tapir, or Typed API descRiptions

With tapir you can describe HTTP API endpoints as immutable Scala values. Each endpoint can contain a number of input parameters, error-output parameters, and normal-output parameters. An endpoint specification can be interpreted as:

• a server, given the “business logic”: a function, which computes output parameters based on input parameters. Currently supported:
  • Akka HTTP Routes/Directives.
  • Http4s HttpRoutes[F]
  • Finatra http.Controller
• a client, which is a function from input parameters to output parameters. Currently supported: sttp.
• documentation. Currently supported: OpenAPI.

Tapir is licensed under Apache2, the source code is available of GitHub.

Depending on how you prefer to explore the library, take a look at one of the examples or read on for a more detailed description of how tapir works!

Code teaser

import sttp.tapir._
import sttp.tapir.json.circe._
import io.circe.generic.auto._

type Limit = Int
type AuthToken = String
case class BooksFromYear(genre: String, year: Int)
case class Book(title: String)

val booksListing: Endpoint[(BooksFromYear, Limit, AuthToken), String, List[Book], Nothing] = 
  endpoint
    .get
    .in(("books" / path[String]("genre") / path[Int]("year")).mapTo(BooksFromYear))
    .in(query[Limit]("limit").description("Maximum number of books to retrieve"))
    .in(header[AuthToken]("X-Auth-Token"))
    .errorOut(stringBody)
    .out(jsonBody[List[Book]])

//

import sttp.tapir.docs.openapi._
import sttp.tapir.openapi.circe.yaml._

val docs = booksListing.toOpenAPI("My Bookshop", "1.0")
println(docs.toYaml)

//

import sttp.tapir.server.akkahttp._
import akka.http.scaladsl.server.Route
import scala.concurrent.Future

def bookListingLogic(bfy: BooksFromYear, 
                     limit: Limit,  
                     at: AuthToken): Future[Either[String, List[Book]]] =
  Future.successful(Right(List(Book("The Sorrows of Young Werther"))))
val booksListingRoute: Route = booksListing.toRoute(bookListingLogic _)

//

import sttp.tapir.client.sttp._
import com.softwaremill.sttp._

val booksListingRequest: Request[Either[String, List[Book]], Nothing] = booksListing
  .toSttpRequest(uri"http://localhost:8080")
  .apply(BooksFromYear("SF", 2016), 20, "xyz-abc-123")

Contents

• Quickstart
• Examples
• Goals of the project
• Endpoints: basics
• Endpoints: inputs/outputs
• Endpoints: status codes
• Endpoints: codecs
• Endpoints: custom types
• Endpoints: validation
• Endpoints: working with JSON
• Endpoints: forms
• Endpoints: authentication
• Servers: akka-http interpreter
• Servers: http4s interpreter
• Servers: finatra interpreter
• Servers: options
• Servers: logic
• Servers: error handling
• Servers: debugging
• Clients: sttp client interpreter
• Other interpreters
• Documentation: openapi interpreter
• Create your own tapir
• Contributing

Other sttp projects

sttp is a family of Scala HTTP-related projects, and currently includes:

• sttp client: the Scala HTTP client you always wanted!
• sttp tapir: this project
• sttp model: simple HTTP model classes (used by client & tapir)