Hello Boot - A simple Spring Boot Microservice

Install Spring Boot CLI

• Install Spring Boot CLI

• Unzip/Untar it and add spring-1.5.7.RELEASE/bin to your path

Create Simple Spring Boot project:

spring init --artifactId=helloboot --groupId=com.example --dependencies=web,actuator --extract

Import Project to IDE

Open your IDE and import the project

Add Simple Hello REST API

package com.example.helloboot;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Simple REST call that says from where its invoked from
 */
@RestController
public class HelloBootController {

    @GetMapping("/whereami")
    public String whereami() {
        return String.format("Hello from %s", System.getenv().getOrDefault("HOSTNAME", "localhost"));
    }
}

Build and run locally

./mvnw clean install spring-boot:run

Accessing application

The applicaiton can be accessed via browser like http://localhost:8080/whereami

(OR)

Simple curl curl http://localhost:8080/whereami ; echo ""

Deploying in Kubernetes

CRTL + C to stop the running application, if you have minishift running then do eval $(minishift docker-env) to setup required docker environment variables

./mvnw io.fabric8:fabric8-maven-plugin:3.5.30:setup (1)

./mvnw clean fabric8:deploy (2)

1. Setup fabric8 maven plugin

2. Build and Deploy the application to Kubernetes

Accessing application

curl http://helloboot-myproject.$(minishift ip).nip.io/whereami

You can view the URL from OpenShift console, and access the application via browser

Debugging Application

Add property to application.properties

message.prefix=Hello! (1)

1. a simple prefix to the messages, we can then use this property for debug

Update Hello REST API

package com.example.helloboot;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Simple REST call that says from where its invoked from
 */
@RestController
public class HelloBootController {

    @GetMapping("/whereami")
    public String whereami(@Value("${message.prefix}") String prefix) { (1)
        return String.format("% from %s", prefix, System.getenv().getOrDefault("HOSTNAME", "localhost"));
    }
}

1. Inject prefix property from application.properties

Add deployment.yaml

When we Deployed the application, the application will not be enabled for debug by default, to enable debug we need to add an env variable JAVA_DEBUG_ENABLE to the deployment.

Copy and paste the following content to a file called deployment.yaml in $PROJECT_HOME/src/main/fabric8

[[source,yaml]

spec:
  template:
    containers:
      spec:
        - env:
          - name: JAVA_ENABLE_DEBUG (1)
            value: true

1. Sets the Environment variable to enable debugging

Connecting and Debugging

ReDeploy the application with JAVA_ENABLE_DEBUG enabled, once the application is deployed successfully, run the following command

./mvw fabric8:debug (1)

1. This will do port-forward the debug port from your Kubernetes/OpenShift pod to localhost. The default port of the debugger is 5005. The default debug port can be overridden usign the Java system property fabric8.debug.port

(e.g.)

./mvw fabric8:debug -Dfabric8.debug.port=6005

Now you can connect to the Debugger with your favorite IDE

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