Docker Beginner Guide: Installation, Core Concepts, Image & Container Management, Registry Setup, and Docker Compose

This article provides a step‑by‑step introduction to Docker, covering installation, basic commands, core concepts, and advanced usage scenarios.

1. Docker Installation and First Run

Prepare a CentOS 7 64‑bit system with kernel version 3.10 or higher, then install Docker with:

yum -y install docker-io

Start the daemon:

service docker start

Run a test Nginx container:

docker run -p 80:80 -d nginx

2. Docker Theory

Docker uses lightweight containers (similar to shipping containers) instead of full virtual machines, providing process‑level isolation, fast startup, and low overhead.

Key components:

Docker daemon (dockerd) : Manages images, containers, networks, and volumes.

REST API : Enables client‑server communication.

Docker CLI : Command‑line interface for interacting with the daemon.

Image : Read‑only template that can be layered.

Container : Runtime instance created from an image.

Registry : Stores and distributes images (Docker Hub, Alibaba Cloud, private registries).

3. Image Management

Common image commands:

docker images          # list local images
docker search mysql   # search remote registry
docker pull mysql:5.7 # download image
docker rmi
# remove image

Configure a mirror for faster pulls (CentOS example):

{
  "registry-mirrors": ["https://uqxmqcrw.mirror.aliyuncs.com"]
}

4. Dockerfile Basics

A Dockerfile defines how to build a custom image. Example:

# Base image
FROM java:8
# Maintainer
MAINTAINER jackly
# Add application JAR
ADD eureka-server-0.0.1-SNAPSHOT.jar /app/service/eureka/data/app.jar
# Expose port
EXPOSE 8761
# Startup command
ENTRYPOINT ["java","-jar","/app/service/eureka/data/app.jar"]

Build and run the image:

docker build -t registry-jackly/eureka-server:1.0.0 .
docker run -d -p 8761:8761 --name=eureka registry-jackly/eureka-server:1.0.0

5. Container Lifecycle & Management

Typical container commands:

docker run -d -p 5000:5000 --name=registry-local-jackly registry
docker ps -a               # list containers
docker stop
docker start
docker exec -it
/bin/bash   # interactive shell
docker commit -m "add ll" -a "jackly"
registry-jackly/eureka-server:2.0.0

6. Networking

Expose services with -p hostPort:containerPort or random ports with -P . Containers on the same user‑defined network can communicate via their names.

7. Data Sharing (Volumes)

Mount host directories into containers:

docker run -d -p 8761:8761 -v /app/service/eureka/logs:/opt/data --name=eureka registry-jackly/eureka-server:2.0.0

Note: VOLUME in a Dockerfile creates an anonymous volume; the host path is managed by Docker under /var/lib/docker/volumes/ .

8. Private Registry Setup

Generate RSA certificates, run a registry container, and optionally a web UI:

# Generate cert
openssl req -new -newkey rsa:4096 -days 365 -subj "/CN=localhost" -nodes -x509 -keyout conf/auth.key -out conf/auth.cert
# Run registry
docker run -v /app/registry-jackly/conf/registry-jackly.yml:/etc/docker/registry/config.yml:ro \
  -v /app/registry-jackly/conf/auth.cert:/etc/docker/registry/auth.cert:ro \
  -p 5000:5000 --name registry-docker -d registry

9. Maven Docker Plugin

Configure the Spotify Docker Maven plugin to build and push images directly from the Maven lifecycle.

<plugin>
  <groupId>com.spotify</groupId>
  <artifactId>docker-maven-plugin</artifactId>
  <version>1.1.1</version>
  <configuration>
    <registryUrl>registry-docker:5000</registryUrl>
    <dockerHost>http://registry-docker:2375</dockerHost>
    <imageName>registry-docker:5000/${project.artifactId}:${project.version}</imageName>
    <baseImage>java:8</baseImage>
    <entryPoint>["java","-jar","/${project.build.finalName}.jar"]</entryPoint>
    <pushImage>true</pushImage>
  </configuration>
</plugin>

10. Docker Compose for a Spring Cloud Stack

Define services (eureka, config, zipkin, ELK, microservices, MySQL, Zuul) in separate docker-compose.yml files and launch them with:

docker-compose -f docker-compose-eureka.yml up -d
docker-compose -f docker-compose-config.yml up -d
... (other services)

Example of a service definition:

version: '3'
services:
  eureka:
    container_name: eureka
    image: registry-docker:5000/eureka-server:1.0.0
    ports:
      - "8761:8761"
    volumes:
      - /app/service/eureka/logs:/opt/data
    privileged: true
    networks:
      - default
networks:
  default:
    external:
      name: dockernet

After deployment you can access the registry UI, ELK Kibana, Zipkin UI, and the various microservice endpoints (e.g., http:// :8761/ , http:// :8083/product/findAllProduct ).