Docker Containerization: Building Images, Setting Up a Private Registry, and Deploying with Docker Compose

1. Benefits of Containerized Deployment

Docker, as a lightweight virtualization technology, utilizes system resources efficiently without the overhead of full hardware virtualization or a complete operating system.

Traditional virtual machines take minutes to start, whereas Docker containers start in seconds or milliseconds because they share the host kernel, dramatically reducing development, testing, and deployment time.

The most important benefit is a consistent runtime environment; Docker images contain the full runtime (except the kernel), ensuring "build once, run anywhere".

2. Building the Image

2.1 Dockerfile

We create a Dockerfile to define a custom image. The Dockerfile combines a series of commands for modifications, installations, and builds, achieving the "build once, run anywhere" goal.

In the my-project-server module, create a docker directory and add the following Dockerfile:

FROM openjdk:8-jre

MAINTAINER Micromaple
RUN mkdir /app

COPY my-project-server-1.0.0-SNAPSHOT.jar /app/app.jar

ENTRYPOINT ["java", "-Djava.security.egd=file:/dev/./urandom", "-jar", "/app/app.jar", "--spring.profiles.active=prod,druid-prod"]

EXPOSE 8899

FROM : base image (openjdk:8-jre).

MAINTAINER : project maintainer.

RUN : create /app directory.

COPY : copy my-project-server-1.0.0-SNAPSHOT.jar to /app/app.jar .

ENTRYPOINT : start the Java application with parameters.

EXPOSE : expose port 8899.

2.2 Start Building

Create a directory on the VM and place the built JAR and Dockerfile there:

mkdir -p /usr/local/docker/my-project/docker

Build the image:

docker build -t my-project-server:v1 .

Verify the image:

$ docker images
REPOSITORY          TAG   IMAGE ID       CREATED          SIZE
my-project-server  v1    ed30386b06d2   11 seconds ago   334MB
openjdk             8-jre 26ac3f63d29f   9 months ago     273MB

3. Setting Up a Private Registry

3.1 Docker Registry

Create the registry directory:

mkdir -p /usr/local/docker/registry

Create docker-compose.yml :

version: '3.1'
services:
  registry:
    image: registry
    restart: always
    container_name: registry
    ports:
      - 5000:5000
    volumes:
      - ./data:/var/lib/registry

Start the registry container:

docker-compose up -d

3.2 Docker Registry Web UI

Create the UI directory and its docker-compose.yml :

mkdir -p /usr/local/docker/docker-registry-frontend
cd /usr/local/docker/docker-registry-frontend

version: '3.1'
services:
  frontend:
    image: konradkleine/docker-registry-frontend:v2
    ports:
      - 8080:80
    volumes:
      - ./certs/frontend.crt:/etc/apache2/server.crt:ro
      - ./certs/frontend.key:/etc/apache2/server.key:ro
    environment:
      - ENV_DOCKER_REGISTRY_HOST=192.168.110.158
      - ENV_DOCKER_REGISTRY_PORT=5000

After editing ENV_DOCKER_REGISTRY_HOST to your registry IP, start the UI:

docker-compose up -d

Access it at http://192.168.110.158:8080/ .

3.3 Client Configuration

Edit /etc/docker/daemon.json to trust the private registry:

{
  "registry-mirrors": ["https://xxx.mirror.aliyuncs.com"],
  "insecure-registries": ["192.168.110.158:5000"]
}

Reload and restart Docker:

systemctl daemon-reload
systemctl restart docker

3.4 Uploading the Image

Tag the image for the private registry:

docker tag my-project-server:v1 192.168.110.158:5000/my-project-server:v1

Push it:

docker push 192.168.110.158:5000/my-project-server

Verify with curl:

curl 192.168.110.158:5000/v2/_catalog
{"repositories":["my-project-server"]}

4. Container Startup

Create a directory for the application and a docker-compose.yml that pulls the image from the private registry:

mkdir -p /usr/local/docker/my-project
cd /usr/local/docker/my-project

version: '3.1'
services:
  my_project_server:
    image: 192.168.110.158:5000/my-project-server:v1
    container_name: my-project-server
    restart: always
    ports:
      - 8899:8899
    volumes:
      - ./logs:/logs
    environment:
      TZ: Asia/Shanghai

Start the container:

docker-compose up -d

Check status with docker ps -a and access the service (e.g., http://192.168.110.158:8899/sys-user/get/all ).