Thorntail development mode: no more redeploys

As a Java developer you know the pain which is having to redeploy the entire application when you want to test the code change you made.

You know that there are IDE plugins that can help in this task, but these IDE plugins may only work in certain conditions, like deploying a WAR in an application server. In 2018 this may not be the case, you may not be working with an application server, you may be doing a fat JAR with all your stuff in there.Or you may not be even using an IDE.

We already talked about Wildfly Swarm here and it was recently renamed to Thorntail and it comes with an out of the box plugin that allows you to set a DEV MODE. In DEV MODE your Java server side code can magically be reloaded without any action on your side, you just have to compile the code, it  watches the class changes and reload the server! Yes, guys, this is Java and no redeploy it needed anymore.

Thorntail hello world

This is Thorntail

To show this feature let's start from the beginning: a Thorntail hello world. There's no Thorntail release, but we can use the snapshot version and there's a hello world example available in Thorntail github, but I used a maven archetype. The following command (considering you have maven and java installed) will generate a simple JAX-RS  (make sure you have added the following repository to your settings.xml:  https://oss.sonatype.org/content/repositories/snapshots)

mvn archetype:generate \

    -DarchetypeGroupId=io.thorntail.archetypes \

    -DarchetypeArtifactId=thorntail-jaxrs-archetype \

    -DarchetypeVersion=1.0-SNAPSHOT \

    -DgroupId=org.fxapps \

    -DartifactId=hello-thorntail \

    -Dversion=1.0-SNAPSHOT

Once you generate your project notice it will come with a built in test. Thorntail has a test framework as well, isn't that awesome?

Run mvn clean package then you can run your service in a few different ways depending on the mode you choose in the thorntail maven plugin (see the documentation for more information). By default it looks to use the mode thin, so to run your app you need to run the script $PROJECT_HOME/target/$FINAL_NAME-bin/bin/run.sh 

Our Hello World is done. Now I want to add a new method to my JAX-RS resource MyResource, don't want to build the project every time I modify MyResource.java, so let's try the thorntail dev tools. 

Using Thorntail dev tools

The first action is to add the thorntail-devtools dependency to the project's pom.xml:

Then make sure that you are using thing mode in thorntail plugin, see:

According to the documentation it will be only active if we set the system variable THORNTAIL_DEV_MODE. So let's set it to reload:

THORNTAIL_DEV_MODE=reload

Having that done, package the project one time by running mvn package, then run the same script mentioned previously: $PROJECT_HOME/target/$FINAL_NAME-bin/bin/run.sh 

In the screencast below it you can see how it works (restart mode).

With a simple tool I can observe changes in the src/main directory and run mvn compile.
In the video you will see only the restart mode, I will update this post with reload mode soon.

That's all, folks the application code can be found on my github!