Generating OpenAPI documentation¶
To use, add the following dependencies:
"com.softwaremill.sttp.tapir" %% "tapir-openapi-docs" % "0.17.9"
"com.softwaremill.sttp.tapir" %% "tapir-openapi-circe-yaml" % "0.17.9"
Tapir contains a case class-based model of the openapi data structures in the openapi/openapi-model
subproject (the
model is independent from all other tapir modules and can be used stand-alone).
An endpoint can be converted to an instance of the model by importing the sttp.tapir.docs.openapi.OpenAPIDocsInterpreter
object:
import sttp.tapir._
import sttp.tapir.openapi.OpenAPI
import sttp.tapir.docs.openapi.OpenAPIDocsInterpreter
val booksListing = endpoint.in(path[String]("bookId"))
val docs: OpenAPI = OpenAPIDocsInterpreter.toOpenAPI(booksListing, "My Bookshop", "1.0")
Such a model can then be refined, by adding details which are not auto-generated. Working with a deeply nested case
class structure such as the OpenAPI
one can be made easier by using a lens library, e.g. Quicklens.
The documentation is generated in a large part basing on schemas. Schemas can be automatically derived and customised.
Quite often, you’ll need to define the servers, through which the API can be reached. To do this, you can modify the
returned OpenAPI
case class either directly or by using a helper method:
import sttp.tapir.openapi.Server
val docsWithServers: OpenAPI = OpenAPIDocsInterpreter.toOpenAPI(booksListing, "My Bookshop", "1.0")
.servers(List(Server("https://api.example.com/v1").description("Production server")))
Multiple endpoints can be converted to an OpenAPI
instance by calling the method on a list of endpoints:
OpenAPIDocsInterpreter.toOpenAPI(List(addBook, booksListing, booksListingByGenre), "My Bookshop", "1.0")
The openapi case classes can then be serialised, either to JSON or YAML using Circe:
import sttp.tapir.openapi.circe.yaml._
println(docs.toYaml)
Options¶
Options can be customised by providing an implicit instance of OpenAPIDocsOptions
, when calling .toOpenAPI
.
operationIdGenerator
: each endpoint corresponds to an operation in the OpenAPI format and should have a unique operation id. By default, thename
of endpoint is used as the operation id, and if this is not available, the operation id is auto-generated by concatenating (using camel-case) the request method and path.
Exposing OpenAPI documentation¶
Exposing the OpenAPI documentation can be very application-specific. However, tapir contains modules which contain akka-http/http4s routes for exposing documentation using Swagger UI or Redoc:
// Akka HTTP
"com.softwaremill.sttp.tapir" %% "tapir-swagger-ui-akka-http" % "0.17.9"
"com.softwaremill.sttp.tapir" %% "tapir-redoc-akka-http" % "0.17.9"
// Finatra
"com.softwaremill.sttp.tapir" %% "tapir-swagger-ui-finatra" % "0.17.9"
// HTTP4S
"com.softwaremill.sttp.tapir" %% "tapir-swagger-ui-http4s" % "0.17.9"
"com.softwaremill.sttp.tapir" %% "tapir-redoc-http4s" % "0.17.9"
// Play
"com.softwaremill.sttp.tapir" %% "tapir-swagger-ui-play" % "0.17.9"
"com.softwaremill.sttp.tapir" %% "tapir-redoc-play" % "0.17.9"
// Vert.x
"com.softwaremill.sttp.tapir" %% "tapir-swagger-ui-vertx" % "0.17.9"
Note: tapir-swagger-ui-akka-http
transitively pulls some Akka modules in version 2.6. If you want to force
your own Akka version (for example 2.5), use sbt exclusion. Mind the Scala version in artifact name:
"com.softwaremill.sttp.tapir" %% "tapir-swagger-ui-akka-http" % "0.17.9" exclude("com.typesafe.akka", "akka-stream_2.12")
Usage example for akka-http:
import sttp.tapir._
import sttp.tapir.docs.openapi.OpenAPIDocsInterpreter
import sttp.tapir.openapi.circe.yaml._
import sttp.tapir.swagger.akkahttp.SwaggerAkka
val myEndpoints: Seq[Endpoint[_, _, _, _]] = ???
val docsAsYaml: String = OpenAPIDocsInterpreter.toOpenAPI(myEndpoints, "My App", "1.0").toYaml
// add to your akka routes
new SwaggerAkka(docsAsYaml).routes
For redoc, use RedocAkkaHttp
.
For http4s, use the SwaggerHttp4s
or RedocHttp4s
classes.
For Play, use SwaggerPlay
or RedocPlay
classes.
For Vert.x, use SwaggerVertx
class.
Using with sbt-assembly¶
The tapir-swagger-ui-*
modules rely on a file in the META-INF
directory tree, to determine the version of the Swagger UI.
You need to take additional measures if you package your application with sbt-assembly
because the default merge strategy of the assembly
task discards most artifacts in that directory.
To avoid a NullPointerException
, you need to include the following file explicitly:
assemblyMergeStrategy in assembly := {
case PathList("META-INF", "maven", "org.webjars", "swagger-ui", "pom.properties") =>
MergeStrategy.singleOrError
case x =>
val oldStrategy = (assemblyMergeStrategy in assembly).value
oldStrategy(x)
}