Kairo Server

Servers are composed of Features, and can be run as an application or as part of integration tests.

A Server manages the full lifecycle of its Features: starting them in priority order, running them together, and stopping them gracefully on shutdown.

Installation

Install kairo-server. But if you’ve already installed kairo-application, you don’t need kairo-server too.

build.gradle.kts

dependencies {
  implementation("com.highbeam.kairo:kairo-server")
}

Usage

All you need are your Features and a name.

val features = listOf(
  DependencyInjectionFeature(koinApplication),
  HealthCheckFeature(healthChecks),
  RestFeature(config.rest),
  SqlFeature(config.sql, configureDatabase = { explicitDialect = PostgreSQLDialect() }),
  UserFeature(koinApplication.koin),
)

val server = Server(
  name = "My Application",
  features = features,
)

You can run the Server as an application using kairo-application, or use it in integration tests.

Lifecycle

On startup, the Server groups all Feature lifecycle handlers by priority and starts each group sequentially (lowest priority first). Features within the same priority group start in parallel.

On shutdown, the Server stops Features in reverse priority order. Shutdown uses supervisorScope, meaning all Features get a chance to clean up even if one fails to stop.

If a Feature fails during startup, the Server rolls back by stopping all Features that already started.

See kairo-feature for details on lifecycle handlers and priorities.

Server state

A Server progresses through these states: Default → Starting → Running → Stopping → Default. The state property is volatile and can be read without synchronization.