Container Management

Complete guide for managing Docker containers in NazDocker Lab.

💾 Volume Management

Separate Volume Structure

The lab environment uses separate volumes for Alpine and Ubuntu containers to ensure complete isolation and prevent data conflicts:

data/
├── alpine/           # Alpine container data
│   ├── admin/        # Admin user data (Alpine)
│   ├── user1/        # User1 data (Alpine)
│   ├── user2/        # User2 data (Alpine)
│   ├── user3/        # User3 data (Alpine)
│   ├── user4/        # User4 data (Alpine)
│   └── user5/        # User5 data (Alpine)
└── ubuntu/           # Ubuntu container data
    ├── admin/        # Admin user data (Ubuntu)
    ├── user1/        # User1 data (Ubuntu)
    ├── user2/        # User2 data (Ubuntu)
    ├── user3/        # User3 data (Ubuntu)
    ├── user4/        # User4 data (Ubuntu)
    └── user5/        # User5 data (Ubuntu)

logs/
├── alpine/           # Alpine container logs
└── ubuntu/           # Ubuntu container logs

Benefits of Separate Volumes

  • 🔒 Complete Isolation: Alpine and Ubuntu containers have completely separate data storage
  • 🚀 Concurrent Operation: Both container types can run simultaneously without conflicts
  • 📦 Easy Management: Backup, restore, or manage data for each container type separately
  • 🧹 Clean Organization: Clear separation makes it obvious which data belongs to which container
  • 🔄 Independent Scaling: Scale Alpine and Ubuntu environments independently

Volume Usage

  • Alpine Container: Stores data in ./data/alpine/ and logs in ./logs/alpine/
  • Ubuntu Container: Stores data in ./data/ubuntu/ and logs in ./logs/ubuntu/

🚀 Essential Commands

Ubuntu Version 

# Start the environment
docker-compose -f docker-compose.ubuntu.yml up -d

# Stop the environment
docker-compose -f docker-compose.ubuntu.yml down

# Restart the environment
docker-compose -f docker-compose.ubuntu.yml restart

# View logs
docker-compose -f docker-compose.ubuntu.yml logs -f

# Access container shell
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu bash

# Validate configuration
docker-compose -f docker-compose.ubuntu.yml config

# Check container status
docker-compose -f docker-compose.ubuntu.yml ps

Alpine Version (82% smaller) 

# Start the environment
docker-compose -f docker-compose.alpine.yml up -d

# Stop the environment
docker-compose -f docker-compose.alpine.yml down

# Restart the environment
docker-compose -f docker-compose.alpine.yml restart

# View logs
docker-compose -f docker-compose.alpine.yml logs -f

# Access container shell
docker-compose -f docker-compose.alpine.yml exec lab-environment-alpine bash

# Validate configuration
docker-compose -f docker-compose.alpine.yml config

# Check container status
docker-compose -f docker-compose.alpine.yml ps

📊 Container Monitoring

Status Checks

Ubuntu Version 

# Check container status
docker-compose -f docker-compose.ubuntu.yml ps

# Check resource usage
docker stats student-lab-ubuntu

# Check container logs
docker-compose -f docker-compose.ubuntu.yml logs lab-environment-ubuntu

# Check container health
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu systemctl status ssh

# Monitor health check status
docker ps --format "table \t\t"

# View health check configuration
docker inspect student-lab-ubuntu | grep -A 10 "Healthcheck"

Alpine Version 

# Check container status
docker-compose -f docker-compose.alpine.yml ps

# Check resource usage
docker stats student-lab-alpine

# Check container logs
docker-compose -f docker-compose.alpine.yml logs lab-environment-alpine

# Check container health
docker-compose -f docker-compose.alpine.yml exec lab-environment-alpine pgrep sshd

# Monitor health check status
docker ps --format "table \t\t"

# View health check configuration
docker inspect student-lab-alpine | grep -A 10 "Healthcheck"

Resource Monitoring 

# Monitor CPU and memory usage
docker stats --format "table \t\t\t\t"

# Check disk usage
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu df -h

# Check memory usage
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu free -h

🔧 Container Operations

View Running Containers 

# View running containers
docker ps

# View all containers (including stopped)
docker ps -a

# View container logs
docker-compose -f docker-compose.ubuntu.yml logs lab-environment-ubuntu

# Execute command in container
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu <command>

# Stop and remove everything
docker-compose -f docker-compose.ubuntu.yml down -v --remove-orphans

# Check container health status
docker ps --format "table \t\t"

# View detailed health information
docker inspect student-lab-ubuntu | grep -A 20 "Health"

Building Images 

# Build Ubuntu image
docker-compose -f docker-compose.ubuntu.yml build

# Build Alpine image
docker-compose -f docker-compose.alpine.yml build

# Build both images
docker-compose -f docker-compose.ubuntu.yml build && docker-compose -f docker-compose.alpine.yml build

# Force rebuild (no cache)
docker-compose -f docker-compose.ubuntu.yml build --no-cache

Running Both Containers Simultaneously

With separate volumes, you can run both Alpine and Ubuntu containers at the same time:

# Start both environments
docker-compose -f docker-compose.ubuntu.yml up -d
docker-compose -f docker-compose.alpine.yml up -d

# Access Ubuntu lab (port 2222)
ssh admin@localhost -p 2222

# Access Alpine lab (port 2223 - you'll need to modify SSH_PORT in .env)
ssh admin@localhost -p 2223

# Both containers use the same SSH host keys
# Stop both environments
docker-compose -f docker-compose.ubuntu.yml down
docker-compose -f docker-compose.alpine.yml down

🏥 Health Monitoring

Health Check Overview

The container includes built-in health checks that monitor SSH service availability:

  • Interval: 30 seconds between checks
  • Timeout: 10 seconds maximum for each check
  • Start Period: 40 seconds grace period after container startup
  • Retries: 3 consecutive failures before marking as unhealthy

Health Status Monitoring 

# Check container health status
docker ps --format "table \t\t"

# View detailed health information
docker inspect student-lab | grep -A 20 "Health"

# Monitor health check logs
docker inspect student-lab | grep -A 10 "Healthcheck"

# Test health check manually
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu service ssh status

Health Check Troubleshooting 

# If container shows as unhealthy
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu service ssh status

# Restart SSH service if needed
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu service ssh restart

# Check SSH configuration
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu cat /etc/ssh/sshd_config

# View health check logs
docker inspect student-lab-ubuntu | grep -A 20 "Health"

🔄 Container Lifecycle

Startup Process

  1. Container Creation: Docker creates container from image
  2. Startup Script: start.sh executes to configure users and services
  3. SSH Service: SSH daemon starts and begins accepting connections
  4. Health Checks: Health monitoring begins after grace period
  5. Ready State: Container is ready for connections

Shutdown Process

  1. Graceful Shutdown: Docker sends SIGTERM signal
  2. Service Stop: SSH service stops gracefully
  3. Data Persistence: User data in volumes is preserved
  4. Container Removal: Container is removed (unless using --rm)

🛠️ Advanced Operations

Container Inspection 

# View container details
docker inspect student-lab-ubuntu

# View container configuration
docker inspect student-lab-ubuntu | grep -A 10 "Config"

# View container network settings
docker inspect student-lab-ubuntu | grep -A 20 "NetworkSettings"

# View container mounts
docker inspect student-lab-ubuntu | grep -A 10 "Mounts"

Container Debugging 

# Access container with custom shell
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu /bin/bash

# Run command in container
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu whoami

# Copy files to/from container
docker cp student-lab-ubuntu:/etc/ssh/sshd_config ./sshd_config_backup
docker cp ./custom_script.sh student-lab-ubuntu:/tmp/

# View container logs in real-time
docker-compose -f docker-compose.ubuntu.yml logs -f --tail=100

Performance Optimization 

# Monitor resource usage
docker stats --no-stream

# Check container performance
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu top

# Monitor disk I/O
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu iostat

# Check network connectivity
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu ping google.com

🧹 Cleanup Operations

Complete Cleanup 

# Stop and remove everything
docker-compose -f docker-compose.ubuntu.yml down -v --remove-orphans --rmi all

# Remove all unused Docker resources
docker system prune -a --volumes

# Verify cleanup
docker ps -a
docker network ls
docker volume ls
docker images

Selective Cleanup 

# Remove specific resources
docker rm -f student-lab-ubuntu
docker network rm nazdocker-lab_lab-network
docker volume rm nazdocker-lab_user-data

# Remove unused images
docker image prune -a

# Remove unused volumes
docker volume prune

📝 Management Scripts

Status Check Script 

#!/bin/bash
# status-check.sh

echo "=== NazDocker Lab Status ==="
echo "Container Status:"
docker-compose -f docker-compose.ubuntu.yml ps
echo ""

echo "Health Status:"
docker ps --format "table \t\t"
echo ""

echo "Recent Logs:"
docker-compose -f docker-compose.ubuntu.yml logs --tail=20 lab-environment-ubuntu
echo ""

echo "Resource Usage:"
docker stats --no-stream student-lab-ubuntu
echo ""

echo "User Accounts:"
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu bash -c "cat /etc/passwd | grep -E ':(/bin/bash|/bin/sh)$'"

Health Monitoring Script 

#!/bin/bash
# health-monitor.sh

echo "=== NazDocker Lab Health Monitor ==="
echo ""

echo "Container Health Status:"
docker ps --format "table \t\t"
echo ""

echo "Detailed Health Information:"
docker inspect student-lab-ubuntu | grep -A 20 "Health"
echo ""

echo "SSH Service Status:"
docker-compose -f docker-compose.ubuntu.yml exec lab-environment-ubuntu service ssh status
echo ""

echo "Recent Health Check Logs:"
docker inspect student-lab-ubuntu | grep -A 10 "Healthcheck"

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