From ba6111e2a4829447d9dbc6ca28e721bc7547e6b8 Mon Sep 17 00:00:00 2001
From: Seth Vargo <seth@sethvargo.com>
Date: Tue, 10 Apr 2018 10:36:46 -0400
Subject: [PATCH] Set user-agent when talking to GCE metadata

---
 client/fingerprint/env_gce.go      |  2 ++
 client/fingerprint/env_gce_test.go |  9 +++++++++
 helper/useragent/useragent.go      | 29 +++++++++++++++++++++++++++++
 helper/useragent/useragent_test.go | 18 ++++++++++++++++++
 4 files changed, 58 insertions(+)
 create mode 100644 helper/useragent/useragent.go
 create mode 100644 helper/useragent/useragent_test.go

diff --git a/client/fingerprint/env_gce.go b/client/fingerprint/env_gce.go
index 280914f3d..e404e2415 100644
--- a/client/fingerprint/env_gce.go
+++ b/client/fingerprint/env_gce.go
@@ -15,6 +15,7 @@ import (
 
 	"github.com/hashicorp/go-cleanhttp"
 	cstructs "github.com/hashicorp/nomad/client/structs"
+	"github.com/hashicorp/nomad/helper/useragent"
 	"github.com/hashicorp/nomad/nomad/structs"
 )
 
@@ -97,6 +98,7 @@ func (f *EnvGCEFingerprint) Get(attribute string, recursive bool) (string, error
 		URL:    parsedUrl,
 		Header: http.Header{
 			"Metadata-Flavor": []string{"Google"},
+			"User-Agent":      []string{useragent.String()},
 		},
 	}
 
diff --git a/client/fingerprint/env_gce_test.go b/client/fingerprint/env_gce_test.go
index 14837dca8..9d1a2c4bc 100644
--- a/client/fingerprint/env_gce_test.go
+++ b/client/fingerprint/env_gce_test.go
@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"os"
+	"strings"
 	"testing"
 
 	"github.com/hashicorp/nomad/client/config"
@@ -66,6 +67,14 @@ func testFingerprint_GCE(t *testing.T, withExternalIp bool) {
 			t.Fatalf("Expected Metadata-Flavor Google, saw %s", value[0])
 		}
 
+		uavalue, ok := r.Header["User-Agent"]
+		if !ok {
+			t.Fatal("User-Agent not present in HTTP request header")
+		}
+		if !strings.Contains(uavalue[0], "Nomad/") {
+			t.Fatalf("Expected User-Agent to contain Nomad/, got %s", uavalue[0])
+		}
+
 		found := false
 		for _, e := range routes.Endpoints {
 			if r.RequestURI == e.Uri {
diff --git a/helper/useragent/useragent.go b/helper/useragent/useragent.go
new file mode 100644
index 000000000..149ae5366
--- /dev/null
+++ b/helper/useragent/useragent.go
@@ -0,0 +1,29 @@
+package useragent
+
+import (
+	"fmt"
+	"runtime"
+
+	"github.com/hashicorp/nomad/version"
+)
+
+var (
+	// projectURL is the project URL.
+	projectURL = "https://www.nomadproject.io/"
+
+	// rt is the runtime - variable for tests.
+	rt = runtime.Version()
+
+	// versionFunc is the func that returns the current version. This is a
+	// function to take into account the different build processes and distinguish
+	// between enterprise and oss builds.
+	versionFunc = func() string {
+		return version.GetVersion().VersionNumber()
+	}
+)
+
+// String returns the consistent user-agent string for Nomad.
+func String() string {
+	return fmt.Sprintf("Nomad/%s (+%s; %s)",
+		versionFunc(), projectURL, rt)
+}
diff --git a/helper/useragent/useragent_test.go b/helper/useragent/useragent_test.go
new file mode 100644
index 000000000..7a83a0873
--- /dev/null
+++ b/helper/useragent/useragent_test.go
@@ -0,0 +1,18 @@
+package useragent
+
+import (
+	"testing"
+)
+
+func TestUserAgent(t *testing.T) {
+	projectURL = "https://nomad-test.com"
+	rt = "go5.0"
+	versionFunc = func() string { return "1.2.3" }
+
+	act := String()
+
+	exp := "Nomad/1.2.3 (+https://nomad-test.com; go5.0)"
+	if exp != act {
+		t.Errorf("expected %q to be %q", act, exp)
+	}
+}