Merge pull request #146 from slashmo/feature/http-headers-extractor-multiple-values

Join multiple header values in HTTPHeadersExtractor

Author: slashmo

Sources/NIOInstrumentation/HTTPHeadersCarrier.swift

@@ -14,14 +14,24 @@
 import Instrumentation
 import NIOHTTP1
 
+/// Extracts header values from `NIOHTTP1.HTTPHeaders`.
+///
+/// If multiple entries exist for a given key, their values will be joined according to
+/// [HTTP RFC 7230: Field Order](https://httpwg.org/specs/rfc7230.html#rfc.section.3.2.2), returning a comma-separated list
+/// of the values.
 public struct HTTPHeadersExtractor: ExtractorProtocol {
     public init() {}
 
     public func extract(key: String, from headers: HTTPHeaders) -> String? {
-        return headers.first(name: key)
+        return headers
+            .lazy
+            .filter { $0.name == key }
+            .map { $0.value }
+            .joined(separator: ",")
     }
 }
 
+/// Injects values into `NIOHTTP1.HTTPHeaders`.
 public struct HTTPHeadersInjector: InjectorProtocol {
     public init() {}
 

Tests/LinuxMain.swift

@@ -37,6 +37,7 @@ class LinuxMainRunnerImpl: LinuxMainRunner {
        XCTMain([
              testCase(BaggageContextInboundHTTPHandlerTests.allTests),
              testCase(BaggageContextOutboundHTTPHandlerTests.allTests),
+             testCase(HTTPHeadersCarrierTests.allTests),
              testCase(InstrumentTests.allTests),
              testCase(InstrumentationSystemTests.allTests),
              testCase(SpanAttributeSemanticsTests.allTests),

Tests/NIOInstrumentationTests/HTTPHeadersCarrierTests+XCTest.swift

@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift Distributed Tracing open source project
+//
+// Copyright (c) 2020 Moritz Lang and the Swift Tracing project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+//
+// HTTPHeadersCarrierTests+XCTest.swift
+//
+import XCTest
+///
+/// NOTE: This file was generated by generate_linux_tests.rb
+///
+/// Do NOT edit this file directly as it will be regenerated automatically when needed.
+///
+
+extension HTTPHeadersCarrierTests {
+
+   @available(*, deprecated, message: "not actually deprecated. Just deprecated to allow deprecated tests (which test deprecated functionality) without warnings")
+   static var allTests : [(String, (HTTPHeadersCarrierTests) -> () throws -> Void)] {
+      return [
+                ("testExtractSingleHeader", testExtractSingleHeader),
+                ("testExtractMultipleHeadersOfSameName", testExtractMultipleHeadersOfSameName),
+           ]
+   }
+}
+

Tests/NIOInstrumentationTests/HTTPHeadersCarrierTests.swift

@@ -0,0 +1,57 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift Distributed Tracing open source project
+//
+// Copyright (c) 2020 Moritz Lang and the Swift Tracing project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import NIOHTTP1
+import NIOInstrumentation
+import XCTest
+
+final class HTTPHeadersCarrierTests: XCTestCase {
+    func testExtractSingleHeader() {
+        let headers: HTTPHeaders = [
+            "tracestate": "vendorname1=opaqueValue1,vendorname2=opaqueValue2",
+            "traceparent": "00-0af7651916cd43dd8448eb211c80319c-b9c7c989f97918e1-01",
+        ]
+
+        let extractor = HTTPHeadersExtractor()
+
+        XCTAssertEqual(
+            extractor.extract(key: "tracestate", from: headers),
+            "vendorname1=opaqueValue1,vendorname2=opaqueValue2"
+        )
+
+        XCTAssertEqual(
+            extractor.extract(key: "traceparent", from: headers),
+            "00-0af7651916cd43dd8448eb211c80319c-b9c7c989f97918e1-01"
+        )
+    }
+
+    func testExtractMultipleHeadersOfSameName() {
+        let headers: HTTPHeaders = [
+            "tracestate": "vendorname1=opaqueValue1",
+            "traceparent": "00-0af7651916cd43dd8448eb211c80319c-b9c7c989f97918e1-01",
+            "tracestate": "vendorname2=opaqueValue2",
+        ]
+
+        let extractor = HTTPHeadersExtractor()
+
+        XCTAssertEqual(
+            extractor.extract(key: "tracestate", from: headers),
+            "vendorname1=opaqueValue1,vendorname2=opaqueValue2"
+        )
+
+        XCTAssertEqual(
+            extractor.extract(key: "traceparent", from: headers),
+            "00-0af7651916cd43dd8448eb211c80319c-b9c7c989f97918e1-01"
+        )
+    }
+}