rightsize

Testcontainers-style integration testing on microVMs. No Docker required.

rightsize runs your integration-test containers as hardware-isolated microsandbox microVMs — with a Testcontainers-shaped Kotlin API, a self-provisioning runtime (one Gradle dependency, zero install steps), and a Docker fallback for platforms microVMs can't reach.

@Sandboxed
class OrderServiceTest {
    companion object {
        @JvmStatic @Container
        val redis = RedisContainer()          // boots a real microVM

        @JvmStatic @Container
        val kafka = RedpandaContainer()
    }

    @Test
    fun `orders flow end to end`() {
        val client = RedisClient.create(redis.uri)   // 127.0.0.1:<mapped port>
        val producer = KafkaProducer<String, String>(props(kafka.bootstrapServers))
        // ... your test
    }
}

If you know Testcontainers, you already know this API — that's deliberate.

Why rightsize

Hardware-level isolation (a microVM per container), no Docker daemon or Desktop license, and a runtime that installs itself on first use — at the same end-to-end speed as Docker on a real Spring Boot suite (164 s vs 165 s, fourteen test classes, same machine). The pitch isn't "faster than Docker"; it's "as fast as Docker, with hardware isolation and nothing to install."

The full comparison table, benchmark methodology, and platform matrix live in the project README — this site doesn't repeat them. In one line: Apple Silicon macs, Linux-with-KVM, and Windows-with-WHP get microVMs; everything else falls back to Docker automatically, and tests run unchanged on either backend. Backend-specific edges are covered in Backends.

Where to go next

• New to rightsize? Start with Getting Started — dependency setup, your first @Sandboxed test, and what happens on first run.
• Want to run something first? examples/ in the repo has three runnable examples (plain API, @Sandboxed JUnit, multi-container networking) — see the project README's Examples section for the exact commands.
• Need a specific container? Jump to Modules for the full catalog with copy-paste test examples.
• Something not working? Check Troubleshooting first — it's built from real failures hit while building rightsize itself.
• Running rightsize in more than one language? See Cross-Language Parity — the same container spec behaves the same way in rightsize's Kotlin, Rust, and Node libraries.

Status

On Maven Central under the group dev.rightsize. See Getting Started for the coordinates.

License

Apache-2.0