Vert.x 3 Application Deployment on Openshift using the DIY cartridge

This guide explains how a vert.x 3 application can be deployed on OpenShift using the DIY cartridge.

Be aware that the DIY Cartbridge does not support scalability. However if you just want to have you application running, it's very simple.

Step 1 - Create your application on OpenShift

First login or sign up on Openshift. Once done create a new application. If you don't have one already, you are invited to create one. You will have to upload a SSH Public Key to let you push to the Git repository hosting the application.

1. Choose a type of application When selecting the type of application, select Do-It-Yourself 0.1. You can search for diy in the search box.

2. Configure the application On the configure the application form, enter the requested data. You don't have to enter a git repository url, Openshift is going to create one for you.

Once done, click on the Create Application button (on the bottom of the page). It takes a couple of seconds, so don't worry.

3. Next steps

To use openshift ssh & git to push to openshift. need to install & setup rhc

Almost there. On this page, you can get the Git repository url. For example:

git clone ssh://[email protected]/~/git/diy2.git/
cd diy2/

Clone this repository on your system. It's where we are going to copy your application. If you have configured the public key to use, you may have to configure your ~/.ssh/config file to pick up the right key. Open the ~/ .ssh/config and add the following content (and don't forget to edit):

Host diy2-vertx3sample.rhcloud.com
    User 55656c6050044659b50000ce
    IdentityFile ~/.ssh/id_rsa_github  

Don't forget to edit the host, user and private key associated with the public key you have uploaded. The user and host can be found in the git url.

Note about deployment

OpenShift is listening for Git pushes. On every push it redeploys your application. In the context of this guide, we are going to push a Vert.x application packaged as a fat jar.

Step 2 - Application preparation

Deploying on OpenShift imposes a couple of conventions. Your server must be bound to OPENSHIFT_DIY_IP:OPENSHIFT_DIY_PORT.

Let's assume these environment variables are passed as two Java system variables respectively http.address and http .port. In that case your HTTP server should be initialized with:

@Override
public void start() throws Exception {
   vertx.createHttpServer().requestHandler(req -> { /* your code */ })
           // IMPORTANT : we need to use the port and address given by openshift.
           .listen(Integer.getInteger("http.port", 8080), System.getProperty("http.address"));
}

It's very important to use the OpenShift values. Your application is not allowed to bind any other socket.

Once you have updated your application, you need to package it as a fat jar. This is what will be deployed on OpenShift.

Step 3 - Preparing the environment and deployment

Clone the repository

You should have cloned the Git repository, and get such kind of content:

.
├── .openshift
│   ├── README.md
│   ├── action_hooks
│   │   ├── README.md
│   │   ├── start
│   │   └── stop
│   ├── cron
│   └── markers
├── README.md
├── diy
│   ├── index.html
│   └── testrubyserver.rb
└── misc
    └── .gitkeep

(for sake of simplicity, only relevant files are shown)

Let's do some cleanup. Delete the diy and misc directory, and create an application directory.

rm -Rf diy misc
mkdir application

Your application is going to be copied into the application directory.

Copy the scripts

There are three scripts to copy to .openshift/action_hooks:

• pre_start - provision Java 8: link
• start - Start the application: link
• stop - Stop the application: link

These scripts can be copied from this template.

Don't forget to put the execution permission on these scripts:

cd .openshift/action_hooks
chmod +x pre_start start stop

The pre_start script is required because Openshift does not provides a Java 8 JVM, so it installs one. The start script uses the installed JVM and launches the application. It redirects application output to logs/out.log and configure the http.port and http.address system properties. The stop script just stops the application.

Copy the application

The application's fat jar needs to be copied to the application directory.

Final review before deployment

So, you should get the following structure:

.
├── .openshift
│   ├── README.md
│   ├── action_hooks
│   │   ├── README.md
│   │   ├── pre_start
│   │   ├── start
│   │   └── stop
│   ├── cron
│   └── markers
├── README.md
└── application
    └── vertx-sample-3.0.0-SNAPSHOT-fat.jar  <= your fat jar

Deployment

It's deployment time. Deploying on Openshift is just a git push.

git add -A
git commit -m "initial version of my application"
git push

The first push take some time as the Java 8 JVM is installed. Don't worry, the script does this only once.

Here you are, you application should have started. If you go back to OpenShift and navigate to your application page, it gives you the root url. this url should be served by your application.

A note about Java 8

Vert.x applications require Java 8. Openshift(.com) provides Java 8 in /etc/alternatives/java_sdk_1.8.0. If you install OpenShift on your own server, you don't have to provide Java 8. The pre_start checks whether or not Java 8 is provided in the regular directory (the one listed above). If not it downloads and installs Java 8 alongside the application. However, this consumes lots of disk space. To avoid this just installs Java 8 in /etc/alternatives/java_sdk_8.