Debug a docker driven tomcat java web application

This repository is built as shown on

https://blog.docker.com/2016/09/java-development-using-docker/

Installation steps (on mac, with docker toolbox)

Install Java

Install the Java SE Development Kit to your local machine in order to build source code.

http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

An alternative could be to use a docker container for compiling:

https://hub.docker.com/_/openjdk/

Download IntelliJ IDEA

https://www.jetbrains.com/idea/download/#section=mac

Install Docker/Docker-Compose

Install either docker toolbox or docker for mac.

https://docs.docker.com/compose/install/

For better access on mounted filesystem install docker-machine-nfs:

https://github.com/adlogix/docker-machine-nfs

Create a host entry

sudo nano /etc/hosts

Add another entry like (docker toolbox)

192.168.99.100  dev.project.io

or

127.0.0.1  dev.project.io

Clone this project

cd /your/projects/folder

git clone git@github.com:shockwavemk/tomcat-debug-template-app.git

Startup of project

Start up intelliJ IDEA and open your cloned folder:

Docker

Open the terminal,

and start docker containers with:

docker-compose build
docker-compose up -d

If not yet started, docker will notice to startup docker machine:

docker-machine start
eval "$(docker-machine env default)"

The following ports are used in this project:

• 80 for tomcat webserver
• 8000 for debug
• 3306 for mysql

Build the project

Build the project (Build > Build Project)

Configure remote debugging

Go to Run > Debug,

and configure a new "remote" entry:

Most needed configurations are already inserted by IntelliJ IDEA, but two values have to be changed:

• Change host to: dev.project.io
• Change port to: 8000

Database edit in IntelliJ IDEA

Open the database window:

Add a new entry,

download the missing driver for mysql,

and configure the mysql docker container bound to localhost / docker-machine:

Current docker-container config reveals the username/password:

Debug the project

Start the debugging session with a click onto the green bug:

A new tool window should appear with a "connected" message:

Open your web-browser to open the web-application:

http://dev.project.io/manager/html

The docker-application is hosted behind the a sub-path called /UserSignup. A click onto the link will lead you to the start window of the demo-application:

In the code editor window open the controller class "UserController". Mark the line 27 with a breakpoint:

Navigate to the address

http://dev.project.io/UserSignup/signup.html

in your web-browser:

The application execution should stop at breakpoint, IntelliJ IDEA should show breakpoint details and active variables.

Hints

Template changes are not immediately done in web-site, even on execution of "build". All assets are saved in a file called UserSignup.war.

This file can be recompiled by Build > Build Artifacts ... > All artifacts