Setup

This guide will walk you through setting up JRECC for your local machine.

Create a configuration file

First, you need to create a configuration file. The location of the configuration file depends on your operating system:

• Windows: C:\Users\<user>\AppData\Roaming\jrecc\jrecc.yml, or %APPDATA%\jrecc\jrecc.yml
• MacOS: /Users/<user>/Library/Application Support/jrecc/jrecc.yml
• Linux: ~/.config/jrecc/jrecc.yml, or ${XDG_CONFIG_HOME}/jrecc/jrecc.yml

The configuration file needs to contain at a minimum, the following entries:

license: # Your license key purchased from jrecc.net
remoteExecution:
  url: # URL to your RE-API server
  instanceName: # RE-API instance name

Create a project

Create a project configuration file

Next, lets create a project to use JRECC. Choose a directory for your project, e.g. example-project, and create a new jrecc.yml file inside.

name: example-project

Executing the compiler

Next, let's run JRECC in this directory to verify that our configuration is loading correctly.

$ java -jar compiler-0.0.1.jar
Searching for project configuration in /home/user/.config/jrecc
Loading configuration from file /home/user/.config/jrecc/jrecc.yml
Searching for project configuration in /home/user/example-project
Loading configuration from file /home/user/example-project/jrecc.yml
License validated with ID <ID>
 usage:  compiler [-cp <path>] [-d <directory>] [-encoding <encoding>] [-g]
    [--proc <arg>] [-release <release>] [-s <directory>] [-source
    <release>] [-sourcepath <path>] [-target <release>] [-version]

We can see in the output that both our user and project configuration files are being loaded. Since we didn't provide any command line arguments to our compiler, just the usage was printed.

Compiling a simple Java program

Let's verify that we can successfully execute the compiler by building a simple Java program.

Create a new file, Main.java:

// Main.java
public class Main {
    public static void main(String[] args) {
        System.out.println("Hello World");
    }
}

Now lets compile this:

java -jar compiler-0.0.1.jar Main.java

The command will fail, with an error message depending on the remote execution environment that you are using. In this example, we are using BuildGrid, which fails with the following error:

bwrap: execvp javac: No such file or directory

The failure is due to the remote execution environment not being populated with the necessary files to successfully execute javac. When no files are specified, the remote execution sandbox environment is completely empty. We need to update our project configuration to include any files that we want to be available in the sandbox.

Adding files to the remote execution environment

Modify our project's jrecc.yml file to include the following configuration:

name: example-project
all:
  include:
    ubuntu:
      type: archive
      uri: https://cdimage.ubuntu.com/ubuntu-base/releases/noble/release/ubuntu-base-24.04.3-base-amd64.tar.gz
      sandboxPath: /
      baseDirectory: ''
      sha256: 6bc2cde3930ad088b3bb46fa45279e96d25bc3810f209850ecbe4722711874f9
    java:
      type: archive
      uri: https://download.java.net/java/GA/jdk24.0.2/fdc5d0102fe0414db21410ad5834341f/12/GPL/openjdk-24.0.2_linux-x64_bin.tar.gz
      sandboxPath: /usr/lib/jvm/
      baseDirectory: ''
      sha256: 635050717feab0e4c283c8e90e79e944a2b65a3b6b21f1d37dcaadad4cc29548
  environment:
    PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/bin:/usr/lib/jvm/jdk-24.0.2/bin

This configuration adds several files to our sandbox environment.

The first is Ubuntu 24.04.3, which will be the base operating system that will host our project.

Next, is OpenJDK 24.0.2, which will be the Java compiler that we will execute in the sandbox.

Finally, the PATH environment variable is set to include the default paths provided by Ubuntu, as well as OpenJDK 24.

Let's verify that we have our compiler set up by running javac -version in our sandbox.

java -jar compiler-0.0.1.jar -version

Output:

javac 24.0.2

Now let's try and build our simple Java program again.

```shell
java -jar compiler-0.0.1.jar Main.java
java Main.class

Output:

Hello World

We have successfully compiled a simple Java program using remote execution.