Jlink image

While Scala does not officially offer support for the Java Platform Module System, and Cats Effect is itself built using JDK 8, Cats Effect applications can be run on JDKs derived using jlink (bundling only the classes required for the application to run).

Cats Effect applications only depend on JDK classes defined in the java.base module. Building a JDK derived using jlink always contains these classes, so projects that depend on cats-effect jars can be run out-of-the-box without additional configuration.

There is one exception to this. The java.base module does not bundle support for POSIX signals, which means that the a fiber dump functionality cannot be triggered by sending POSIX signals to the Cats Effect application process.

The POSIX signal functionality can be restored by adding a dependency on the jdk.unsupported module, which unlocks access to the sun.misc.Signal API.

sbt-native-packager

This sbt plugin can build jlink derived JDKs and can be configured to include the jdk.unsupported module as follows:

.settings(
  jlinkModules += "jdk.unsupported"
)