ZIO integration

The tapir-zio module defines type aliases and extension methods which make it more ergonomic to work with ZIO and tapir. Moreover, the tapir-zio-http4s-server contains an interpreter useful when exposing the endpoints using the http4s server.

You’ll need the following dependencies:

"com.softwaremill.sttp.tapir" %% "tapir-zio" % "0.17.1"
"com.softwaremill.sttp.tapir" %% "tapir-zio-http4s-server" % "0.17.1"

Next, instead of the usual import sttp.tapir._, you should import:

import sttp.tapir.ztapir._

This brings into scope all of the basic input/output descriptions, which can be used to define an endpoint. Additionally, it defines the ZEndpoint type alias, which should be used instead of Endpoint.


You should have only one of these imports in your source file. Otherwise, you’ll get naming conflicts. The import sttp.tapir.ztapir._ import is meant as a complete replacement of import sttp.tapir._.

Server logic

When defining the business logic for an endpoint, the following methods are available, which replace the standard ones:

  • def zServerLogic(logic: I => ZIO[R, E, O]): ZServerEndpoint[R, I, E, O]
  • def zServerLogicPart(logicPart: T => ZIO[R, E, U])
  • def zServerLogicForCurrent(logicPart: I => ZIO[R, E, U])

The first defines complete server logic, while the second and third allow defining server logic in parts.

Exposing endpoints using the http4s server

To interpret a ZServerEndpoint as a http4s server, add the following import:

import sttp.tapir.server.http4s.ztapir.ZHttp4sServerInterpreter

This adds the following method on ZEndpoint:

  • def toRoutes[R](logic: I => ZIO[R, E, O]): HttpRoutes[ZIO[R with Clock, Throwable, *]]

And the following methods on ZServerEndpoint or List[ZServerEndpoint]:

  • def toRoutes[R]: HttpRoutes[ZIO[R with Clock, Throwable, *]]

Note that the resulting HttpRoutes always require a clock in their environment.

If you have multiple endpoints with different environmental requirements, the environment must be first widened so that it is uniform across all endpoints, using the .widen method:

import org.http4s.HttpRoutes
import sttp.tapir.ztapir._
import sttp.tapir.server.http4s.ztapir.ZHttp4sServerInterpreter
import zio.{Has, RIO, ZIO}
import zio.clock.Clock
import zio.interop.catz._

trait Component1
trait Component2
type Service1 = Has[Component1]
type Service2 = Has[Component2]

val serverEndpoint1: ZServerEndpoint[Service1, Unit, Unit, Unit] = ???                                                            
val serverEndpoint2: ZServerEndpoint[Service2, Unit, Unit, Unit] = ???

type Env = Service1 with Service2
val routes: HttpRoutes[RIO[Env with Clock, *]] = 
  )).toRoutes // this is where zio-cats interop is needed


Three examples of using the ZIO integration are available. The first two showcase basic functionality, while the third shows how to use partial server logic methods: