README.md

go-java-launcher

A simple Go program for launching Java programs from a fixed configuration. This program replaces Gradle-generated Bash launch scripts which are susceptible to attacks via injection of environment variables of the form JAVA_OPTS='$(rm -rf /)'.

The launcher accepts as configuration two YAML files as follows:

# StaticLauncherConfig
# The type of configuration, must be the string "java"
configType: java
# The version of the configuration format, must be the integer 1
configVersion: 1
# The main class to be run
mainClass: my.package.Main
# Path to the JRE, defaults to the JAVA_HOME environment variable if unset
javaHome: javaHome
# The classpath entries; the final classpath is the ':'-concatenated list in the given order
classpath:
  - ./foo.jar
# JVM options to be passed to the java command
jvmOpts:
  - '-Xmx1g'
# Arguments passed to the main method of the main class
args:
  - arg1

# CustomLauncherConfig
configType: java
configVersion: 1
# JVM options to be passed to the java command
jvmOpts:
  - '-Xmx2g'

The launcher is invoked as:

go-java-launcher [<path to StaticLauncherConfig> [<path to CustomLauncherConfig>]]

where the static configuration file defaults to ./launcher-static.yml and the custom configuration file defaults to ./launcher-custom.yml. It assembles the configuration options and executes the following command (where <static.xyz> and <custom.xyz> refer to the options from the two configuration files, respectively):

<javaHome>/bin/java \
  <static.jvmOpts> \
  <custom.jvmOpts> \
  -classpath <classpath entries> \
  <static.mainClass> \
  <static.args>

Note that the custom jvmOpts appear after the static jvmOpts and thus typically take precendence; the exact behaviour may depend on the Java distribution.

License

This repository is made available under the Apache 2.0 License.