From Code To Online Services: My experiments of DevOps - Development of RESTful Web Services by Spring Boot, Jersey, Swagger

1. The Stack of Frameworks / Specs

Well, even any application can be built and used for this experiment, but why not build an interesting one: a real world RESTful service by saying hello to someone? Alright, that’s just another statement for a hello world application;)

Here we go:

Sprint Boot: The fundamental framework for the services.
Jersey: The RI of JAX-RS specs.
Swagger: The API documentation specs and tooling.
For testing, we’re going to use

Spring Boot Test Framework (spring-boot-starter-test) with Junit, Hamcrest
Rest Assured

2. Git Server: Gogs

Even we can setup Git Server later, but as version control is important, please do it as early as possible.

Note: I did try GitLab but: 1) it’s too slow running in my laptop; and 2) I was facing several permission issues being thrown from embedded Nginx…so I changed my mind and had Gogs instead as it’s really “a painless self-hosted Git service” as advertised.

2.1 Spin Up the Docker Container

$ cd ~
$ mkdir cd_demo
$ cd cd_demo
$ touch docker-compose.yml
$ vim docker-compose.yml

Gogs:
  image: 'gogs/gogs:latest'
  ports:
    - '3000:3000'
    - '1022:22'
  volumes:
    - '/data/gogs:/data'

Note: it’s a good practice to mount a local path (here is /data) for the container so all valuable data like settings, database will not be gone even we upgrade our container.

$ docker-compose up

Now, we have spun up our first Docker container for Gogs, our Git server.

2.2 Configuration

In just a few seconds, the Gogs container should have been up and running and we can access the app by: http://192.168.56.118:3000

It would guide us for the “Install Steps For First-time Run”.

Below were my inputs, for your reference:

Database Settings

Database Type: SQLite3
Path: /data/db/gogs.db

Application General Settings

Application Name: Gogs: Go Git Service
Repository Root Path: /data/git/gogs-repositories
Run User: git
Domain: 192.168.56.118
SSH Port: 22
HTTP Port: 3000
Application URL: http://192.168.56.118:3000/
Log Path: data/log

Optional Settings

Admin Account Settings: omitted

Once done, Gogs will persistent the settings and redirect to the home page.

2.3 Create Our First Repository

All these can be done via Gogs UIs:

Gogs - New Repository for Spring Boot, Jersey, Swagger

2.4 Clone the Git Repository to Kick Off Development

By command line, it’s very simple and straightforward.

Open Git Bash and key in:

$ git clone http://192.168.56.118:3000/bright/springboot-jersey-swagger.git

Or we can do it by using Eclipse if you prefer to.

3. Create Maven-based Project Structure

Since development part is my strongest part and code says more than words, let’s make it short but clear during the experiment.

Apparently, as we follow Maven’s best practices to build the project so the folder structure is exactly Maven-driven:

---------------------------------------------

│ LICENSE

│ pom.xml

│ README.md

├───src

│ ├───main

│ │ ├───java

│ │ │ └───bright

│ │ │ └───zheng

│ │ │ └───poc

│ │ │ └───api

│ │ │ │ ApiApplication.java

│ │ │ ├───config

│ │ │ │ JerseyConfig.java

│ │ │ ├───model

│ │ │ │ Hello.java

│ │ │ └───resources

│ │ │ HelloResource.java

│ │ └───resources

│ │ │ application.yml

│ │ │ bootstrap.yml

│ │ │ log4j.xml

│ │ ├───static

│ └───test

│ └───java

│ └───bright

│ └───zheng

│ └───poc

│ └───api

│ ApplicationTests.java

---------------------------------------------

Meanwhile, I’ll highlight some important files with necessary comments so that we can easily understand how to develop a RESTful application by using abovementioned frameworks.

3.1 pom.xml

/pom.xml

<?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 http://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>1.3.5.RELEASE</version>
              <relativePath />
       </parent>

       <groupId>bright.zheng.poc.api</groupId>
       <artifactId>springboot-jersey-swagger</artifactId>
       <version>1.0.0-SNAPSHOT</version>
       <packaging>jar</packaging>

       <name>springboot-jersey-swagger-docker</name>
       <description>POC - Restful API by Spring Boot, Jersey, Swagger</description>


       <properties>
              <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
              <java.version>1.8</java.version>
             
              <!-- project related properties -->
              <start-class>bright.zheng.poc.api.ApiApplication</start-class>
              <swagger-jersey2-jaxrs>1.5.3</swagger-jersey2-jaxrs>
              <rest-assured>3.0.0</rest-assured>
       </properties>

       <dependencies>
              <dependency>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-starter-actuator</artifactId>
              </dependency>
              <dependency>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-starter-jersey</artifactId>
              </dependency>
              <dependency>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-starter-web</artifactId>
              </dependency>
              <dependency>
                     <groupId>io.swagger</groupId>
                     <artifactId>swagger-jersey2-jaxrs</artifactId>
                     <version>${swagger-jersey2-jaxrs}</version>
              </dependency>

              <!-- testing related dependencies -->
              <dependency>
                     <groupId>org.springframework.boot</groupId>
                     <artifactId>spring-boot-starter-test</artifactId>
                     <scope>test</scope>
              </dependency>
              <dependency>
                     <groupId>io.rest-assured</groupId>
                     <artifactId>rest-assured</artifactId>
                     <version>${rest-assured}</version>
                     <scope>test</scope>
              </dependency>
       </dependencies>

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

3.2 ApiApplication.java

\src\main\java\bright\zheng\poc\api\ApiApplication.java

package bright.zheng.poc.api;


import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.context.web.SpringBootServletInitializer;

/**
 * This is a typical boostrap class for Spring Boot based application
 * 
 * @author bright.zheng
 *
 */
@SpringBootApplication
public class ApiApplication
extends SpringBootServletInitializer {  
       @Override
       protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
            return builder.sources(ApiApplication.class);
       }

       public static void main(String[] args) {
              SpringApplication.run(ApiApplication.class, args);
       }
}

3.3 HelloResource.java

\src\main\java\bright\zheng\poc\api\resources\HelloResource.java

package bright.zheng.poc.api.resources;

import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import bright.zheng.poc.api.model.Hello;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import io.swagger.annotations.ApiParam;
import io.swagger.annotations.ApiResponse;
import io.swagger.annotations.ApiResponses;

@Component
@Path("/v1/hello")
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
@Api(value = "Hello API - say hello to the world", produces = "application/json")
public class HelloResource {

       private static final Logger LOGGER = LoggerFactory.getLogger(HelloResource.class);

       @GET                                     //JAX-RS Annotation
       @Path("/{name}")     //JAX-RS Annotation
       @ApiOperation(                           //Swagger Annotation
                     value = "Say hello by providing the name by URI, via standard json header",
                     response = Hello.class) 
       @ApiResponses(value = {           //Swagger Annotation
              @ApiResponse(code = 200, message = "Resource found"),
           @ApiResponse(code = 404, message = "Resource not found")
       })
       public Response sayHelloByGet(@ApiParam @PathParam("name") String name) {
              LOGGER.info("v1/hello/{} - {}", name, MediaType.APPLICATION_JSON);
              return this.constructHelloResponse(name, MediaType.APPLICATION_JSON);
       }
      
       ///////////////////////////////////////////////////////////////

       private Response constructHelloResponse(String name, String via) {
              //for testing how we handle 404
              if ("404".equals(name)) {
                     return Response.status(Status.NOT_FOUND).build();
              }
              Hello result = new Hello();
              result.setMsg(String.format("Hello %s - %s", name, via));
              return Response.status(Status.OK).entity(result).build();
       }
}

3.4 JerseyConfig.java

\src\main\java\bright\zheng\poc\api\config\JerseyConfig.java

package bright.zheng.poc.api.config;

import javax.annotation.PostConstruct;

import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.server.wadl.internal.WadlResource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import bright.zheng.poc.api.resources.HelloResource;
import io.swagger.jaxrs.config.BeanConfig;
import io.swagger.jaxrs.listing.ApiListingResource;
import io.swagger.jaxrs.listing.SwaggerSerializers;

/**
 * Jersey Configuration
 *
 * <p>
 *
 * The endpoint will expose not only the real APIs,
 * but also two important documents:
 * <li> - swagger spec: /swagger.json</li>
 * <li> - WADL spec: /application.wadl</li>
 *
 * </p>
 *
 * @author bright.zheng
 *
 */
@Component
public class JerseyConfig extends ResourceConfig {

       @Value("${spring.jersey.application-path:/api}")
       private String apiPath;

       public JerseyConfig() {
              this.registerEndpoints();
       }
      
       @PostConstruct
       public void init() {
              this.configureSwagger();
       }

       private void registerEndpoints() {
              this.register(HelloResource.class);
              this.register(WadlResource.class);
       }

       private void configureSwagger() {
              this.register(ApiListingResource.class);
              this.register(SwaggerSerializers.class);

              BeanConfig config = new BeanConfig();
              config.setTitle("POC - Restful API by Spring Boot, Jersey, Swagger");
              config.setVersion("v1");
              config.setContact("Bright Zheng");
              config.setSchemes(new String[] { "http", "https" });
              config.setBasePath(this.apiPath);
              config.setResourcePackage("bright.zheng.poc.api.resources");
              config.setPrettyPrint(true);
              config.setScan(true);
       }

}

4. Swagger UI Integration

It would be great to have Swagger UI integration for automatic API documentation.

Simply do below steps:

Download it from https://github.com/swagger-api/swagger-ui/archive/master.tar.gz. As of writing, the latest version is v2.1.4.

Unzip it and copy all the files to folder: /src/main/resources/static/

5. Testing

Programmers write unit tests, of course. Here we go:

5.1 ApplicationTests.java

\src\test\java\bright\zheng\poc\api\ApplicationTests.java

package bright.zheng.poc.api;

import static io.restassured.RestAssured.expect;
import static org.hamcrest.Matchers.containsString;
import static org.hamcrest.Matchers.equalTo;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.test.SpringApplicationConfiguration;
import org.springframework.boot.test.WebIntegrationTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import io.restassured.RestAssured;

/**
 * Application level testing
 *
 * @author bright.zheng
 *
 */
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = ApiApplication.class)
@WebIntegrationTest({"server.port=0"})
public class ApplicationTests {
      
    @Value("${local.server.port}")
    private int port;
      
    @Before
    public void setupURL() {
        RestAssured.baseURI = "http://localhost";
        RestAssured.port = port;
        RestAssured.basePath = "/";
    }
 
    /**
     *
     * {"app":{"name":"springboot-jersey-swagger"},"build":{"version":"1.0.0-SNAPSHOT"}}
     *
     * @throws Exception
     */
    @Test
    public void springroot_info() throws Exception {
       expect().
              body("app.name", equalTo("springboot-jersey-swagger")).
              body("build.version", equalTo("1.0.0-SNAPSHOT")).
           when().
              get("/info");
    }
   
    /**
     * {"msg":"Hello Bright - application/json"}
     *
     * @throws Exception
     */
    @Test
    public void hello_get() {
       expect().
              body("msg", containsString("Hello Bright")).
        when().
              get("/api/v1/hello/Bright");
    }

}

6. Run It

6.1 Start It Up

By Maven command line in Windows, it would be:

1
2
3

> cd /d D:\development\workspaces\java\POC\springboot-jersey-swagger
> mvn package
> java -jar target/springboot-jersey-swagger-1.0.0-SNAPSHOT.jar

By Eclipse, simply open ApiApplication.java and click Run menu -> Run As -> Java Application, it would be booted up within seconds.

6.2 Take a Look at the API Documentation UI provided by Swagger

Simply open browser and key in: http://localhost:8000/

We can even try the services. Simply key in the parameter (name here) and click the “Try it out!” button, we can see everything in the same page including:

Curl command if we want to reproduce it on Curl

URL we just requested

Response Code

Response Body

Response Headers

7. Commit and Push to Git

Commit and push our first draft of Hello Service to our local Git Server.

By Git Bash:

$ git status
$ git add –A
$ git commit –m “first draft of Hello Service”
$ git push

Note: I also synced the code to GitHub, follow below steps:

Create a GitHub repository: itstarting/springboot-jersey-swagger

Execute commands like:

$ cd /D/development/workspaces/java/POC/springboot-jersey-swagger
$ git remote add github https://github.com/brightzheng100/springboot-jersey-swagger.git
$ git remote -v
github  https://github.com/brightzheng100/springboot-jersey-swagger.git (fetch)
github  https://github.com/brightzheng100/springboot-jersey-swagger.git (push)
origin  http://192.168.56.118:3000/bright/springboot-jersey-swagger.git (fetch)
origin  http://192.168.56.118:3000/bright/springboot-jersey-swagger.git (push) 
$ git push -u github master

By Eclipse it's very simple:

Right click project -> team -> Commit…

Choose all items in “Unstaged Changes”, right click -> Add to Index, which will add all items into “Staged Changes”

Key in comments in “Commit Message” and click “Commit and Push” button and eventually we have below result.

Well, the development works are done!

For complete source code, please visit my GitHub. Enjoy coding!

4 comments:

samala swathi7 August 2017 at 22:05
good information devops Online Training Hyderabad
soumya5 February 2018 at 00:59
Thank you for sharing wonderful information with us to get some idea about that content. check it once through Devops Online Training Hyderabad
Unknown6 July 2018 at 11:28
Hi there,
Getting the following error when trying to run the application:

***************************
APPLICATION FAILED TO START
***************************

Description:

Field cacheRepository in bright.zheng.poc.api.service.CacheService required a bean of type 'bright.zheng.poc.api.repository.CacheRepository' that could not be found.

Action:

Consider defining a bean of type 'bright.zheng.poc.api.repository.CacheRepository' in your configuration.

What is missing?
pranay18 September 2020 at 00:33
very special. easy to understand… spring boot certification course!

IT Rocks

Monday, 20 June 2016