rules_elide

Bazel rules for Elide — Kotlin / Java compilation, JUnit Platform tests, code formatting, and native-image builds powered by the Elide runtime.

Status: pre-alpha. Public API is unstable. Pin a specific commit or wait for the first tagged release.

Why rules_elide?

Elide consolidates a polyglot runtime, a Kotlin/Java toolchain, formatters (google-java-format, ktfmt), and ahead-of-time native-image into one binary. For Bazel monorepos this means:

• One hermetic toolchain instead of separate rules_java, rules_kotlin, and rules_graalvm toolchains, each with their own JDK pin.
• Native-image and formatters as first-class rules, not separate rulesets.
• One small set of rules to learn (elide_kotlin_library, elide_java_library, elide_native_image, elide_format, ...) instead of three overlapping ecosystems.

Quick start

MODULE.bazel:

bazel_dep(name = "rules_elide", version = "0.0.0")

elide = use_extension("@rules_elide//elide:extensions.bzl", "elide")
elide.install(version = "latest", channel = "nightly")
use_repo(elide, "elide_toolchains")
register_toolchains("@elide_toolchains//:all")

BUILD.bazel:

load("@rules_elide//elide:defs.bzl", "elide_kotlin_binary", "elide_kotlin_library")

elide_kotlin_library(
    name = "lib",
    srcs = glob(["src/main/kotlin/**/*.kt"]),
)

elide_kotlin_binary(
    name = "app",
    srcs = ["Main.kt"],
    main_class = "MainKt",
    deps = [":lib"],
)

bazel run //:app

Rules reference

Rule	Purpose	Reference
elide_java_library	Compile .java sources into a JavaInfo-bearing jar (via elide javac --jar)	docs/java.md
elide_java_binary	_library + launcher (elide java)	docs/java.md
elide_java_test	_library + JUnit Platform launcher	docs/java.md
elide_kotlin_library	Compile mixed .kt / .java sources (via elide kotlinc)	docs/kotlin.md
elide_kotlin_binary	_library + launcher	docs/kotlin.md
elide_kotlin_test	_library + JUnit Platform launcher	docs/kotlin.md
elide_native_image	Native AOT binary from JavaInfo deps (via elide native-image)	docs/native_image.md
elide_format	In-place format .java (google-java-format) or .kt (ktfmt)	docs/format.md
elide_toolchain	Wrap an elide binary as a Bazel toolchain	docs/toolchain.md

Providers: ElideToolchainInfo, ElideInfo (docs/providers.md). Top-level entry point: @rules_elide//elide:defs.bzl.

Toolchain resolution

The elide module extension downloads the elide release artifact for the host platform from the public Elide CDN:

https://elide.zip/artifacts/{channel}/{version}/elide.{os}-{cpu}.{ext}

Each artifact is verified against an in-tree SRI integrity table.

• channel: nightly, preview, or release. Pre-alpha: only nightly and preview are populated upstream.
• version: any concrete revision (e.g. 1.2.0-beta) or the rolling pointer latest. With latest, integrity reflects the snapshot captured in elide/private/versions.bzl; if the CDN advances, regenerate the integrity row.

Supported platforms:

OS	CPU	Constraint
Linux	amd64	@platforms//os:linux + @platforms//cpu:x86_64
Linux	arm64	@platforms//os:linux + @platforms//cpu:aarch64
macOS	arm64	@platforms//os:macos + @platforms//cpu:aarch64

Windows is published on the CDN but not yet supported by these rules — the launcher templates are POSIX sh only. See Roadmap below.

MODULE.bazel.lock records the resolved hashes (the extension marks itself reproducible = True).

Compile-rule outputs (JavaInfo)

Every compile rule returns a complete JavaInfo:

• output_jar — the full class JAR produced by elide javac --jar / elide kotlinc -d.
• compile_jar — ABI jar derived via java_common.run_ijar for fast downstream incremental rebuilds.
• source_jars — sources packaged via java_common.pack_sources (IDE sync / Maven publish friendly).

JUnit Platform tests

elide_java_test and elide_kotlin_test launch the JUnit Platform ConsoleLauncher. The launcher honours Bazel's test runner contract: TEST_TMPDIR, XML_OUTPUT_FILE, and TEST_FILTER. Reports written to $TEST_TMPDIR/reports/ are merged into $XML_OUTPUT_FILE post-run.

Consumer requirement: place org.junit.platform:junit-platform-console-standalone on the test classpath via runtime_deps (typically through rules_jvm_external).

Use test_class = "<fqcn>" to select a single class; leave empty to scan the classpath.

Code formatting

load("@rules_elide//elide:defs.bzl", "elide_format")

elide_format(
    name = "format",
    srcs = glob(["src/**/*.kt"]) + glob(["src/**/*.java"]),
)

bazel run //:format formats files in place. Java sources route through google-java-format; .kt/.kts route through ktfmt. A single target may not mix languages — split into two elide_format targets if needed.

Hermetic and RBE / Buildfarm compatible

• No host JDK detection. No repository_ctx.which. The full extracted elide distribution is declared as runfiles of the toolchain.
• Platform-resolved via @platforms//os:* + @platforms//cpu:*.
• All file paths are relative; no developer-machine paths leak into outputs. Should run unchanged under Buildfarm, BuildBuddy RBE, or EngFlow remote execution.

How it compares

If you currently use…	Migrate to rules_elide for…
rules_java	Faster compile in steady state (~2.8x on micro-bench), JUnit 5 native, ABI ijar + source jars
rules_kotlin	Faster compile (~5.5x on micro-bench), compile-time-compatible JavaInfo, single Elide JDK
rules_graalvm	Native-image without a separate toolchain or GraalVM SDK download

rules_elide returns JavaInfo from every compile rule, so existing java_library / kt_jvm_library consumers can depend on elide_* targets unchanged.

See benchmarks/RESULTS.md for methodology, recorded numbers, and how to reproduce locally via ./benchmarks/bench.sh.

Local development against a non-released elide

To validate the smoke workspace against a locally-built elide binary, point ELIDE_DEV_BIN at the binary and enable --config=dev in e2e/smoke/:

ELIDE_DEV_BIN=/abs/path/to/elide bazel build //... --config=dev
ELIDE_DEV_BIN=/abs/path/to/elide bazel test  //... --config=dev

See e2e/smoke/README.md for the full flow.

Roadmap

Item	Status
Persistent worker protocol	Pending Elide CLI WorkRequest/WorkResponse support
elide native-image under Bazel	Blocked on upstream Elide CLI JavaCommand NPE under sandbox env
Kotlin srcjars (extract+compile)	Pending
Stable release channel populated	Pending upstream
BCR (Bazel Central Registry)	Templates in .bcr/; first publication after release

Compatibility

Layer	Status
Bazel	7.4.0+ (Bzlmod-only; legacy WORKSPACE is not supported)

Versioning

Semantic versioning. compatibility_level = 1 until a hard API break.

License

Apache 2.0. See LICENSE.

Contributing

See CONTRIBUTING.md.