run-java.sh is a universal startup script for Java applications. It can be influenced by setting the environment variables described below.

run-java.sh can be used directly or it can be easily included in various build systems:

Maven builds can declare a dependency on

<dependency>
  <groupId>io.fabric8</groupId>
  <artifactId>run-java-sh</artifactId>
  <version>0.0.1-SNAPSHOT</version>
</dependency>

Then, within your code the script can be obtained with

// Script as string
String script = RunShLoader.getRunScript();

// Copy it to a destination, possibly somwhere below target/
RunShLoader.copyRunScript(new File("target/assembly/run-java.sh"));

You can also use the run script directly from this build:

mvn exec:java | sh

fish-pepper is a Docker build composition tool based on templates. It has a concept called blocks which is a collection of templates and files to be copied into a Docker image. Blocks can also be obtained remotely from a Git repository. In order to use this startup script for fish-pepper, you need to add the following refernce to the main configuration fish-pepper.yml in you Docker image build:

blocks:
  - type: "git"
    url: "https://github.com/fabric8io/run-java-sh.git"
    path: "fish-pepper"

From within the Docker templates you then can reference this block as usual e.g. {{= fp.block('run-java-sh','copy.dck') }} for adding the proper COPY commands to your Dockerfile and copying over the run script into you Docker build directory.

For more information on fish-pepper please refer to its documentation.

The most important environment variables are

• JAVA_APP_DIR directory holding jar file.
• JAVA_MAIN_CLASS A main class to use as argument for java. When this environment variable is given. If a file $JAVA_APP_DIR/classpath is given this will be used, otherwise all jar files in $JAVA_APP_DIR are added to the classpath in alphabetical order. The directory $JAVA_APP_DIR itself is added to the classpath, too.
• JAVA_APP_JAR A jar file with an appropriate manifest so that it can be started with java -jar if no $JAVA_MAIN_CLASS is set. In all cases this jar file is added to the classpath, too.
• JAVA_OPTIONS options to add when calling java

If the main class modus is used, the script tries to lookup a classpath from the file classpath. This could e.g. be created by a Maven plugin to keep the proper maven dependency order.

If a script run-java-options is on your path, it is called to obtain startup parameters for an agent like agent bond, a multipurpose agent currently including Jolokia and jmx_exporter, a Prometheus metrics exporting agent. More information can be found in the documentation to agent bond, which also provided a fish-pepper block.

Remote debugging over port 5005 can be switched on by setting the environment variable JAVA_ENABLE_DEBUG.

These and other supported environment variables are described in detail in a separate document.