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Exercise_1_GettingStarted.md

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Exercise 1: Getting Started - Setup Tomcat Web Server

Learning Goal

Get familiar with the provided code base and understand how to test your microservice in your local environment. In this exercise you will start the microservice on your locally installed Tomcat web server while making use of Spring Dependency Injection.

Prerequisite - Import Project Into Eclipse (main branch)

  • Run VirtualBox and start your Virtual Machine (VM).
  • Run Eclipse inside the VM Important: If you are asked for a workspace, make sure to use the default workspace at /home/vagrant/workspace
  • Import the main branch of this Git Project as described below:

Initial Import

  • Select File - Import - Git - Projects from Git.

  • In the next dialog, select Clone URI and enter the URI https://github.com/SAP/cloud-bulletinboard-ads.git.

  • Important: Choose main as Initial branch

    • Use Next and Finish to go through the following dialogs (the default settings should be OK).

  • Modify the proxy setttings by updating the below mentioned fields in pom.xml with your own proxy details if your are behind any proxy.

    • Fields to be updated are: <http.proxyHost> and <http.proxyPort>.

  • Then update the Maven Settings: ALT+F5, OK

  • Make sure that you have checked out the main branch.

Step 1: Get to Know the Code

Take some time to familiarize yourself with the given bulletinboard-ads microservice. Concentrate on the src/main/java source folder and there in particular the following classes are now of interest: AppInitializer, the WebAppContextConfig and DefaultController.

Step 2: Run the Microservice in Eclipse

In order to run/debug the microservice within your Eclipse IDE you need to deploy the application on your Tomcat server instance.

  • Right-click the Tomcat server entry in the Servers View, select Add and Remove ..., and click Add to move your project to the configured ones.
  • Then (re)start the Tomcat server (see Eclipse documentation for your reference).
  • Ensure that in the console information similar to the one below is logged:
Okt 18, 2017 6:42:32 PM org.springframework.web.context.ContextLoader initWebApplicationContext
INFO: Root WebApplicationContext: initialization started
...
Okt 18, 2017 6:42:32 PM org.springframework.web.context.support.AnnotationConfigWebApplicationContext loadBeanDefinitions
INFO: Registering annotated classes: [class com.sap.bulletinboard.ads.config.WebAppContextConfig]
...
Okt 18, 2017 6:42:34 PM org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping register
INFO: Mapped "{[/],methods=[GET]}" onto public java.lang.String com.sap.bulletinboard.ads.controllers.DefaultController.get()
...
Okt 18, 2017 6:42:36 PM org.apache.catalina.core.ApplicationContext log
INFO: Initializing Spring FrameworkServlet 'DispatcherServlet'
...
Okt 18, 2017 6:42:36 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-nio-8080"]
Okt 18, 2017 6:42:36 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-nio-8009"]
Okt 18, 2017 6:42:36 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 6912 ms
  • Start the Web Browser and ensure that the following url http://localhost:8080/ returns OK
  • You can terminate the web server in the Eclipse Console view (red square button), or stop the Tomcat server explicitly in the Servers view.

[Optional] Step 3: Run the Microservice on the Command Line

Ensure that you are in the project root e.g. ~/git/cc-bulletinboard-ads-spring-webmvc.

Linux:

# prerequisite: navigate to the root directory of the project
$ source localEnvironmentSetup.sh
$ mvn tomcat7:run

Windows:

# prerequisite: navigate to the root directory of the project
$ localEnvironmentSetup.bat
$ mvn tomcat7:run

With the Tomcat Maven Plugin the maven build (including the tests) is triggered and if successful the application is run on an embedded tomcat.

  • Ensure that the following url http://localhost:8080/ shows OK
    • Note: If you got an exception Failed to initialize end point associated with ProtocolHandler ... then you most likely forgot to stop your server in Eclipse. There can always just be one tomcat running on a host:port (e.g. localhost:8080) address.
    • Note: If you need to use another port, you can change the default Tomcat port in the pom.xml at the setting maven.tomcat.port.
  • You can terminate the web server in the command window with CTRL+C.

[Optional] Step 4: Gain Application Insight With the Spring Boot Actuator

The main thing that the Spring Boot Actuator does is to add several helpful management endpoints to a Spring Web MVC-based application. Some of the endpoints are:

Method Endpoint Description
GET health Shows application health information (when the application is secure, a simple ‘status’ when accessed over an unauthenticated connection or full message details when authenticated).
GET beans Displays a complete list of all the Spring beans in your application.
GET mappings Displays a collated list of all @RequestMapping paths.
GET env Lists all environment and system property variables available to the application context
GET env/{name} Displays the value for a specific environment or property variable
GET metrics Lists metrics concerning the application

Note that the Actuator plugin is designed for Spring Boot applications, and therefore not all endpoints are accessible. Find a more detailed description here.

The next steps explains how to enable the Actuator.

Add Maven Dependency

Add the spring-boot-actuator dependency to your pom.xml using the XML view of Eclipse:

<!-- Actuator for adding management endpoints -->
<dependency>
	<groupId> org.springframework.boot</groupId>
	<artifactId>spring-boot-actuator</artifactId>
	<version>1.2.5.RELEASE</version>
	<exclusions>
		<exclusion>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
		</exclusion>
		<exclusion>
			<groupId>org.springframework</groupId>
			<artifactId>spring-context</artifactId>
		</exclusion>
	</exclusions>
</dependency>

Note: In this exercise we intentionally do NOT make use of the latest version of actuator for simplicity reasons. Please be aware of the possible security implications of using this productively as documented here.

Note: After you've changed the Maven settings, don't forget to update your Eclipse project (ALT-F5)!

Enable Auto-configuration

To enable the Spring Boot Actuator plugin you need to pretend to be a Spring Boot application by enabling auto-configuration.

Create a SpringBootActuatorConfig class in the com.sap.bulletinboard.ads.config package and provide the following annotations:

@Configuration
@EnableConfigurationProperties
@EnableAutoConfiguration(exclude = { DataSourceAutoConfiguration.class, RabbitAutoConfiguration.class })
public class SpringBootActuatorConfig {
}

With that Spring beans gets automatically configured depending on the @ConfigurationProperties annotated beans and what is found on the classpath.

Test

Start the Web Browser and ensure that the following url http://localhost:8080/health shows the status "UP". Note: The response type (media type) of this HTTP GET request is JSON. In order to analyze JSON responses best you can install a Chrome extension like JSON Viewer.

Remarks on using the Actuator in productive code

In the older versions of the Actuator (as used here), the endpoints are enabled for unauthenticated and unauthorized access.

That's why you should make sure that later, in your productive code you:

  • Use a version of spring-boot-actuator >= 1.5.4.RELEASE (and not 1.2.5.RELEASE as in this exercise).
  • Test your productive application that all the Spring Boot Actuator endpoints behave as expected (enabled / disabled or secured in the way you expect them to be).

Troubleshoot

  • Common issues are documented here.

Used Frameworks and Tools

© 2018 SAP SE
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