From 2c85a72737ae4ff70d91b7d08038d73a3fbe899b Mon Sep 17 00:00:00 2001
From: Rajat Vig <rvig@etsy.com>
Date: Thu, 16 Dec 2021 14:12:32 +0000
Subject: [PATCH] Add back copyTraceHeaders() as OpenTelemetry does not default
 propagate

---
 cmd/podinfo/main.go         |  2 +-
 pkg/api/echo.go             | 22 +++++++++++++++++
 pkg/api/mock.go             | 48 ++++++++++++++++++-------------------
 pkg/signals/signal_posix.go |  1 +
 4 files changed, 48 insertions(+), 25 deletions(-)

diff --git a/cmd/podinfo/main.go b/cmd/podinfo/main.go
index 987d54f..b7af51f 100644
--- a/cmd/podinfo/main.go
+++ b/cmd/podinfo/main.go
@@ -53,7 +53,7 @@ func main() {
 	fs.Int("stress-cpu", 0, "number of CPU cores with 100 load")
 	fs.Int("stress-memory", 0, "MB of data to load into memory")
 	fs.String("cache-server", "", "Redis address in the format <host>:<port>")
-	fs.String("otel-service-name", "podinfo", "Redis address in the format <host>:<port>")
+	fs.String("otel-service-name", "podinfo", "service name for reporting to open telemetry address")
 
 	versionFlag := fs.BoolP("version", "v", false, "get version number")
 
diff --git a/pkg/api/echo.go b/pkg/api/echo.go
index 8b82444..3f2ad05 100644
--- a/pkg/api/echo.go
+++ b/pkg/api/echo.go
@@ -55,6 +55,9 @@ func (s *Server) echoHandler(w http.ResponseWriter, r *http.Request) {
 					return
 				}
 
+				// forward headers
+				copyTracingHeaders(r, backendReq)
+
 				backendReq.Header.Set("X-API-Version", version.VERSION)
 				backendReq.Header.Set("X-API-Revision", version.REVISION)
 
@@ -104,3 +107,22 @@ func (s *Server) echoHandler(w http.ResponseWriter, r *http.Request) {
 		w.Write(body)
 	}
 }
+
+func copyTracingHeaders(from *http.Request, to *http.Request) {
+	headers := []string{
+		"x-request-id",
+		"x-b3-traceid",
+		"x-b3-spanid",
+		"x-b3-parentspanid",
+		"x-b3-sampled",
+		"x-b3-flags",
+		"x-ot-span-context",
+	}
+
+	for i := range headers {
+		headerValue := from.Header.Get(headers[i])
+		if len(headerValue) > 0 {
+			to.Header.Set(headers[i], headerValue)
+		}
+	}
+}
diff --git a/pkg/api/mock.go b/pkg/api/mock.go
index 79752fa..20f9d2d 100644
--- a/pkg/api/mock.go
+++ b/pkg/api/mock.go
@@ -1,34 +1,34 @@
 package api
 
 import (
-  "go.opentelemetry.io/otel/trace"
-  "time"
+	"go.opentelemetry.io/otel/trace"
+	"time"
 
-  "github.com/gorilla/mux"
-  "go.uber.org/zap"
+	"github.com/gorilla/mux"
+	"go.uber.org/zap"
 )
 
 func NewMockServer() *Server {
-  config := &Config{
-    Port:                      "9898",
-    HttpServerShutdownTimeout: 5 * time.Second,
-    HttpServerTimeout:         30 * time.Second,
-    BackendURL:                []string{},
-    ConfigPath:                "/config",
-    DataPath:                  "/data",
-    HttpClientTimeout:         30 * time.Second,
-    UIColor:                   "blue",
-    UIPath:                    ".ui",
-    UIMessage:                 "Greetings",
-    Hostname:                  "localhost",
-  }
+	config := &Config{
+		Port:                      "9898",
+		HttpServerShutdownTimeout: 5 * time.Second,
+		HttpServerTimeout:         30 * time.Second,
+		BackendURL:                []string{},
+		ConfigPath:                "/config",
+		DataPath:                  "/data",
+		HttpClientTimeout:         30 * time.Second,
+		UIColor:                   "blue",
+		UIPath:                    ".ui",
+		UIMessage:                 "Greetings",
+		Hostname:                  "localhost",
+	}
 
-  logger, _ := zap.NewDevelopment()
+	logger, _ := zap.NewDevelopment()
 
-  return &Server{
-    router: mux.NewRouter(),
-    logger: logger,
-    config: config,
-    tracer: trace.NewNoopTracerProvider().Tracer("mock"),
-  }
+	return &Server{
+		router: mux.NewRouter(),
+		logger: logger,
+		config: config,
+		tracer: trace.NewNoopTracerProvider().Tracer("mock"),
+	}
 }
diff --git a/pkg/signals/signal_posix.go b/pkg/signals/signal_posix.go
index 808c448..56184b9 100644
--- a/pkg/signals/signal_posix.go
+++ b/pkg/signals/signal_posix.go
@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 package signals