Ktor Swagger-UI

This library provides a Ktor plugin to document routes, generate an OpenApi Specification and serve a Swagger UI. It is meant to be minimally invasive, meaning it can be plugged into existing application without requiring immediate changes to the code. Routes can then be gradually enhanced with documentation.

Features

minimally invasive (no immediate change to existing code required)
provides swagger-ui with no initial configuration required
supports most of the OpenAPI 3.0.3 Specification
automatic json-schema generation from arbitrary types/classes for bodies and parameters
use custom encoder/serializers for examples and json-schemas
provide custom schemas or a custom schema-builder
external/custom json-schemas for bodies
protect Swagger-UI and OpenApi-Spec with custom authentication

Documentation

A wiki with a short documentation is available here.

Installation

dependencies {
    implementation "io.github.smiley4:ktor-swagger-ui:<VERSION>"
}

Example

Full examples can be found in src/test/examples.

Configuration

install(SwaggerUI) {
    swagger {
        swaggerUrl = "swagger-ui"
        forwardRoot = true
    }
    info {
        title = "Example API"
        version = "latest"
        description = "Example API for testing and demonstration purposes."
    }
    server {
        url = "http://localhost:8080"
        description = "Development Server"
    }
}

Routes

get("hello", {
    description = "Hello World Endpoint."
    response {
        HttpStatusCode.OK to {
            description = "Successful Request"
            body<String> { description = "the response" }
        }
        HttpStatusCode.InternalServerError to {
            description = "Something unexpected happened"
        }
    }
}) {
    call.respondText("Hello World!")
}

post("math/{operation}", {
    tags = listOf("test")
    description = "Performs the given operation on the given values and returns the result"
    request {
        pathParameter<String>("operation") {
            description = "the math operation to perform. Either 'add' or 'sub'"
        }
        body<MathRequest>()
    }
    response {
        HttpStatusCode.OK to {
            description = "The operation was successful"
            body<MathResult> {
                description = "The result of the operation"
            }
        }
        HttpStatusCode.BadRequest to {
            description = "An invalid operation was provided"
        }
    }
}) {
    val operation = call.parameters["operation"]!!
    call.receive<MathRequest>().let { request ->
        when (operation) {
            "add" -> call.respond(HttpStatusCode.OK, MathResult(request.a + request.b))
            "sub" -> call.respond(HttpStatusCode.OK, MathResult(request.a - request.b))
            else -> call.respond(HttpStatusCode.BadRequest, Unit)
        }
    }
}

data class MathRequest(
    val a: Int,
    val b: Int
)

data class MathResult(
    val value: Int
)