Microservices with Docker and Spring Boot

This guide is for someone interesting in quickly building a micro-service using the Spring Boot framework. Works great if you have prior JAX-RS / Jersey experience

Step-by-step guide

Add the steps involved:

1. Create a Maven Project
   1. Final Structure
      
   2. Pom ( Attached here )
      
2. Include Spring Boot Dependencies in your pom
   1. Parent Project
      

      <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.3.1.RELEASE</version> </parent>

   2. Dependencies
      

      <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jersey</artifactId> </dependency> </dependencies>

3. Create the Java main class – this is entry point with the @SpringBootApplication annotation
   1. App.java
      

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

4. Create the API Controller class
   1. Add Spring MVC methods for REST in the API controller class
      1. SimpleAPIController.java with SpringMVC only
         

         @Component @RestController @Path("/api") public class SimpleAPIController { @RequestMapping(value = "/springmvc", produces = "application/json") public Map<String, Object> springMvc() { Map<String, Object> data = new HashMap<String, Object>(); data.put("message", "Spring MVC Implementation of API is available"); return data; } }

   2. (Alternate/Additional) Add Jersery methods for REST in the API controller class
      1. SimpleAPIController.java with Jersey (Note: You need the spring boot jersey dependency in your pom)
         

         @Component @RestController @Path("/api") public class SimpleAPIController { @GET @Produces({ "application/json" }) public Response getMessage() { Map<String, Object> data = new HashMap<String, Object>(); data.put("message", "Jersey Implementation of API is available"); Response response = Response.ok().entity(data).build(); return response; } }

   3. (Alternate/Additional) Create a JerseyConfig class
      1. JerseryConfig.java – required for jersey rest implementation
         

         @Configuration public class JerseyConfig extends ResourceConfig { public JerseyConfig() { register(SimpleAPIController.class); } }

5. Build the Maven project
   1. Add the Spring boot maven build plugin
      

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

6. Execute the spring boot application
   1. Run in Eclipse as Java Application
      
   2. Run as a standalone Java Jar
      

      java -jar target/SimpleService-0.0.1-SNAPSHOT.jar

   3. Specify a different port and run as a standalone Java Jar

      java -Dserver.port=8090 -jar target/SimpleService-0.0.1-SNAPSHOT.jar

   4. Running in a docker container

      1. See: https://spring.io/guides/gs/spring-boot-docker/
      2. Docker file
         

         FROM java:8 VOLUME /tmp ADD SimpleService-0.0.1-SNAPSHOT.jar app.jar RUN bash -c 'touch /app.jar' ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]