This is a sample Java / Maven / Spring Boot application that can be used as a starter for creating a microservice complete with built-in health check, metrics and much more. I hope it helps you.
This application is packaged as a war which has Tomcat 7 embedded. No Tomcat or JBoss installation is necessary. You run it using the java -jar command.
- Clone this repository
- Make sure you are using JDK 1.7 and Maven 3.x
- You can build the project and run the tests by running
mvn clean package - Once successfully built, you can run the service by one of these two methods:
java -jar -Dspring.profiles.active=test target/spring-boot-rest-example-0.2.0.war
or
mvn spring-boot:run -Drun.arguments="spring.profiles.active=test"
- Check the stdout to make sure no exceptions are thrown
Once the application runs you should see something like this
2014-10-04 18:24:58.870 INFO 10190 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8090/http
2014-10-04 18:24:58.872 INFO 10190 --- [ main] com.khoubyari.example.Application : Started Application in 6.764 seconds (JVM running for 7.06)
The service is just a simple hotel review REST service. It uses an in-memory database to store the data. You can also do with a relational database like MySQL or PostgreSQL. If your database connection properties work, you can call some REST endpoints defined in com.khoubyari.example.api.rest.hotelController on port 8090. (see below)
More interestingly, you can start calling some of the operational endpoints (see full list below) like /metrics and /health (these are available on port 8091)
You can use this sample service to understand the conventions and configurations that allow you to create a DB-backed RESTful service. Once you understand and get comfortable with the sample app you can add your own services following the same patterns as the sample service.
Here is what this little application demonstrates:
- Full integration with the latest Spring Framework: inversion of control, dependency injection, etc.
- Packaging as a single war with embedded container (tomcat 7): No need to install a container separately on the host just run using the
java -jarcommand - Demonstrates how to set up healthcheck, metrics, info, environment, etc. endpoints automatically on a configured port. Inject your own health / metrics info with a few lines of code.
- Writing a RESTful service using annotation: supports both XML and JSON request / response; simply use desired
Acceptheader in your request - Exception mapping from application exceptions to the right HTTP response with exception details in the body
- Spring Data Integration with JPA/Hibernate with just a few lines of configuration and familiar annotations.
- Automatic CRUD functionality against the data source using Spring Repository pattern
- Demonstrates MockMVC test framework with associated libraries
- All APIs are "self-documented" by Swagger using annotations
Here are some endpoints you can call:
http://localhost:8091/env
http://localhost:8091/health
http://localhost:8091/info
http://localhost:8091/metrics
POST /example/v1/hotels
Accept: application/json
Content-Type: application/json
{
"name" : "Beds R Us",
"description" : "Very basic, small rooms but clean",
"city" : "Santa Ana",
"rating" : 2
}
RESPONSE: HTTP 201 (Created)
Location header: http://localhost:8090/example/v1/hotels/1
http://localhost:8090/example/v1/hotels?page=0&size=10
Response: HTTP 200
Content: paginated list
PUT /example/v1/hotels/1
Accept: application/json
Content-Type: application/json
{
"name" : "Beds R Us",
"description" : "Very basic, small rooms but clean",
"city" : "Santa Ana",
"rating" : 3
}
RESPONSE: HTTP 204 (No Content)
Spring Boot is an "opinionated" application bootstrapping framework that makes it easy to create new RESTful services (among other types of applications). It provides many of the usual Spring facilities that can be configured easily usually without any XML. In addition to easy set up of Spring Controllers, Spring Data, etc. Spring Boot comes with the Actuator module that gives the application the following endpoints helpful in monitoring and operating the service:
/metrics Shows “metrics” information for the current application.
/health Shows application health information.
/info Displays arbitrary application info.
/configprops Displays a collated list of all @ConfigurationProperties.
/mappings Displays a collated list of all @RequestMapping paths.
/beans Displays a complete list of all the Spring Beans in your application.
/env Exposes properties from Spring’s ConfigurableEnvironment.
/trace Displays trace information (by default the last few HTTP requests).
This project uses an in-memory database so that you don't have to install a database in order to run it. However, converting it to run with another relational database such as MySQL or PostgreSQL is very easy. Since the project uses Spring Data and the Repository pattern, it's even fairly easy to back the same service with MongoDB.
Here is what you would do to back the services with MySQL, for example:
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
---
spring:
profiles: mysql
datasource:
driverClassName: com.mysql.jdbc.Driver
url: jdbc:mysql://<your_mysql_host_or_ip>/bootexample
username: <your_mysql_username>
password: <your_mysql_password>
jpa:
hibernate:
dialect: org.hibernate.dialect.MySQLInnoDBDialect
ddl-auto: update # todo: in non-dev environments, comment this out:
hotel.service:
name: 'test profile:'
java -jar -Dspring.profiles.active=mysql target/spring-boot-rest-example-0.2.0.war
or
mvn spring-boot:run -Drun.arguments="spring.profiles.active=mysql"
Run the service with these command line options:
mvn spring-boot:run -Drun.jvmArguments="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005"
and then you can connect to it remotely using your IDE. For example, from IntelliJ You have to add remote debug configuration: Edit configuration -> Remote.