Java SDK

RBS provides comprehensive Java support with automatic JDK management, Maven-compatible dependency resolution, JUnit 5 auto-inclusion, Spring Boot support, linting, and container image building.

Setup

Toolchain

load("@rbs//java/toolchain.rbs", "java_toolchain", "java_test_deps")

# Auto-downloads JDK 17
java_toolchain(name = "java", version = "17.0.11")

# Auto-installs JUnit 5 for tests
java_test_deps()

Dependencies

Define external Java packages using java_repository. Supports Maven coordinates.

load("@rbs//java/dependencies.rbs", "java_repository")

java_repository(
    name = "spring_boot_web",
    package = "org.springframework.boot:spring-boot-starter-web",
    version = "3.2.2",
)

Rules

`java_library`

Creates a reusable Java library (JAR).

load("@rbs//java/rules.rbs", "java_library")

java_library(
    name = "springboot_lib",
    srcs = [
        "src/main/java/com/example/springboot/Application.java",
        "src/main/java/com/example/springboot/GreetingService.java",
        "src/main/java/com/example/springboot/Calculator.java",
    ],
    deps = [
        "@external://org_springframework_boot_spring_boot_starter_web:3.2.2",
    ],
)

Attribute	Type	Description
`name`	string	Unique target name (required).
`srcs`	list	Java source files.
`deps`	list	Dependencies (local or `@external://`).
`resources`	list	Resource files to include in the JAR.

`java_binary`

Creates an executable Java application.

load("@rbs//java/rules.rbs", "java_binary")

java_binary(
    name = "app",
    srcs = glob(["src/main/java/**/*.java"]),
    main = "com.example.springboot.Application",
    resources = ["src/main/resources/application.properties"],
    deps = [
        "@external://org_springframework_boot_spring_boot_starter_web:3.2.2",
    ],
    javaopts = ["-Djava.awt.headless=true", "-Xmx512m"],
)

Attribute	Type	Description
`name`	string	Unique target name (required).
`srcs`	list	Java source files.
`main`	string	Fully qualified main class (required).
`deps`	list	Dependencies.
`resources`	list	Resource files (e.g., `application.properties`).
`javaopts`	list	JVM options.

`java_test`

Runs Java tests. JUnit 5 is automatically included — no manual dependency required.

load("@rbs//java/rules.rbs", "java_test")

# Unit test — just depend on the code being tested
java_test(
    name = "greeting_service_test",
    srcs = [
        "src/main/java/com/example/springboot/GreetingService.java",
        "src/test/java/com/example/springboot/GreetingServiceTest.java",
    ],
    deps = [
        "@external://org_springframework_boot_spring_boot_starter_web:3.2.2",
    ],
    args = ["--select-class=com.example.springboot.GreetingServiceTest"],
)

# Full test suite
java_test(
    name = "all_tests",
    srcs = glob(["src/main/java/**/*.java", "src/test/java/**/*.java"]),
    deps = [
        "@external://org_springframework_boot_spring_boot_starter_web:3.2.2",
    ],
    args = [
        "--select-package=com.example.springboot",
        "--include-classname=.*Test",
    ],
)

Attribute	Type	Description
`name`	string	Unique target name (required).
`srcs`	list	Test and source files.
`deps`	list	Dependencies.
`args`	list	JUnit 5 console launcher arguments.

`java_lint`

Runs static analysis on Java source files.

load("@rbs//java/rules.rbs", "java_lint")

java_lint(
    name = "app_lint",
    srcs = glob(["src/main/java/**/*.java"]),
)

Example: Spring Boot Application

WORKSPACE.rbs
BUILD.rbs
Commands

load("@rbs//java/toolchain.rbs", "java_toolchain", "java_test_deps")
load("@rbs//java/dependencies.rbs", "java_repository")

java_toolchain(name = "java", version = "17.0.11")
java_test_deps()

java_repository(
    name = "spring_boot_web",
    package = "org.springframework.boot:spring-boot-starter-web",
    version = "3.2.2",
)

load("@rbs//java/rules.rbs", "java_binary", "java_library", "java_test", "java_lint")
load("@rbs//oci/rules.rbs", "oci_image")

java_library(
    name = "springboot_lib",
    srcs = glob(["src/main/java/**/*.java"]),
    deps = ["@external://org_springframework_boot_spring_boot_starter_web:3.2.2"],
)

java_binary(
    name = "app",
    srcs = glob(["src/main/java/**/*.java"]),
    main = "com.example.springboot.Application",
    resources = ["src/main/resources/application.properties"],
    deps = ["@external://org_springframework_boot_spring_boot_starter_web:3.2.2"],
    javaopts = ["-Djava.awt.headless=true"],
)

java_test(
    name = "greeting_service_test",
    srcs = [
        "src/main/java/com/example/springboot/GreetingService.java",
        "src/test/java/com/example/springboot/GreetingServiceTest.java",
    ],
    deps = ["@external://org_springframework_boot_spring_boot_starter_web:3.2.2"],
    args = ["--select-class=com.example.springboot.GreetingServiceTest"],
)

java_lint(
    name = "app_lint",
    srcs = glob(["src/main/java/**/*.java"]),
)

oci_image(
    name = "image",
    binary = ":app",
    base = "ubuntu:22.04",
    env = {"JAVA_OPTS": "-Djava.awt.headless=true"},
    tag = "springboot-example:latest",
)

rbs build app                       # Build the application
rbs run app                         # Run Spring Boot server
rbs test greeting_service_test      # Run specific test
rbs test all_tests                  # Run all tests
rbs build app_lint                  # Lint code
rbs build image                     # Build container image

​Java SDK

​Setup

​Toolchain

​Dependencies

​Rules

​java_library

​java_binary

​java_test

​java_lint

​Example: Spring Boot Application