Java Buildpack

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Use the Java buildpack with applications written in Grails, Play, Spring, or any other JVM-based language or framework.

See the following topics:

See the Java Buildpack Release Notes for information about specific versions. You can find the source for the Java buildpack on GitHub:

Buildpack and Application Logging

The buildpack only runs during the staging process, and therefore only logs staging information such as the downloaded components, configuration data, and work performed on your application by the buildpack.

The Java buildpack source documentation states the following:

  • The Java buildpack logs all messages, regardless of severity, to APP-DIRECTORY/.java-buildpack.log. The buildpack also logs messages to $stderr, filtered by a configured severity level.

  • If the buildpack fails with an exception, the exception message is logged with a log level of ERROR. The exception stack trace is logged with a log level of DEBUG. This prevents users from seeing stack traces by default.

Once staging completes, the buildpack stops logging. The Loggregator handles application logging.

Your application must write to STDOUT or STDERR for its logs to be included in the Loggregator stream. For more information, see the Application Logging in Cloud Foundry topic.

BOSH Custom Trusted Certificate Support

Java Buildpack versions 3.7 and later support BOSH configured custom trusted certificates.

Run the following command to configure support for this feature:


Memory Constraints in Java Buildpack 4.0

The new memory calculator in Java Buildpack 4.0 accounts for the following memory regions:

  • -Xmx: Heap
  • -XX:MaxMetaspaceSize: Metaspace
  • -Xss: Thread Stacks
  • -XX:MaxDirectMemorySize: Direct Memory
  • -XX:ReservedCodeCacheSize: Code Cache
  • -XX:CompressedClassSpaceSize: Compressed Class Space

Applications which previously ran in 512 MB or smaller containers may no longer be able to. Most applications will run if they use the Cloud Foundry default container size of 1G without any modifications. However, you can configure those memory regions directly as needed.

The Java buildpack optimizes forĀ all non-heap memory regionsĀ first and leaves the remainder for the heap.

The Java buildpack builds a print a histogram of the heap to the logs when the JVM encounters a terminal failure.

The Cloud Foundry default Java buildpack is currently 3.x, in order to allow time for applications to upgrade to 4.x.

For more information, see Java Buildpack 4.0.

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