openjdk-cnb

README

openjdk-cnb

The Cloud Foundry OpenJDK Buildpack is a Cloud Native Buildpack V3 that provides OpenJDK JREs and JDKs to applications.

This buildpack is designed to work in collaboration with other buildpacks which request contributions of JREs and JDKs.

Behavior

This buildpack will participate if any of the following conditions are met

• Another buildpack requires openjdk-jdk
• Another buildpack requires openjdk-jre

The buildpack will do the following if a JDK is requested:

• Contributes a JDK to a layer marked build and cache with all commands on $PATH
• Contributes $JAVA_HOME configured to the build layer
• Contributes $JDK_HOME configure to the build layer

The buildpack will do the following if a JRE is requested:

• Contributes a JRE to a layer with all commands on $PATH
• Contributes $JAVA_HOME configured to the layer
• Contributes -XX:ActiveProcessorCount to the layer
• Contributes $MALLOC_ARENA_MAX to the layer
• Disables JVM DNS caching if link-local DNS is available
• If metadata.build = true
  • Marks layer as build and cache
• If metadata.launch = true
  • Marks layer as launch
• Contributes jvmkill to a layer marked launch
• Contributes Memory Calculator to a layer marked launch

Configuration

Environment Variable	Description
$BP_JAVA_VERSION	Configure a specific JDK or JRE version. This value must exactly match a version available in the buildpack so typically it would configured to a wildcard such as 8.*.
$BPL_HEAD_ROOM	Configure the percentage of headroom the memory calculator will allocated. Defaults to 0.
$BPL_LOADED_CLASS_COUNT	Configure the number of classes that will be loaded at runtime. Defaults to 35% of the number of classes.
$BPL_THREAD_COUNT	Configure the number of user threads at runtime. Defaults to 250.

License

This buildpack is released under version 2.0 of the Apache License.