From 5ec270aa98b806f32338fa25357abdf45dd0625b Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jakob@driver.xyz>
Date: Wed, 22 Aug 2018 12:51:36 -0700
Subject: Trait-based initialization and other utilities

Adds the concept of a 'platform', a centralized place in which
environment-specific information will be managed, and provides common
initialization logic for most "standard" apps.

As part of the common initialization, other parts of core have also
been reworked:

- HTTP-related unmarshallers and path matchers have been factored out
  from core.json to a new core.rest.directives package (core.json
  extends those unmarshallers and matchers for backwards
  compatibility)

- CORS handling has also been moved to a dedicated utility trait

- Some custom headers have been moved from raw headers to typed ones
  in core.rest.headers

- The concept of a "reporter" has been introduced. A reporter is a
  context-aware combination of tracing and logging. It is intended to
  issue diagnostic messages that can be traced across service
  boundaries.

Closes #192
Closes #195
---
 src/main/scala/xyz/driver/core/init/HttpApi.scala | 89 +++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 src/main/scala/xyz/driver/core/init/HttpApi.scala

(limited to 'src/main/scala/xyz/driver/core/init/HttpApi.scala')

diff --git a/src/main/scala/xyz/driver/core/init/HttpApi.scala b/src/main/scala/xyz/driver/core/init/HttpApi.scala
new file mode 100644
index 0000000..6ea3d51
--- /dev/null
+++ b/src/main/scala/xyz/driver/core/init/HttpApi.scala
@@ -0,0 +1,89 @@
+package xyz.driver.core
+package init
+
+import akka.http.scaladsl.marshallers.sprayjson.SprayJsonSupport
+import akka.http.scaladsl.server.{RequestContext, Route, RouteConcatenation}
+import spray.json.DefaultJsonProtocol._
+import spray.json._
+import xyz.driver.core.rest.Swagger
+import xyz.driver.core.rest.directives.Directives
+import akka.http.scaladsl.model.headers._
+import xyz.driver.core.reporting.Reporter.CausalRelation
+import xyz.driver.core.reporting.SpanContext
+import xyz.driver.core.rest.headers.Traceparent
+
+import scala.collection.JavaConverters._
+
+/** Mixin trait that provides some well-known HTTP endpoints, diagnostic header injection and forwarding,
+  * and exposes an application-specific route that must be implemented by services.
+  * @see ProtobufApi
+  */
+trait HttpApi extends CloudServices with Directives with SprayJsonSupport { self =>
+
+  /** Route that handles the application's business logic.
+    * @group hooks
+    */
+  def applicationRoute: Route
+
+  /** Classes with Swagger annotations.
+    * @group hooks
+    */
+  def swaggerRouteClasses: Set[Class[_]]
+
+  private val healthRoute = path("health") {
+    complete(Map("status" -> "good").toJson)
+  }
+
+  private val versionRoute = path("version") {
+    complete(Map("name" -> self.name.toJson, "version" -> self.version.toJson).toJson)
+  }
+
+  private lazy val swaggerRoute = {
+    val generator = new Swagger(
+      "",
+      "https" :: "http" :: Nil,
+      self.version.getOrElse("<unknown>"),
+      swaggerRouteClasses,
+      config,
+      reporter
+    )
+    generator.routes ~ generator.swaggerUI
+  }
+
+  private def cors(inner: Route): Route =
+    cors(
+      config.getStringList("application.cors.allowedOrigins").asScala.toSet,
+      xyz.driver.core.rest.AllowedHeaders
+    )(inner)
+
+  private def traced(inner: Route): Route = (ctx: RequestContext) => {
+    val tags = Map(
+      "service_name"    -> name,
+      "service_version" -> version.getOrElse("<unknown>"),
+      "http_user_agent" -> ctx.request.header[`User-Agent`].map(_.value).getOrElse("<unknown>"),
+      "http_uri"        -> ctx.request.uri.toString,
+      "http_path"       -> ctx.request.uri.path.toString
+    )
+    val parent = ctx.request.header[Traceparent].map { p =>
+      SpanContext(p.traceId, p.spanId) -> CausalRelation.Child
+    }
+    reporter.traceWithOptionalParentAsync("handle_service_request", tags, parent) { sctx =>
+      val header     = Traceparent(sctx.traceId, sctx.spanId)
+      val withHeader = ctx.withRequest(ctx.request.withHeaders(header))
+      inner(withHeader)
+    }
+  }
+
+  /** Extended route. */
+  override lazy val route: Route = traced(
+    cors(
+      RouteConcatenation.concat(
+        healthRoute,
+        versionRoute,
+        swaggerRoute,
+        applicationRoute
+      )
+    )
+  )
+
+}
-- 
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