java_hello_world

Java sample

This sample demonstrates how a java application can be run in Mystikos

It is recommended that you understand how to use EXT2 file system and how applications can be packaged Mystkos before proceeding with this sample. Please refer to the README for the helloworld sample to obtain the necessary information.

Transform a Dockerfile into a root file system

Dockerfile imports from openjdk:13-alpine. The javac command is used to compile helloworld.java into class files that run on a JVM. myst-appbuilder is used to convert the Dockerfile into a directory containing all the files needed to run this application in Mystikos.

myst-appbuilder -v -d Dockerfile

After this, the appdir generated can be converted into a cpio archive using myst mkcpio or an EXT2 file system using myst mkext2that can be loaded into Mystikos. In this sample, we use an EXT2 file system.

Functionality

This sample prints hello world from a java application. The source code is contained in helloworld.java.

Running the sample

To run the sample in package mode, use make run.

To run the sample using myst exec-sgx, use make runexec.

Configuration Parameters

The configuration used in this sample is very similar to that in the C helloworld sample. Please refer to the helloworld sample for more details. It does use more memory than the helloworld sample(which is written in C). This is in order to run the JVM. After mounting the root file system, Mystikos invokes /opt/openjdk-13/bin/java with ApplicationParameters specifying helloworld.

{
    "Debug": 1,
    "ProductID": 1,
    "SecurityVersion": 1,
    "UserMemSize": "4096m",
    "CurrentWorkingDirectory": "/app",
    "ApplicationPath": "/opt/openjdk-13/bin/java",
    "ApplicationParameters": ["helloworld"]
}

To learn more about configuration, please refer to related documentation.