Crate kerniq_server 

Kerniq Server

A lightweight, asynchronous web framework for Rust: the approachability of Flask on top of Axum, Tower, Hyper and Tokio.

use kerniq_server::prelude::*;

#[tokio::main]
async fn main() -> Result<()> {
    App::new()
        .get("/", || async { "Hello from Kerniq" })
        .run("127.0.0.1:3000")
        .await
}

What Kerniq adds, and what it reuses

Kerniq is a thin ergonomic layer. Routing, extraction and HTTP are Axum’s; middleware is Tower’s; the protocol is Hyper’s; execution is Tokio’s. Kerniq contributes:

• the App builder: Flask-style route registration, typed state, configuration, lifecycle (graceful shutdown, background tasks, connection and concurrency limits) in one place,
• Router with prefixes, groups and mounting,
• middleware that applies to every route regardless of declaration order, with first-declared-is-outermost ordering,
• one JSON error envelope for application errors, malformed input, 404/405, timeouts, rate limiting and authentication failures,
• production middleware (logging, request IDs, CORS, compression, timeouts, rate limiting, auth extension points, metrics),
• optional OpenAPI, validation and WebSocket support.

Handlers are plain Axum handlers, and the app converts to an axum::Router with App::into_axum_router, so the Axum and Tower ecosystems stay fully available.

Crate features

Feature	Default	Enables
json	✓	Json<T>, Created<T>
tracing	✓	Logger middleware
cors		Cors middleware
compression		Compression middleware
websocket		extract::ws
openapi		openapi module (Utoipa + Swagger UI)
validation		ValidatedJson, ValidatedQuery
config-file		ServerConfig::from_file (TOML)
macros		authorize attribute for role/permission checks
full		all of the above
observability		App::observability, observability module
observability-metrics		OpenTelemetry metrics, HTTP metrics
observability-logs		JSON / pretty console logs, log export
observability-tracing		distributed tracing, W3C propagation
otlp / otlp-tls		OTLP export to a Collector or backend
prometheus		Prometheus scrape endpoint
runtime-metrics		Tokio and process metrics
full-observability		all observability features except otlp-tls

Re-exports

pub use axum;

pub use http;

pub use tower;

Modules

config

Server configuration. See ServerConfig.

error

The error model. See Error.

extract

Request extractors.

middleware

Middleware: the composition traits and the built-in middleware.

observabilityobservability

Kerniq Observe: metrics, logs and traces (feature observability). See App::observability.

openapiopenapi

OpenAPI documents and Swagger UI (feature openapi).

prelude

Everything most applications need: use kerniq_server::prelude::*;

response

Response types.

routing

Routers, groups and method routers.

runtime

Server lifecycle: shutdown handles, background tasks and runtime helpers.

Structs

App

A Kerniq application: routes, state, middleware, configuration and lifecycle in one builder.

Error

The framework error type.

Type Aliases

Result

A Result whose error type defaults to the Kerniq Error.

Attribute Macros

authorizemacros

Protects a handler with a role or permission rule, in the spirit of Spring’s @PreAuthorize.