How to Set Up Docker on CentOS and Deploy a Spring Boot App in Containers

Environment: SpringBoot2.6.12 + Docker + Centos7 + JDK8

1. Install and configure Docker

Update yum packages to the latest version. yum update Remove any old Docker versions.

yum remove docker docker-common docker-selinux docker-engine

Install required utilities for yum-config-manager and device‑mapper.

yum install -y yum-utils device-mapper-persistent-data lvm2

Add the Docker yum repository.

yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

List all available Docker CE versions.

yum list docker-ce --showduplicates | sort -r

Install Docker CE. yum install docker-ce Start the Docker service. systemctl start docker Verify the Docker version.

docker version

2. Install docker‑compose (optional)

Download docker‑compose binary.

curl -L "https://github.com/docker/compose/releases/download/1.29.2/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

Add execution permission. chmod +x /usr/local/bin/docker-compose Create a symbolic link.

ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose

Verify the version. docker-compose --version Search for a Tomcat image.

docker search tomcat

Pull the Tomcat image.

docker pull tomcat

3. Deploy the Spring Boot project

Create a Spring Boot project named spring-boot-docker and add the following dependencies in pom.xml:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

Add a simple controller:

@RestController
@RequestMapping("/demo")
public class DemoController {
    @GetMapping("/index")
    public Object index() {
        return "docker container running...";
    }
}

Define the main application class:

@SpringBootApplication
public class SpringBootDockerApplication extends SpringBootServletInitializer {
    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        return builder.sources(SpringBootDockerApplication.class);
    }
    public static void main(String[] args) {
        SpringApplication.run(SpringBootDockerApplication.class, args);
    }
}

Package the application: mvn clean package -Dmaven.test.skip=true Upload the generated JAR/WAR to the server (illustrated below).

Run the container with the packaged artifact. Example for a WAR on Tomcat:

docker run -d --name demo-server -v /root/apps/spring-boot-docker-1.0.0.war:/usr/local/tomcat/webapps/spring-boot-docker-1.0.0.war -p 8080:8080 tomcat

Key options:

-v : mount the project file into the container

-p : map host port to container port (host:container)

-d : run in detached (background) mode

--name : assign a name to the container

tomcat : the image used

Check running containers:

docker ps

If you prefer to run the JAR directly, pull an OpenJDK image and mount the JAR:

docker run -d --name demo-server -v /root/apps/spring-boot-docker-1.0.0.jar:/usr/spring-boot-docker-1.0.0.jar -p 8081:8080 openjdk java -jar /usr/spring-boot-docker-1.0.0.jar

After the container starts, you can access the endpoint http://<host>:8080/demo/index and see the message "docker container running..." indicating a successful deployment.