow container logs

# Kubernetes basics
kubectl get pods                # List pods
kubectl get services            # List services
kubectl describe pod pod-name   # Pod details
kubectl logs pod-name           # Pod logs

# Cleanup
docker system prune -a          # Clean Docker system
kubectl delete pod --all        # Delete all pods
docker-compose down -v          # Stop and remove volumes

Common Troubleshooting​

# Container debugging
docker inspect container_name | jq '.State.Health'
docker exec container_name ps aux
docker exec container_name netstat -tuln

# Network issues
docker network ls
kubectl get svc
kubectl describe endpoints service-name

# Storage issues
docker volume ls
kubectl get pv
kubectl get pvc