pkg/trace/api: enable Windows pipe support (#6615)

Windows pipes are now supported by means of:

* `DD_APM_WINDOWS_PIPE_NAME` defines the pipe name to be used.
* `DD_APM_WINDOWS_PIPE_BUFFER_SIZE` defines the input buffer size
  (defaults to 1MB).
* `DD_APM_WINDOWS_PIPE_SECURITY_DESCRIPTOR` allows setting the security ID. Defaults to `D:AI(A;;GA;;;WD)` (grants access to everyone)

pkg/config/apm.go

@@ -43,6 +43,8 @@ func setupAPM(config Config) {
 	}
 
 	config.BindEnvAndSetDefault("apm_config.receiver_port", 8126, "DD_APM_RECEIVER_PORT", "DD_RECEIVER_PORT")
+	config.BindEnvAndSetDefault("apm_config.windows_pipe_buffer_size", 1_000_000, "DD_APM_WINDOWS_PIPE_BUFFER_SIZE")                          //nolint:errcheck
+	config.BindEnvAndSetDefault("apm_config.windows_pipe_security_descriptor", "D:AI(A;;GA;;;WD)", "DD_APM_WINDOWS_PIPE_SECURITY_DESCRIPTOR") //nolint:errcheck
 
 	config.BindEnv("apm_config.receiver_timeout", "DD_APM_RECEIVER_TIMEOUT")                             //nolint:errcheck
 	config.BindEnv("apm_config.max_payload_size", "DD_APM_MAX_PAYLOAD_SIZE")                             //nolint:errcheck
@@ -63,6 +65,7 @@ func setupAPM(config Config) {
 	config.BindEnv("apm_config.analyzed_spans", "DD_APM_ANALYZED_SPANS")                                 //nolint:errcheck
 	config.BindEnv("apm_config.ignore_resources", "DD_APM_IGNORE_RESOURCES", "DD_IGNORE_RESOURCE")       //nolint:errcheck
 	config.BindEnv("apm_config.receiver_socket", "DD_APM_RECEIVER_SOCKET")                               //nolint:errcheck
+	config.BindEnv("apm_config.windows_pipe_name", "DD_APM_WINDOWS_PIPE_NAME")                           //nolint:errcheck
 
 	config.SetEnvKeyTransformer("apm_config.ignore_resources", func(in string) interface{} {
 		r, err := splitCSVString(in, ',')

pkg/trace/api/api.go

@@ -121,6 +121,7 @@ func (r *HTTPReceiver) Start() {
 	go func() {
 		defer watchdog.LogOnPanic()
 		r.server.Serve(ln)
+		ln.Close()
 	}()
 	log.Infof("Listening for traces at http://%s", addr)
 
@@ -132,10 +133,27 @@ func (r *HTTPReceiver) Start() {
 		go func() {
 			defer watchdog.LogOnPanic()
 			r.server.Serve(ln)
+			ln.Close()
 		}()
 		log.Infof("Listening for traces at unix://%s", path)
 	}
 
+	if path := mainconfig.Datadog.GetString("apm_config.windows_pipe_name"); path != "" {
+		pipepath := `\\.\pipe\` + path
+		bufferSize := mainconfig.Datadog.GetInt("apm_config.windows_pipe_buffer_size")
+		secdec := mainconfig.Datadog.GetString("apm_config.windows_pipe_security_descriptor")
+		ln, err := listenPipe(pipepath, secdec, bufferSize)
+		if err != nil {
+			killProcess("Error creating %q named pipe: %v", pipepath, err)
+		}
+		go func() {
+			defer watchdog.LogOnPanic()
+			r.server.Serve(ln)
+			ln.Close()
+		}()
+		log.Infof("Listening for traces on Windowes pipe %q. Security descriptor is %q", pipepath, secdec)
+	}
+
 	go r.RateLimiter.Run()
 
 	go func() {

pkg/trace/api/pipe.go

@@ -0,0 +1,21 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-2020 Datadog, Inc.
+
+// +build windows
+
+package api
+
+import (
+	"net"
+
+	"github.com/Microsoft/go-winio"
+)
+
+func listenPipe(path string, secdec string, bufferSize int) (net.Listener, error) {
+	return winio.ListenPipe(path, &winio.PipeConfig{
+		SecurityDescriptor: secdec,
+		InputBufferSize:    int32(bufferSize),
+	})
+}

pkg/trace/api/pipe_off.go

@@ -0,0 +1,17 @@
+// Unless explicitly stated otherwise all files in this repository are licensed
+// under the Apache License Version 2.0.
+// This product includes software developed at Datadog (https://www.datadoghq.com/).
+// Copyright 2016-2020 Datadog, Inc.
+
+// +build !windows
+
+package api
+
+import (
+	"errors"
+	"net"
+)
+
+func listenPipe(_, _ string, _ int) (net.Listener, error) {
+	return nil, errors.New("Windows named pipes are only supported on Windows operating systems")
+}

releasenotes/notes/apm-windows-pipe-c8de92ce85fd930b.yaml

@@ -0,0 +1,12 @@
+# Each section from every releasenote are combined when the
+# CHANGELOG.rst is rendered. So the text needs to be worded so that
+# it does not depend on any information only available in another
+# section. This may mean repeating some details, but each section
+# must be readable independently of the other.
+#
+# Each section note must be formatted as reStructuredText.
+---
+features:
+  - |
+    APM: Added support for Windows pipes. To enable it, set the pipe path using
+    DD_APM_WINDOWS_PIPE_NAME. For more details check https://github.com/DataDog/datadog-agent/pull/6615