Setting up development environment with Docker, Maven and IntelliJ

This post walks through the setup of development environment for Docker with IntelliJ using Maven. We will use a Spring boot application and configure IntelliJ for iterative development.

Spring Boot Application

The demo application is a simple one page app which displays a chart of VIX index. We will wire Quandl’s web service to fetch the historical data about VIX index and use CanvasJS charting library to display the chart. You can learn more about Spring Boot application with this Spring Guide. Here are some highlights:

Application.java
@SpringBootApplication is the convenience annotation that marks the class as an entry point.

	@SpringBootApplication
	public class Application extends SpringBootServletInitializer
	{
	public static void main(String[] args)
	{
	SpringApplication.run(Application.class, args);
	}
	}

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AppConfig.java
Setup Spring wiring using java in this class. It is any class that is marked with @Configuration annotation.

	@Configuration
	@ComponentScan(basePackageClasses = Application.class)
	public class AppConfig
	{
	@Bean
	public RestTemplate restTemplate() {
	RestTemplate restTemplate = new RestTemplate(httpRequestFactory());
	List<HttpMessageConverter<?>> converters = restTemplate.getMessageConverters();
	for (HttpMessageConverter<?> converter : converters) {
	if (converter instanceof MappingJackson2HttpMessageConverter) {
	MappingJackson2HttpMessageConverter jsonConverter = (MappingJackson2HttpMessageConverter) converter;
	jsonConverter.setObjectMapper(new ObjectMapper());
	jsonConverter.setSupportedMediaTypes(Arrays.asList(new MediaType("application", "json", MappingJackson2HttpMessageConverter.DEFAULT_CHARSET), new MediaType("text", "javascript", MappingJackson2HttpMessageConverter.DEFAULT_CHARSET)));
	}
	}
	return restTemplate;
	}
	@Bean
	public ClientHttpRequestFactory httpRequestFactory() {
	return new HttpComponentsClientHttpRequestFactory(httpClient());
	}
	@Bean
	public HttpClient httpClient() {
	PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager();
	CloseableHttpClient closeableHttpClient = HttpClientBuilder.create().setConnectionManager(connectionManager).build();
	connectionManager.setMaxTotal(5);
	connectionManager.setDefaultMaxPerRoute(5);
	return closeableHttpClient;
	}
	}

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View - JSPs
Application’s view pages are under /webapp/WEB-INF/jsp.  application.properties file provided configuration to wire Spring’s view resolver.

Static Content
Application’s static content under src/main/resources/static as below.

You can find entire source code here on github. 

pom.xml
spring-boot-maven-plugin make executing lifecycle events easier. If you open IntelliJ’s Maven window, you will see all spring-boot-run, which will allow you to run the project. You can also create run configuration for easy access.

Setting up Docker

You can setup Docker environment by following instructions from docker for mac documentation.

Docker, Maven and IntelliJ

We will use docker-maven-plugin from com.spotify

Docker file

Create src/main/docker/Dockerfile. 

	FROM frolvlad/alpine-oraclejdk8:slim
	VOLUME /tmp
	ADD options-analyzer-1.0-SNAPSHOT.jar app.jar
	RUN sh -c 'touch /app.jar'
	ENTRYPOINT ["java", "-Djava.security.egd=file:/dev/./urandom", "-jar", "/app.jar"]

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pom.xml

Configuration for docker plugin

	<plugin>
	<groupId>com.spotify</groupId>
	<artifactId>docker-maven-plugin</artifactId>
	<version>0.4.10</version>
	<configuration>
	<serverId>docker-hub</serverId>
	<imageName>${docker.image.prefix}/${project.artifactId}</imageName>
	<dockerDirectory>src/main/docker</dockerDirectory>
	<resources>
	<resource>
	<targetPath>/</targetPath>
	<directory>${project.build.directory}</directory>
	<include>${project.build.finalName}.jar</include>
	</resource>
	</resources>
	</configuration>
	</plugin>

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ServerId tag specifies the docker repository you want to push to. The credentials to the serverId needs to be provided in your maven settings.xml. You have option of mvn encrypting the password. Follow instructions here

	<servers>
	<server>
	<id>docker-hub</id>
	<username>your_user_name</username>
	<password>your_password</password>
	<configuration>
	<email>your_email</email>
	</configuration>
	</server>

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Run Configuration

To get it running in IntelliJ, you can setup Run Configuration as follows: 

1. Open Run -> Edit Configuration

2. Add Maven Configuration

3. Provide maven command line as clean package docker:build

4. Go to the Runner tab and provide environment variables

     5. Similarly, you can also create docker:push run configuration, if you want to push docker image to docker registry.