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Move span creation to middleware
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@msosnicki
msosnicki committed Jun 6, 2023
1 parent 300082d commit a80c6a9
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Showing 3 changed files with 82 additions and 97 deletions.
80 changes: 68 additions & 12 deletions modules/http4s/src/main/scala/natchez/http4s/NatchezMiddleware.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -10,13 +10,27 @@ import cats.effect.{MonadCancel, Outcome}
import cats.effect.syntax.all._
import Outcome._
import org.http4s.HttpRoutes
import natchez.{Trace, TraceValue, Tags}
import org.typelevel.ci.CIString
import natchez.{Kernel, Span, Trace, TraceValue, Tags}
import org.http4s.Request
import org.http4s.Response
import org.http4s.client.Client
import java.io.ByteArrayOutputStream
import java.io.PrintStream
import cats.effect.Resource

/**
* @define excludedHeaders
* All headers except security (Authorization, Cookie, Set-Cookie)
* and payload (Content-Length, ContentType, Content-Range, Trailer, Transfer-Encoding)
* are passed to Kernel by default.
*
* @define isKernelHeader should an HTTP header be passed to Kernel or not
*
* @define spanName compute the span name from the request
*
* @define modifySpanOptions modify default span creation options
*/
object NatchezMiddleware {
import syntax.kernel._

Expand All @@ -27,7 +41,8 @@ object NatchezMiddleware {
server(routes)

/**
* A middleware that adds the following standard fields to the current span:
* A middleware that creates a per request span.
* It also adds following standard fields to newly created span:
*
* - "http.method" -> "GET", "PUT", etc.
* - "http.url" -> request URI (not URL)
Expand All @@ -39,8 +54,20 @@ object NatchezMiddleware {
* - "error.message" -> Exception message
* - "error.stacktrace" -> Exception stack trace as a multi-line string
* - "cancelled" -> true // only present in case of cancellation
*
* @note $excludedHeaders
*
* @param isKernelHeader $isKernelHeader
* @param spanName $spanName
* @param modifySpanOptions $modifySpanOptions
*/
def server[F[_]: Trace](routes: HttpRoutes[F])(

def server[F[_]: Trace](
routes: HttpRoutes[F],
isKernelHeader: CIString => Boolean = name => !ExcludedHeaders.contains(name),
spanName: Request[F] => String = (req: Request[F]) => req.uri.path.toString,
modifySpanOptions: Span.Options => Span.Options = identity
)(
implicit ev: MonadCancel[F, Throwable]
): HttpRoutes[F] =
Kleisli { req =>
Expand Down Expand Up @@ -71,17 +98,25 @@ object NatchezMiddleware {
new String(baos.toByteArray, "UTF-8")
}
)

routes(req).guaranteeCase {
case Canceled() => OptionT.liftF(addRequestFields *> Trace[F].put(("cancelled", TraceValue.BooleanValue(true)), Tags.error(true)))
case Errored(e) => OptionT.liftF(addRequestFields *> addErrorFields(e))
case Succeeded(fa) => OptionT.liftF {
fa.value.flatMap {
case Some(resp) => addRequestFields *> addResponseFields(resp)
case None => MonadCancel[F].unit
val kernelHeaders = req.headers.headers
.collect {
case header if isKernelHeader(header.name) => header.name -> header.value
}
.toMap
val kernel = Kernel(kernelHeaders)
OptionT(
Trace[F].span(spanName(req), modifySpanOptions(Span.Options.Defaults.withParentKernel(kernel).withSpanKind(Span.SpanKind.Server))) {
addRequestFields >> routes(req).value.guaranteeCase {
case Canceled() => Trace[F].put(("cancelled", TraceValue.BooleanValue(true)), Tags.error(true))
case Errored(e) => addErrorFields(e)
case Succeeded(fa) =>
fa.flatMap {
case Some(resp) => addResponseFields(resp)
case None => ev.unit
}
}
}
}
)
}

/**
Expand Down Expand Up @@ -113,4 +148,25 @@ object NatchezMiddleware {
}
}

val ExcludedHeaders: Set[CIString] = {
import org.http4s.headers._
import org.typelevel.ci._

val payload = Set(
`Content-Length`.name,
ci"Content-Type",
`Content-Range`.name,
ci"Trailer",
`Transfer-Encoding`.name,
)

val security = Set(
Authorization.name,
Cookie.name,
`Set-Cookie`.name,
)

payload ++ security
}

}
97 changes: 13 additions & 84 deletions modules/http4s/src/main/scala/natchez/http4s/syntax/EntryPointOps.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -6,140 +6,69 @@ package natchez.http4s.syntax

import cats.~>
import cats.data.{ Kleisli, OptionT }
import cats.data.Kleisli.applyK
import cats.effect.MonadCancel
import natchez.{ EntryPoint, Kernel, Span }
import org.http4s.HttpRoutes
import cats.effect.Resource
import org.http4s.server.websocket.WebSocketBuilder2
import org.typelevel.ci.CIString
import natchez.EntryPoint
import natchez.Span

/**
* @define excludedHeaders
* All headers except security (Authorization, Cookie, Set-Cookie)
* and payload (Content-Length, ContentType, Content-Range, Trailer, Transfer-Encoding)
* are passed to Kernel by default.
*
* @define isKernelHeader should an HTTP header be passed to Kernel or not
*
* @define spanName compute the span name from the request
*
* @define spanOptions options used in span creation
*/
trait EntryPointOps[F[_]] { outer =>

def self: EntryPoint[F]

/**
* Given an entry point and HTTP Routes in Kleisli[F, Span[F], *] return routes in F. A new span
* is created with by default the URI path as the name, either as a continuation of the incoming trace, if
* any, or as a new root.
* Given an entry point and HTTP Routes in Kleisli[F, Span[F], *] return routes in F.
* A span that is injected is a RootsSpan (smilarly to Trace.ioTraceForEntryPoint)
*
* @note $excludedHeaders
*
* @param isKernelHeader $isKernelHeader
* @param spanName $spanName
* @param spanOptions $spanOptions
*/
def liftT(
routes: HttpRoutes[Kleisli[F, Span[F], *]],
isKernelHeader: CIString => Boolean = name => !EntryPointOps.ExcludedHeaders.contains(name),
spanName: org.http4s.Request[F] => String = _.uri.path.toString,
spanOptions: Span.Options = Span.Options.Defaults,
)(implicit ev: MonadCancel[F, Throwable]): HttpRoutes[F] =
Kleisli { req =>
val kernelHeaders = req.headers.headers
.collect {
case header if isKernelHeader(header.name) => header.name -> header.value
}
.toMap

val kernel = Kernel(kernelHeaders)
val spanR = self.continueOrElseRoot(spanName(req), kernel, spanOptions)
OptionT {
spanR.use { span =>
routes.run(req.mapK(lift)).mapK(applyK(span)).map(_.mapK(applyK(span))).value
}
}
val root = Span.makeRoots(self)
OptionT(routes.run(req.mapK(Kleisli.liftK)).mapK(Kleisli.applyK(root)).map(_.mapK(Kleisli.applyK(root))).value)
}


/**
* Lift an `HttpRoutes`-yielding resource that consumes `Span`s into the bare effect. We do this
* by ignoring any tracing that happens during allocation and freeing of the `HttpRoutes`
* resource. The reasoning is that such a resource typically lives for the lifetime of the
* application and it's of little use to keep a span open that long.
*
* @note $excludedHeaders
*
* @param isKernelHeader $isKernelHeader
*/
def liftR(
routes: Resource[Kleisli[F, Span[F], *], HttpRoutes[Kleisli[F, Span[F], *]]],
isKernelHeader: CIString => Boolean = name => !EntryPointOps.ExcludedHeaders.contains(name)
)(implicit ev: MonadCancel[F, Throwable]): Resource[F, HttpRoutes[F]] =
routes.map(liftT(_, isKernelHeader)).mapK(Span.dropTracing)
routes.map(liftT).mapK(Span.dropTracing)

/**
* Given an entry point and a function from `WebSocketBuilder2` to HTTP Routes in
* Kleisli[F, Span[F], *] return a function from `WebSocketBuilder2` to routes in F. A new span
* is created with the URI path as the name, either as a continuation of the incoming trace, if
* any, or as a new root.
*
* @note $excludedHeaders
*
* @param isKernelHeader $isKernelHeader
* Kleisli[F, Span[F], *] return a function from `WebSocketBuilder2` to routes in F.
*/
def wsLiftT(
routes: WebSocketBuilder2[Kleisli[F, Span[F], *]] => HttpRoutes[Kleisli[F, Span[F], *]],
isKernelHeader: CIString => Boolean = name => !EntryPointOps.ExcludedHeaders.contains(name),
spanName: org.http4s.Request[F] => String = _.uri.path.toString,
spanOptions: Span.Options = Span.Options.Defaults
routes: WebSocketBuilder2[Kleisli[F, Span[F], *]] => HttpRoutes[Kleisli[F, Span[F], *]]
)(implicit ev: MonadCancel[F, Throwable]): WebSocketBuilder2[F] => HttpRoutes[F] = wsb =>
liftT(routes(wsb.imapK(lift)(Span.dropTracing)), isKernelHeader, spanName, spanOptions)
liftT(routes(wsb.imapK(lift)(Span.dropTracing)))

/**
* Lift a `WebSocketBuilder2 => HttpRoutes`-yielding resource that consumes `Span`s into the bare
* effect. We do this by ignoring any tracing that happens during allocation and freeing of the
* `HttpRoutes` resource. The reasoning is that such a resource typically lives for the lifetime
* of the application and it's of little use to keep a span open that long.
*
* @note $excludedHeaders
*
* @param isKernelHeader $isKernelHeader
*/
def wsLiftR(
routes: Resource[Kleisli[F, Span[F], *], WebSocketBuilder2[Kleisli[F, Span[F], *]] => HttpRoutes[Kleisli[F, Span[F], *]]],
isKernelHeader: CIString => Boolean = name => !EntryPointOps.ExcludedHeaders.contains(name),
spanName: org.http4s.Request[F] => String = _.uri.path.toString,
spanOptions: Span.Options = Span.Options.Defaults
routes: Resource[Kleisli[F, Span[F], *], WebSocketBuilder2[Kleisli[F, Span[F], *]] => HttpRoutes[Kleisli[F, Span[F], *]]]
)(implicit ev: MonadCancel[F, Throwable]): Resource[F, WebSocketBuilder2[F] => HttpRoutes[F]] =
routes.map(wsLiftT(_, isKernelHeader, spanName, spanOptions)).mapK(Span.dropTracing)
routes.map(wsLiftT).mapK(Span.dropTracing)

private val lift: F ~> Kleisli[F, Span[F], *] =
Kleisli.liftK
}

object EntryPointOps {
val ExcludedHeaders: Set[CIString] = {
import org.http4s.headers._
import org.typelevel.ci._

val payload = Set(
`Content-Length`.name,
ci"Content-Type",
`Content-Range`.name,
ci"Trailer",
`Transfer-Encoding`.name,
)

val security = Set(
Authorization.name,
Cookie.name,
`Set-Cookie`.name,
)

payload ++ security
}
}

trait ToEntryPointOps {
Expand Down
2 changes: 1 addition & 1 deletion modules/http4s/src/test/scala/natchez/http4s/NatchezMiddlewareSuite.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -97,14 +97,14 @@ class NatchezMiddlewareSuite extends InMemorySuite {

List(
(Lineage.Root, NatchezCommand.CreateRootSpan("/hello/some-name", requestKernel, Span.Options.Defaults)),
(Lineage.Root, NatchezCommand.Put(requestTags)),
(Lineage.Root, NatchezCommand.CreateSpan("call-proxy", None, Span.Options.Defaults)),
(Lineage.Root / "call-proxy", NatchezCommand.CreateSpan("http4s-client-request", None, Span.Options.Defaults)),
(Lineage.Root / "call-proxy" / "http4s-client-request", NatchezCommand.AskKernel(requestKernel)),
(Lineage.Root / "call-proxy" / "http4s-client-request", NatchezCommand.Put(clientRequestTags)),
(Lineage.Root / "call-proxy" / "http4s-client-request", NatchezCommand.Put(clientResponseTags)),
(Lineage.Root / "call-proxy", NatchezCommand.ReleaseSpan("http4s-client-request")),
(Lineage.Root, NatchezCommand.ReleaseSpan("call-proxy")),
(Lineage.Root, NatchezCommand.Put(requestTags)),
(Lineage.Root, NatchezCommand.Put(responseTags)),
(Lineage.Root, NatchezCommand.ReleaseRootSpan("/hello/some-name"))
)
Expand Down

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