Skip to main content

Quick installation of Java Apps

First, make sure you have installed the following tools:

  • Docker
  • Maven

Step 1: Write Your Java Program

  • Open the project's pom.xml file and add the following content to the <dependencies> section to include the MySQL JDBC driver:

  • Next, add the following content to the file in the src/main/resources directory to configure the database connection:


Step 2: Create Entity and Repository Classes

Create a new Java class in the project, such as, to represent the entity in the database. Add the following content:

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

public class Person {
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String name;

// Getters and setters
// ...
  • Then create a repository interface, such as

    import org.springframework.stereotype.Repository;

    public interface PersonRepository extends JpaRepository<Person, Long> {

Step 3: Create a Web Controller

  • In the src/main/java directory of the project, create a simple web controller. For example, create a file named and add the following content:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

public class PersonController {
private PersonRepository personRepository;

public String getAllPersons() {
List<Person> persons = personRepository.findAll();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < persons.size(); i++) {
sb.append("id: " + persons.get(i).getId() + " name: " + persons.get(i).getName() + "/n");
return sb.toString();

@PostMapping(value = "/addPerson")
public Person addPerson(@RequestBody Person person) {


Step 4: Build the Application

  • Build the project using Maven by running the following command:

    mvn clean install

Step 5: Create a Docker Image

  • In the root directory of the Java project, create a file named Dockerfile. This file will contain the instructions required to build the Docker image. Here's a simple example Dockerfile:

    # Use the official OpenJDK image as the base image
    FROM openjdk:8-jre-slim

    # Set the working directory
    WORKDIR /app

    # Copy the built JAR file into the image
    COPY target/demo-0.0.1-SNAPSHOT.jar /app/demo-0.0.1-SNAPSHOT.jar

    # Expose the application's port
    EXPOSE 8080

    # Set the start command
    CMD ["java", "-jar", demo-0.0.1-SNAPSHOT.jar"]
  • In the project root directory, run the following command to build the Docker image:

docker build -t java-demo .

Step 6: Push the Docker Image

  • Push the created Docker image to a Docker repository, such as Docker Hub or a private repository. Assuming you are already logged in to the Docker repository, use the following command to push the image:

    • First, tag the Docker image. Before pushing an image, you need to add a tag to it so that Docker knows where to push it. Run the following command to add a tag to the image:

      docker tag your-image-name your-dockerhub-username/your-repo-name:your-tag

      Replace your-image-name with your local image name, your-dockerhub-username with your Docker Hub username, your-repo-name with the repository name you want to create on Docker Hub, and your-tag with the tag you set for the image (e.g., latest).

    • Then, push the tagged image to the Docker repository:

      docker push your-dockerhub-username/your-repo-name:your-tag

Step 7: Log in to Sealos

  • Visit the Sealos official website

Step 8: Open the "Database" application

Step 9: Create a database

  • Click on "Create New Database"

  • Basic configuration:
    • Cluster type: mysql
    • Cluster name: demo-db
    • CPU (recommended): 1 Core
    • Memory (recommended): 1 G
    • Number of instances: 1
    • Storage capacity: 1 Gi
  • Click "Deploy Cluster"

Step 10: Configure the database

  • Click on "One-click Connect to Database" and execute the following statements:

    • Create the test_db database

      create database test_db;
    • Create the test table

      CREATE TABLE `name_info` (
      `id` int(11) NOT NULL,
      `name` varchar(12) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
      PRIMARY KEY (`id`)
    • Insert data

      insert into test values (1,'Sealos');

Step 11: Open the "App Launchpad" application

Step 12: Create a new application

  • In "App Launchpad", click on "Create New Application" to create a new application.

Step 13: Deploy the application

  • Basic configuration:
    • Application name (custom): java-demo
    • Image name: damager6666/java-demo:v2
    • CPU (recommended): 1 Core
    • Memory (recommended): 1 G
  • Deployment mode:
    • Number of instances (custom): 1

  • Network configuration:
    • Exposed container port: 8080
    • Public network access: enabled

Step 14: Deploy the application

  • Click on "Deploy Application" to start deploying the application.

Step 15: Access the application

  • Click on "Application Management" to view the application. When the application's STATUS changes from Pending to Running, it indicates that the application has started successfully.
  • When the STATUS is Running, you can directly access the public network address.

  • Enter the following in your browser:

  • The page displays the data inserted into the database earlier, indicating that your Java application is now running on Sealos.