Using Containerization

🎯 Exam Objectives

🎯

Exam Objective 1.6: Compare and contrast containerization concepts.

Track your learning progress! Click each objective as you master it:

Understand container architecture vs virtual machines
Master the container workflow: config → image → running container
Use Docker commands for container management
Deploy containers using cloud registries
Configure port mapping and storage types

📦 Containers vs Virtual Machines

Containers offer a different form of virtualization from VMs. While VMs virtualize hardware, containers virtualize the operating system, making them lightweight and portable.

🖥️ Virtual Machines

Virtualizes hardware
Includes full guest OS
Heavyweight (GBs)
Boot time: Minutes
Strong isolation

📦 Containers

Virtualizes OS
Shares single OS kernel
Lightweight (MBs)
Boot time: Seconds
Process-level isolation

💡 Container Characteristics: Containers are complete, portable solutions containing application code, runtime, libraries, and settings. They are lightweight, share a single OS (usually Linux), and provide a single function.

🔄 Container Lifecycle Workflow

Click each stage to understand the container creation process:

📄

Configuration File

Dockerfile with instructions

→

🖼️

Container Image

Built template (docker build)

→

Running Container

Executing instance (docker run)

Configuration File (Dockerfile): This text file contains everything necessary for the container to function: source code, libraries, tools, dependencies, etc. Think of this as a specifications sheet or set of instructions. The container engine processes this file to build the image.

Docker Workflow Example

# Step 1: Build image from Dockerfile

$ docker build -t myapp:latest .

# Step 2: Run container from image

$ docker run -d -p 8080:80 myapp:latest

# Step 3: Check running containers

$ docker ps

⌨️ Docker Command Reference

The docker command is the primary management tool. Here are essential commands:

Core Docker Commands

Command	Description	Example
docker pull	Pull an image from a registry	docker pull alpine
docker run	Run a command in a container	docker run -it alpine bash
docker ps	List containers	docker ps -a
docker images	List images	docker images
docker rm	Remove containers	docker rm container-id
docker rmi	Remove images	docker rmi image-name

Container Management Commands

Command	Description
docker container start	Start a stopped container
docker container stop	Stop a started container
docker container restart	Restart a container
docker container logs	Display container logs
docker container inspect	Display detailed container information

🗄️ 6.11 Image Registries

Container image registries are storage repositories for container images. They integrate with DevOps and CI/CD processes, allowing orchestration to pull images on the fly.

🌐

Docker Hub

Public Registry: Convenient, cost-effective, and straightforward. Perfect for getting started and accessing common images like Alpine, Python, or Nginx.

🔒

Private Registry

Enterprise Solution: On-premises or private cloud. Better for maintaining images, securing resources, and maintaining control over proprietary applications.

☁️

Cloud Registries

Cloud-Native: AWS ECR, Azure Container Registry, Google Artifact Registry. Integrates container storage with cloud-based infrastructure.

✅ Registry Advantages: Scalability, Security, Management Control, and Automation/Orchestration Integration.

☁️ 6.12 Containers in the Cloud

Cloud container services provide scalability, metered services, high availability, and reduced management overhead compared to on-premises solutions.

🛠️ Cloud Container Services

Amazon ECS: Run, monitor, and scale apps with AWS integration
Azure Kubernetes Service: Run containers on Kubernetes
Google Compute Engine: Manage containers on Kubernetes/Docker

📋 Deployment Steps

Create container instance
Name and select region
Choose image from registry
Select CPU/Memory size
Configure networking
Tag for billing

🔧 6.13 Container Management

Port Mapping

Port mapping associates container ports with host ports, providing access between the container and external networks.

External Client

Port 8080

→

️

Host System

Port 8080

→

Container

Port 80 (Nginx)

Port Mapping Example

# Map host port 8080 to container port 80

$ docker run -d -p 8080:80 nginx

# Now accessible at http://localhost:8080

Storage Types

Containers support two main storage types. Click each to learn more:

Non-permanent storage tied to the container's lifecycle. Created and removed along with the container.

Use Cases:

Data caching
Container logging
Temporary scratch space

Independent of the container's lifecycle. Stores data even if the container is stopped or deleted. Necessary for stateful applications.

Implementation:

Persistent storage volumes point to actual storage media
Can be statically or dynamically configured
Shared across container clusters (e.g., AWS EKS + EFS)

Orchestration

Container workload orchestration enables large-scale management using DevOps approaches. It provides:

Efficient deployments Automated management Scheduling Increased scalability High availability

Automation Integration: Automation helps configure port mapping and ephemeral/persistent storage as part of larger orchestrated management processes.