With tapir, you can describe HTTP API endpoints as immutable Scala values. Each endpoint can contain a number of input and 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]
  • Netty
  • Finatra FinatraRoute
  • Play Route
  • Vert.X Router => Route
  • ZIO Http Http
  • Armeria HttpServiceWithRoutes
  • aws through Lambda/SAM/Terraform
• a client, which is a function from input parameters to output parameters. Currently supported:
  • sttp
  • Play
  • http4s
• documentation. Currently supported:
  • OpenAPI
  • AsyncAPI

Depending on how you prefer to explore the library, take a look at one of the examples or head over to the docs for a more detailed description of how tapir works! Or, use adopt-tapir to generate a tapir-based project in a couple of clicks!

• type-safety: compile-time guarantees, develop-time completions, read-time information
• declarative: separate the shape of the endpoint (the "what"), from the server logic (the "how")
• OpenAPI / Swagger integration: generate documentation from endpoint descriptions
• observability: leverage the metadata to report rich metrics and tracing information
• abstraction: re-use common endpoint definitions, as well as individual inputs/outputs
• library, not a framework: integrates with your stack

Is your company already using tapir? We're continually expanding the "adopters" section in the documentation; the more the merrier! It would be great to feature your company's logo, but in order to do that, we'll need written permission to avoid any legal misunderstandings.

Please email us at [email protected] from your company's email with a link to your logo (if we can use it, of course!) or with details who to kindly ask for permission to feature the logo in tapir's documentation. We'll handle the rest.

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

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


// Define an endpoint

val booksListing: PublicEndpoint[(BooksQuery, Limit, AuthToken), String, List[Book], Any] = 
  endpoint
    .get
    .in(("books" / path[String]("genre") / path[Int]("year")).mapTo[BooksQuery])
    .in(query[Limit]("limit").description("Maximum number of books to retrieve"))
    .in(header[AuthToken]("X-Auth-Token"))
    .errorOut(stringBody)
    .out(jsonBody[List[Book]])


// Generate OpenAPI documentation

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

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


// Convert to akka-http Route

import sttp.tapir.server.akkahttp.AkkaHttpServerInterpreter
import akka.http.scaladsl.server.Route
import scala.concurrent.Future
import scala.concurrent.ExecutionContext.Implicits.global

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


// Convert to sttp Request

import sttp.tapir.client.sttp.SttpClientInterpreter
import sttp.client3._

val booksListingRequest: Request[DecodeResult[Either[String, List[Book]]], Any] = 
  SttpClientInterpreter()
    .toRequest(booksListing, Some(uri"http://localhost:8080"))
    .apply((BooksQuery("SF", 2016), 20, "xyz-abc-123"))

tapir documentation is available at tapir.softwaremill.com.

Add the following dependency:

"com.softwaremill.sttp.tapir" %% "tapir-core" % "1.0.4"

Then, import:

import sttp.tapir._

And finally, type endpoint. and see where auto-complete gets you!

Partial unification is now enabled by default from Scala 2.13. However, if you're using Scala 2.12 or older, then you'll need partial unification enabled in the compiler (alternatively, you'll need to manually provide type arguments in some cases):

scalacOptions += "-Ypartial-unification"

Sidenote for scala 2.12.4 and higher: if you encounter an issue with compiling your project because of a StackOverflowException related to this scala bug, please increase your stack memory. Example:

sbt -J-Xss4M clean compile

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)
• sttp shared: shared web socket, FP abstractions, capabilities and streaming code.
• sttp apispec: OpenAPI, AsyncAPI and JSON Schema models.

All suggestions welcome :)

See the list of issues and pick one! Or report your own.

If you are having doubts on the why or how something works, don't hesitate to ask a question on gitter or via github. This probably means that the documentation, scaladocs or code is unclear and be improved for the benefit of all.

The JS tests use Gecko instead of Chrome, although this causes another problem: out of memory when running JS tests for multiple modules. Work-arounds:

• run only JVM tests for a specific Scala version using testJVM2_13
• test single JS projects
• use CI (GitHub Actions) to test all projects - the .github/workflows/ci.yml enumerates them one by one

You can test only server/client/doc/other projects using testServers, testClients, testDocs and testOther.

To verify that the code snippet in docs compile, run compileDocumentation. A full mdoc run is done during a release (when the documentation is generated).

We offer commercial support for tapir and related technologies, as well as development services. Contact us to learn more about our offer!

Copyright (C) 2018-2022 SoftwareMill https://softwaremill.com.