Allow plugins to inject their own routes into API (#1805)

Plugins can extend the `RouteProvider` trait to enrich the API with
custom calls, removing the need to setup a separate endpoint on a
different port.

When routes clash between plugins, the second one is simply ignored.
Plugin developers should prepend their route with their plugin name
to avoid such silent clashes.

eclair-node/src/main/scala/fr/acinq/eclair/Boot.scala

@@ -20,7 +20,8 @@ import java.io.File
 
 import akka.actor.ActorSystem
 import akka.http.scaladsl.Http
-import akka.stream.{ActorMaterializer, BindFailedException}
+import akka.http.scaladsl.server.Route
+import akka.stream.BindFailedException
 import fr.acinq.eclair.api.Service
 import grizzled.slf4j.Logging
 import kamon.Kamon
@@ -50,7 +51,8 @@ object Boot extends App with Logging {
     plugins.foreach(_.onSetup(setup))
     setup.bootstrap onComplete {
       case Success(kit) =>
-        startApiServiceIfEnabled(kit)
+        val routeProviderPlugins = plugins.collect { case plugin: RouteProvider => plugin }
+        startApiServiceIfEnabled(kit, routeProviderPlugins)
         plugins.foreach(_.onKit(kit))
       case Failure(t) => onError(t)
     }
@@ -65,22 +67,21 @@ object Boot extends App with Logging {
    * @param system
    * @param ec
    */
-  def startApiServiceIfEnabled(kit: Kit)(implicit system: ActorSystem, ec: ExecutionContext) = {
+  def startApiServiceIfEnabled(kit: Kit, providers: Seq[RouteProvider] = Nil)(implicit system: ActorSystem, ec: ExecutionContext) = {
     val config = system.settings.config.getConfig("eclair")
     if (config.getBoolean("api.enabled")) {
       logger.info(s"json API enabled on port=${config.getInt("api.port")}")
-      implicit val materializer = ActorMaterializer()
       val apiPassword = config.getString("api.password") match {
         case "" => throw EmptyAPIPasswordException
         case valid => valid
       }
-      val apiRoute = new Service {
-        override val actorSystem = system
-        override val mat = materializer
-        override val password = apiPassword
+      val service: Service = new Service {
+        override val actorSystem: ActorSystem = system
+        override val password: String = apiPassword
         override val eclairApi: Eclair = new EclairImpl(kit)
-      }.route
-      Http().bindAndHandle(apiRoute, config.getString("api.binding-ip"), config.getInt("api.port")).recover {
+      }
+      val pluginRoutes = providers.map(_.route(service))
+      Http().bindAndHandle(service.finalRoutes(pluginRoutes), config.getString("api.binding-ip"), config.getInt("api.port")).recover {
         case _: BindFailedException => onError(TCPBindException(config.getInt("api.port")))
       }
     } else {

eclair-node/src/main/scala/fr/acinq/eclair/Plugin.scala

@@ -18,7 +18,11 @@ package fr.acinq.eclair
 
 import java.io.File
 import java.net.{JarURLConnection, URL, URLClassLoader}
+
+import akka.http.scaladsl.server.Route
+import fr.acinq.eclair.api.directives.EclairDirectives
 import grizzled.slf4j.Logging
+
 import scala.util.{Failure, Success, Try}
 
 trait Plugin {
@@ -28,7 +32,10 @@ trait Plugin {
   def onSetup(setup: Setup): Unit
 
   def onKit(kit: Kit): Unit
+}
 
+trait RouteProvider {
+  def route(directives: EclairDirectives): Route
 }
 
 object Plugin extends Logging {

eclair-node/src/main/scala/fr/acinq/eclair/api/Service.scala

@@ -18,7 +18,6 @@ package fr.acinq.eclair.api
 
 import akka.actor.ActorSystem
 import akka.http.scaladsl.server._
-import akka.stream.Materializer
 import fr.acinq.eclair.Eclair
 import fr.acinq.eclair.api.directives.EclairDirectives
 import fr.acinq.eclair.api.handlers._
@@ -41,18 +40,12 @@ trait Service extends EclairDirectives with WebSocket with Node with Channel wit
    */
   implicit val actorSystem: ActorSystem
 
-  /**
-   * Materializer for sending and receiving tcp streams.
-   */
-  implicit val mat: Materializer
-
   /**
    * Collect routes from all sub-routers here.
    * This is the main entrypoint for the global http request router of the API service.
    * This is where we handle errors to ensure all routes are correctly tried before rejecting.
    */
-  val route: Route = securedHandler {
-    nodeRoutes ~ channelRoutes ~ feeRoutes ~ pathFindingRoutes ~ invoiceRoutes ~ paymentRoutes ~ messageRoutes ~ onChainRoutes ~ webSocket
+  def finalRoutes(extraRoutes: Seq[Route]): Route = securedHandler {
+    extraRoutes.foldLeft(nodeRoutes ~ channelRoutes ~ feeRoutes ~ pathFindingRoutes ~ invoiceRoutes ~ paymentRoutes ~ messageRoutes ~ onChainRoutes ~ webSocket)(_ ~ _)
   }
-
 }

eclair-node/src/main/scala/fr/acinq/eclair/api/directives/EclairDirectives.scala

@@ -22,7 +22,7 @@ import fr.acinq.eclair.api.Service
 
 import scala.concurrent.duration.DurationInt
 
-class EclairDirectives extends Directives with TimeoutDirective with ErrorDirective with AuthDirective with DefaultHeaders with ExtraDirectives {
+trait EclairDirectives extends Directives with TimeoutDirective with ErrorDirective with AuthDirective with DefaultHeaders with ExtraDirectives {
   this: Service =>
 
   /**

eclair-node/src/test/scala/fr/acinq/eclair/api/ApiServiceSpec.scala

@@ -16,13 +16,14 @@
 
 package fr.acinq.eclair.api
 
+import java.util.UUID
+
 import akka.actor.{ActorRef, ActorSystem}
 import akka.http.scaladsl.model.FormData
 import akka.http.scaladsl.model.StatusCodes._
 import akka.http.scaladsl.model.headers.BasicHttpCredentials
 import akka.http.scaladsl.server.Route
 import akka.http.scaladsl.testkit.{RouteTestTimeout, ScalatestRouteTest, WSProbe}
-import akka.stream.Materializer
 import akka.util.Timeout
 import de.heikoseeberger.akkahttpjson4s.Json4sSupport
 import fr.acinq.bitcoin.Crypto.PublicKey
@@ -31,7 +32,7 @@ import fr.acinq.eclair.ApiTypes.ChannelIdentifier
 import fr.acinq.eclair.FeatureSupport.{Mandatory, Optional}
 import fr.acinq.eclair.Features.{ChannelRangeQueriesExtended, OptionDataLossProtect}
 import fr.acinq.eclair._
-import fr.acinq.eclair.api.directives.ErrorResponse
+import fr.acinq.eclair.api.directives.{EclairDirectives, ErrorResponse}
 import fr.acinq.eclair.api.serde.JsonSupport
 import fr.acinq.eclair.blockchain.fee.FeeratePerKw
 import fr.acinq.eclair.channel.ChannelOpenResponse.ChannelOpened
@@ -52,7 +53,6 @@ import org.scalatest.funsuite.AnyFunSuite
 import org.scalatest.matchers.should.Matchers
 import scodec.bits._
 
-import java.util.UUID
 import scala.concurrent.Future
 import scala.concurrent.duration._
 import scala.io.Source
@@ -68,13 +68,29 @@ class ApiServiceSpec extends AnyFunSuite with ScalatestRouteTest with IdiomaticM
   val aliceNodeId = PublicKey(hex"03af0ed6052cf28d670665549bc86f4b721c9fdb309d40c58f5811f63966e005d0")
   val bobNodeId = PublicKey(hex"039dc0e0b1d25905e44fdf6f8e89755a5e219685840d0bc1d28d3308f9628a3585")
 
+  object PluginApi extends RouteProvider {
+    override def route(directives: EclairDirectives): Route = {
+      import directives._
+      val route1 = postRequest("plugin-test") { implicit t =>
+        complete("fine")
+      }
+
+      val route2 = postRequest("payinvoice") { implicit t =>
+        complete("gets overridden by base API endpoint")
+      }
+
+      route1 ~ route2
+    }
+  }
+
   class MockService(eclair: Eclair) extends Service {
     override val eclairApi: Eclair = eclair
 
     override def password: String = "mock"
 
     override implicit val actorSystem: ActorSystem = system
-    override implicit val mat: Materializer = materializer
+
+    val route: Route = finalRoutes(Seq(PluginApi.route(this)))
   }
 
   def mockApi(eclair: Eclair = mock[Eclair]): MockService = {
@@ -170,6 +186,17 @@ class ApiServiceSpec extends AnyFunSuite with ScalatestRouteTest with IdiomaticM
       }
   }
 
+  test("plugin injects its own route") {
+    Post("/plugin-test") ~>
+      addCredentials(BasicHttpCredentials("", mockApi().password)) ~>
+      Route.seal(mockApi().route) ~>
+      check {
+        assert(handled)
+        assert(status == OK)
+        assert(entityAs[String] == "fine")
+      }
+  }
+
   test("'usablebalances' asks relayer for current usable balances") {
     val eclair = mock[Eclair]
     eclair.usableBalances()(any[Timeout]) returns Future.successful(List(