Standardize http.Client creation with User-Agent

backend/remote-state/gcs/backend.go

@@ -13,7 +13,7 @@ import (
 	"github.com/hashicorp/terraform/backend"
 	"github.com/hashicorp/terraform/helper/pathorcontents"
 	"github.com/hashicorp/terraform/helper/schema"
-	"github.com/hashicorp/terraform/terraform"
+	"github.com/hashicorp/terraform/httpclient"
 	"golang.org/x/oauth2/jwt"
 	"google.golang.org/api/option"
 )
@@ -156,7 +156,7 @@ func (b *gcsBackend) configure(ctx context.Context) error {
 		opts = append(opts, option.WithScopes(storage.ScopeReadWrite))
 	}
 
-	opts = append(opts, option.WithUserAgent(terraform.UserAgentString()))
+	opts = append(opts, option.WithUserAgent(httpclient.UserAgentString()))
 	client, err := storage.NewClient(b.storageContext, opts...)
 	if err != nil {
 		return fmt.Errorf("storage.NewClient() failed: %v", err)

httpclient/client.go

@@ -0,0 +1,18 @@
+package httpclient
+
+import (
+	"net/http"
+
+	cleanhttp "github.com/hashicorp/go-cleanhttp"
+)
+
+// New returns the DefaultPooledClient from the cleanhttp
+// package that will also send a Terraform User-Agent string.
+func New() *http.Client {
+	cli := cleanhttp.DefaultPooledClient()
+	cli.Transport = &userAgentRoundTripper{
+		userAgent: UserAgentString(),
+		inner:     cli.Transport,
+	}
+	return cli
+}

httpclient/client_test.go

@@ -0,0 +1,77 @@
+package httpclient
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/hashicorp/terraform/version"
+)
+
+func TestUserAgent(t *testing.T) {
+	var actualUserAgent string
+	ts := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+		actualUserAgent = req.UserAgent()
+	}))
+	defer ts.Close()
+
+	tsURL, err := url.Parse(ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for i, c := range []struct {
+		expected string
+		request  func(c *http.Client) error
+	}{
+		{
+			fmt.Sprintf("Terraform/%s", version.Version),
+			func(c *http.Client) error {
+				_, err := c.Get(ts.URL)
+				return err
+			},
+		},
+		{
+			"foo/1",
+			func(c *http.Client) error {
+				req := &http.Request{
+					Method: "GET",
+					URL:    tsURL,
+					Header: http.Header{
+						"User-Agent": []string{"foo/1"},
+					},
+				}
+				_, err := c.Do(req)
+				return err
+			},
+		},
+		{
+			"",
+			func(c *http.Client) error {
+				req := &http.Request{
+					Method: "GET",
+					URL:    tsURL,
+					Header: http.Header{
+						"User-Agent": []string{""},
+					},
+				}
+				_, err := c.Do(req)
+				return err
+			},
+		},
+	} {
+		t.Run(fmt.Sprintf("%d %s", i, c.expected), func(t *testing.T) {
+			actualUserAgent = ""
+			cli := New()
+			err := c.request(cli)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if actualUserAgent != c.expected {
+				t.Fatalf("actual User-Agent '%s' is not '%s'", actualUserAgent, c.expected)
+			}
+		})
+	}
+}

httpclient/useragent.go

@@ -0,0 +1,26 @@
+package httpclient
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/hashicorp/terraform/version"
+)
+
+const userAgentFormat = "Terraform/%s"
+
+func UserAgentString() string {
+	return fmt.Sprintf(userAgentFormat, version.Version)
+}
+
+type userAgentRoundTripper struct {
+	inner     http.RoundTripper
+	userAgent string
+}
+
+func (rt *userAgentRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	if _, ok := req.Header["User-Agent"]; !ok {
+		req.Header.Set("User-Agent", rt.userAgent)
+	}
+	return rt.inner.RoundTrip(req)
+}

plugin/discovery/get.go

@@ -15,9 +15,9 @@ import (
 
 	"golang.org/x/net/html"
 
-	cleanhttp "github.com/hashicorp/go-cleanhttp"
 	getter "github.com/hashicorp/go-getter"
 	multierror "github.com/hashicorp/go-multierror"
+	"github.com/hashicorp/terraform/httpclient"
 	"github.com/mitchellh/cli"
 )
 
@@ -33,7 +33,19 @@ const protocolVersionHeader = "x-terraform-protocol-version"
 
 var releaseHost = "https://releases.hashicorp.com"
 
-var httpClient = cleanhttp.DefaultPooledClient()
+var httpClient *http.Client
+
+func init() {
+	httpClient = httpclient.New()
+
+	httpGetter := &getter.HttpGetter{
+		Client: httpClient,
+		Netrc:  true,
+	}
+
+	getter.Getters["http"] = httpGetter
+	getter.Getters["https"] = httpGetter
+}
 
 // An Installer maintains a local cache of plugins by downloading plugins
 // from an online repository.

registry/client.go

@@ -11,7 +11,7 @@ import (
 	"strings"
 	"time"
 
-	cleanhttp "github.com/hashicorp/go-cleanhttp"
+	"github.com/hashicorp/terraform/httpclient"
 	"github.com/hashicorp/terraform/registry/regsrc"
 	"github.com/hashicorp/terraform/registry/response"
 	"github.com/hashicorp/terraform/svchost"
@@ -51,7 +51,7 @@ func NewClient(services *disco.Disco, creds auth.CredentialsSource, client *http
 	services.SetCredentialsSource(creds)
 
 	if client == nil {
-		client = cleanhttp.DefaultPooledClient()
+		client = httpclient.New()
 		client.Timeout = requestTimeout
 	}
 

state/remote/gcs.go

@@ -8,18 +8,16 @@ import (
 	"log"
 	"net/http"
 	"os"
-	"runtime"
 	"strings"
 
 	"github.com/hashicorp/terraform/helper/pathorcontents"
+	"github.com/hashicorp/terraform/httpclient"
 	"golang.org/x/net/context"
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/google"
 	"golang.org/x/oauth2/jwt"
 	"google.golang.org/api/googleapi"
 	"google.golang.org/api/storage/v1"
-
-	version "github.com/hashicorp/terraform/version"
 )
 
 // accountFile represents the structure of the credentials JSON
@@ -100,16 +98,13 @@ func gcsFactory(conf map[string]string) (Client, error) {
 			return nil, err
 		}
 	}
-	versionString := version.Version
-	userAgent := fmt.Sprintf(
-		"(%s %s) Terraform/%s", runtime.GOOS, runtime.GOARCH, versionString)
 
 	log.Printf("[INFO] Instantiating Google Storage Client...")
 	clientStorage, err := storage.New(client)
 	if err != nil {
 		return nil, err
 	}
-	clientStorage.UserAgent = userAgent
+	clientStorage.UserAgent = httpclient.UserAgentString()
 
 	return &GCSClient{
 		clientStorage: clientStorage,

svchost/disco/disco.go

@@ -8,7 +8,6 @@ package disco
 import (
 	"encoding/json"
 	"errors"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
@@ -20,7 +19,6 @@ import (
 	cleanhttp "github.com/hashicorp/go-cleanhttp"
 	"github.com/hashicorp/terraform/svchost"
 	"github.com/hashicorp/terraform/svchost/auth"
-	"github.com/hashicorp/terraform/version"
 )
 
 const (
@@ -30,7 +28,6 @@ const (
 	maxDiscoDocBytes = 1 * 1024 * 1024  // 1MB - to prevent abusive services from using loads of our memory
 )
 
-var userAgent = fmt.Sprintf("Terraform/%s (service discovery)", version.String())
 var httpTransport = cleanhttp.DefaultPooledTransport() // overridden during tests, to skip TLS verification
 
 // Disco is the main type in this package, which allows discovery on given
@@ -142,13 +139,9 @@ func (d *Disco) discover(host svchost.Hostname) Host {
 		},
 	}
 
-	var header = http.Header{}
-	header.Set("User-Agent", userAgent)
-
 	req := &http.Request{
 		Method: "GET",
 		URL:    discoURL,
-		Header: header,
 	}
 
 	if d.credsSrc != nil {

terraform/user_agent.go

@@ -1,16 +1,13 @@
 package terraform
 
 import (
-	"fmt"
-	"runtime"
-
-	"github.com/hashicorp/terraform/version"
+	"github.com/hashicorp/terraform/httpclient"
 )
 
-// The standard Terraform User-Agent format
-const UserAgent = "Terraform %s (%s)"
-
 // Generate a UserAgent string
+//
+// Deprecated: Use httpclient.UserAgentString if you are setting your
+// own User-Agent header.
 func UserAgentString() string {
-	return fmt.Sprintf(UserAgent, version.String(), runtime.Version())
+	return httpclient.UserAgentString()
 }