java.md

Getting started with wercker & Java

This guide is a step-by-step approach to developing, building and deploying a sample app with wercker within minutes.

While this guide uses PHP, the general concepts explained in this tutorial apply to every other programming language.

Requirements

To be able to follow along with this guide, you will need the following things:

Setting up the app

For this demo, we will be using Java Spring to create a simple web page that shows a counter which displays how many times the site has been visited. We will use Redis as a backend to save this data.

Before we can start developing, we have to fork and clone the sample app into our local development environment. After you've done that, cd into the project directory.

$ cd getting-started-java/

Developing the app

Now that we've setup our app we can start developing. Let's start by taking a closer look at the wercker.yml file included in your project folder.

wercker.yml

The wercker.yml is the only config file you need for using wercker. In it, you will define all your steps needed to successfully develop, build and deploy your application.

To get started however, we're only interested in developing our app, so let's take a closer look at this dev pipeline right now.

Dev pipeline

# The container definition we want to use for developing our app
box: combient/java-mvn

# Defining the development pipeline
dev:
  services:
    - id: redis
  steps:
    - script:
        code: export PORT='8082'
    - script:
        code: 'mvn package'
    - script:
        code: 'mvn spring-boot:run'

The first line specifies which container image you want to use for your project. Since we're developing with Java, we've already specified a Java image for you. These container images are retrieved from Docker Hub if no other registry is specified. You can read more about containers here.

In the dev clause we define what we want to happen in our development pipeline. First we describe which service we will be using alongside our main container, which in our case is Redis. We won't expand too much into how services work here, but you can read more on our devcenter.

In the steps section we describe which actions we want to take before we're ready Let's see these steps in action now and fire up our dev pipeline.

wercker dev

In your project folder, run wercker dev --publish 8080. You should end up with input similar to this:

(...)
mapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2016-02-22 15:50:33.508  INFO 111 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2016-02-22 15:50:33.643  INFO 111 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2016-02-22 15:50:33.657  INFO 111 --- [           main] resources.HelloResource                  : Started HelloResource in 8.721 seconds (JVM running for 16.642)
2016-02-22 15:55:20.314  INFO 111 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'
2016-02-22 15:55:20.314  INFO 111 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started
2016-02-22 15:55:20.336  INFO 111 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 22 ms
Connecting to redis at host 'redis'

Wercker first checks out your code and then sets up the container environment. This means that the container will be pulled from Docker Hub and subsequently started with access to your checked out code. It will then start executing all the steps that are defined in the wercker.yml.

Please note that the IP displayed here could be different for you, as this tutorial was written using docker-machine.

toonverbeek/java.md