Deploy SpringBoot web Application(tomcat server) to BTP Kyma runtime

One of customers ask if their existing application deployed in tomcat server can be deployed into BTP runtimes . I think one option is BTP cloud foundry runtime. I checked the document , BTP cloud foundry has tomcat container. The tutorial Create a Java Application via Cloud Foundry Command Line Interface | Tutorials for SAP Developers give guidance about how. I tried it and if I follow the steps , I can succeed .

Then I think why not build docker image for the application run in Tomcat server and then deply the application into BTP Kyma runtime. I tried with springboot web application run with Tomcat server.

In this blog, I will share the steps :

Prerequisites:

1, Have installed Java JDK

2, Have installed Maven

3, Have installed docker

4, Have installed Intellij IDEA(Optional)

5, Kyma runtime has been activated in your BTP subaccount .

Step 1: Creat a SpringBoot application name tomaop

The following is the POM file .

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.7.8</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
  <groupId>com.sap</groupId>
  <artifactId>tomaop2</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>tomaop2</name>
  <description>Demo project for Spring Boot</description>
  <properties>
    <java.version>11</java.version>
  </properties>
  <dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

</project>

The following is the controller class:

package com.sap.tomaop2.controller;
import com.sap.tomaop2.model.Employee;
import com.sap.tomaop2.service.EmployeeService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController

public class EmployeeController {

  @Autowired
  private  EmployeeService employeeService;

  @GetMapping(path = "/add/employee")
  public Employee createEmployee(@RequestParam("empId") String empId,@RequestParam("firstName") String firstName,@RequestParam("secondName") String secondName){
   return employeeService.createEmployee(empId,firstName,secondName);
  }
  @GetMapping(path = "/del/employee")
  public String deleteEmployee(@RequestParam("empId") String empId){
    employeeService.deleteEmployee(empId);
    return "The employe " + empId +" has been deleted";
  }
  
}

Run the application with the command: mvn spring-boot:run

Test in browser:

Step 2: Buid docker file for the SpringBoot application

Add google-jib plugin in pom file

Maintain docker account information in Intellij IDEA .

Run the following command to build the application:

mvn compile jib:buildTar

Check the generated tar file :

Load the tar file to Docker with following command:

docker load -i ./target/jib-image.tar

Check the image with the following command:

docker images | find “spring”

Push the image to docker hub with following command:

Step 3: Prepare Kyma deployment YAML file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomaop
  labels:
    app: tomaop
spec:
  selector:
    matchLabels:
      app: tomaop
  strategy:
    rollingUpdate:
      maxUnavailable: 1
  replicas: 1
  template:
    metadata:
      labels:
        app: tomaop
    spec:
      containers:
        - image: registry.hub.docker.com/dockeraccount/springbootaop:latest
          imagePullPolicy: Always
          name: tomaop
          ports:
            - name: http
              containerPort: 8080
          env:
            - name: DEBUG
              value: "true"
            - name: RENEWCERT_JOB_CRON
              value: "00 00 */12 * * *"
          resources:
            requests:
              memory: "512Mi"
              cpu: "50m"
            limits:
              memory: "1000Mi"
              cpu: "100m"
---
apiVersion: v1
kind: Service
metadata:
  name: tomaop
  labels:
    app: tomaop
spec:
  ports:
    - name: http
      port: 8080
  selector:
    app: tomaop