This is a Heroku buildpack for Java apps. It uses Maven 3.2.5 to build your application and OpenJDK 8u20 to run it (by default).
This fork also installs node.js and npm and uses webapp-runner to run the .war without requiring a bundled tomcat in Dokku.
Two webapp-runner versions are supported:
- Vincit's fork that uses Tomcat 7.0.
- heroku's official version that currently uses Tomcat 8.5. Note! Heroku's version does not support
--force-httpsoption.
By default, Vincit's version of webapp-runner is being used, and the Heroku's version can be selected by defining environment variable WEBAPP_RUNNER_VERSION=heroku.
E.g.
$ ssh [email protected] config:set <app name> WEBAPP_RUNNER_VERSION=heroku
# Set explicitly Vincit's version of webapp-runner to be used
$ ssh [email protected] config:set <app name> WEBAPP_RUNNER_VERSION=Vincit
The buildpack will detect your app as Java if it has a pom.xml file in its root directory. It will use Maven to execute the build defined by your pom.xml and download your dependencies. The .m2 folder (local maven repository) will be cached between builds for faster dependency resolution. However neither the mvn executable or the .m2 folder will be available in your slug at runtime.
For more information about using Java and buildpacks on Heroku, see these Dev Center articles:
- Heroku Java Support
- Introduction to Heroku for Java Developers
- Deploying Tomcat-based Java Web Applications with Webapp Runner
- Deploy a Java Web Application that launches with Jetty Runner
- Using a Custom Maven Settings File
- Using Grunt with Java and Maven to Automate JavaScript Tasks
Create a system.properties file in the root of your project directory and set java.runtime.version=1.7.
Example:
$ ls
Procfile pom.xml src
$ echo "java.runtime.version=1.7" > system.properties
$ git add system.properties && git commit -m "Java 7"
$ git push heroku master
...
-----> Heroku receiving push
-----> Fetching custom language pack... done
-----> Java app detected
-----> Installing OpenJDK 1.7... done
...
The system.properties file also allows for maven.version entry
(regardless of whether you specify a java.runtime.version entry). For example:
java.runtime.version=1.7
maven.version=3.1.1
Supported versions of Maven include 3.0.5, 3.1.1 and 3.2.5. You can request new
versions of Maven by submitting a pull request against vendor/maven/sources.txt.
There are three config variables that can be used to customize the Maven execution:
MAVEN_CUSTOM_GOALS: set toclean installby defaultMAVEN_CUSTOM_OPTS: set to-DskipTests=trueby default
These variables can be set like this:
$ heroku config:set MAVEN_CUSTOM_GOALS="clean package"
$ heroku config:set MAVEN_CUSTOM_OPTS="--update-snapshots -DskipTests=true"Other options are available for defining custom a settings.xml file.
To make changes to this buildpack, fork it on Github. Push up changes to your fork, then create a new Heroku app to test it, or configure an existing app to use your buildpack:
# Create a new Heroku app that uses your buildpack
heroku create --buildpack <your-github-url>
# Configure an existing Heroku app to use your buildpack
heroku config:set BUILDPACK_URL=<your-github-url>
# You can also use a git branch!
heroku config:set BUILDPACK_URL=<your-github-url>#your-branch
For example if you want to have maven available to use at runtime in your application, you can copy it from the cache directory to the build directory by adding the following lines to the compile script:
for DIR in ".m2" ".maven" ; do
cp -r $CACHE_DIR/$DIR $BUILD_DIR/$DIR
done
This will copy the local maven repo and maven binaries into your slug.
Commit and push the changes to your buildpack to your Github fork, then push your sample app to Heroku to test. Once the push succeeds you should be able to run:
$ heroku run bash
and then:
$ ls -al
and you'll see the .m2 and .maven directories are now present in your slug.
Licensed under the MIT License. See LICENSE file.