[Client] Incorporate metaheader into the client, use version from transport (#387) (#388)

* Incorporate metaheader into the client, use version from transport

Author: Anaethelion

elasticsearch.go

@@ -35,6 +35,7 @@ import (
 	"github.com/elastic/go-elasticsearch/v8/internal/version"
 
 	"github.com/elastic/elastic-transport-go/v8/elastictransport"
+	tpversion "github.com/elastic/elastic-transport-go/v8/elastictransport/version"
 )
 
 const (
@@ -43,12 +44,17 @@ const (
 	// Version returns the package version as a string.
 	Version        = version.Client
 	unknownProduct = "the client noticed that the server is not Elasticsearch and we do not support this unknown product"
+
+	// HeaderClientMeta Key for the HTTP Header related to telemetry data sent with
+	// each request to Elasticsearch.
+	HeaderClientMeta = "x-elastic-client-meta"
 )
 
 var (
 	esCompatHeader = "ELASTIC_CLIENT_APIVERSIONING"
 	userAgent      string
 	reGoVersion    = regexp.MustCompile(`go(\d+\.\d+\..+)`)
+	reMetaVersion  = regexp.MustCompile("([0-9.]+)(.*)")
 )
 
 func init() {
@@ -105,6 +111,7 @@ type Config struct {
 type Client struct {
 	*esapi.API          // Embeds the API methods
 	Transport           elastictransport.Interface
+	metaHeader          string
 	compatibilityHeader bool
 
 	disableMetaHeader   bool
@@ -216,6 +223,7 @@ func NewClient(cfg Config) (*Client, error) {
 	client := &Client{
 		Transport:           tp,
 		disableMetaHeader:   cfg.DisableMetaHeader,
+		metaHeader:          initMetaHeader(tp),
 		compatibilityHeader: cfg.EnableCompatibilityMode || compatibilityHeader,
 	}
 	client.API = esapi.New(client)
@@ -239,9 +247,9 @@ func (c *Client) Perform(req *http.Request) (*http.Response, error) {
 	if !c.disableMetaHeader {
 		existingMetaHeader := req.Header.Get(HeaderClientMeta)
 		if existingMetaHeader != "" {
-			req.Header.Set(HeaderClientMeta, strings.Join([]string{metaHeader, existingMetaHeader}, ","))
+			req.Header.Set(HeaderClientMeta, strings.Join([]string{c.metaHeader, existingMetaHeader}, ","))
 		} else {
-			req.Header.Add(HeaderClientMeta, metaHeader)
+			req.Header.Add(HeaderClientMeta, c.metaHeader)
 		}
 	} else {
 		req.Header.Del(HeaderClientMeta)
@@ -392,3 +400,61 @@ func initUserAgent() string {
 
 	return b.String()
 }
+
+func initMetaHeader(transport interface{}) string {
+	var b strings.Builder
+	var strippedGoVersion string
+	var strippedEsVersion string
+	var strippedTransportVersion string
+
+	strippedEsVersion = buildStrippedVersion(Version)
+	strippedGoVersion = buildStrippedVersion(runtime.Version())
+
+	if _, ok := transport.(*elastictransport.Client); ok {
+		strippedTransportVersion = buildStrippedVersion(tpversion.Transport)
+	} else {
+		strippedTransportVersion = strippedEsVersion
+	}
+
+	var duos = [][]string{
+		{
+			"es",
+			strippedEsVersion,
+		},
+		{
+			"go",
+			strippedGoVersion,
+		},
+		{
+			"t",
+			strippedTransportVersion,
+		},
+		{
+			"hc",
+			strippedGoVersion,
+		},
+	}
+
+	var arr []string
+	for _, duo := range duos {
+		arr = append(arr, strings.Join(duo, "="))
+	}
+	b.WriteString(strings.Join(arr, ","))
+
+	return b.String()
+}
+
+func buildStrippedVersion(version string) string {
+	v := reMetaVersion.FindStringSubmatch(version)
+
+	if len(v) == 3 && !strings.Contains(version, "devel") {
+		switch {
+		case v[2] != "":
+			return v[1] + "p"
+		default:
+			return v[1]
+		}
+	}
+
+	return "0.0p"
+}

elasticsearch_internal_test.go

@@ -39,6 +39,7 @@ import (
 	"github.com/elastic/elastic-transport-go/v8/elastictransport"
 )
 
+var metaHeaderReValidation = regexp.MustCompile(`^[a-z]{1,}=[a-z0-9\.\-]{1,}(?:,[a-z]{1,}=[a-z0-9\.\-]+)*$`)
 var called bool
 
 type mockTransp struct {
@@ -650,3 +651,90 @@ func TestCompatibilityHeader(t *testing.T) {
 		})
 	}
 }
+
+func TestBuildStrippedVersion(t *testing.T) {
+	type args struct {
+		version string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "Standard Go version",
+			args: args{version: "go1.16"},
+			want: "1.16",
+		},
+		{
+			name: "Rc Go version",
+			args: args{
+				version: "go1.16rc1",
+			},
+			want: "1.16p",
+		},
+		{
+			name: "Beta Go version (go1.16beta1 example)",
+			args: args{
+				version: "devel +2ff33f5e44 Thu Dec 17 16:03:19 2020 +0000",
+			},
+			want: "0.0p",
+		},
+		{
+			name: "Random mostly good Go version",
+			args: args{
+				version: "1.16",
+			},
+			want: "1.16",
+		},
+		{
+			name: "Client package version",
+			args: args{
+				version: "8.0.0",
+			},
+			want: "8.0.0",
+		},
+		{
+			name: "Client pre release version",
+			args: args{
+				version: "8.0.0-SNAPSHOT",
+			},
+			want: "8.0.0p",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := buildStrippedVersion(tt.args.version); got != tt.want {
+				t.Errorf("buildStrippedVersion() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestMetaHeader(t *testing.T) {
+	t.Run("MetaHeader with elastictransport", func(t *testing.T) {
+		tp, _ := elastictransport.New(elastictransport.Config{
+			URLs: []*url.URL{{Scheme: "http", Host: "foo"}},
+			Transport: &mockTransp{
+				RoundTripFunc: func(request *http.Request) (*http.Response, error) {
+					h := request.Header.Get(HeaderClientMeta)
+					if !metaHeaderReValidation.MatchString(h) {
+						t.Errorf("expected client metaheader to validate regexp, got: %s", h)
+					}
+
+					return &http.Response{
+						Header:     http.Header{"X-Elastic-Product": []string{"Elasticsearch"}},
+						StatusCode: http.StatusOK,
+						Status:     "OK",
+						Body:       ioutil.NopCloser(strings.NewReader("")),
+					}, nil
+				},
+			},
+		})
+
+		c, _ := NewDefaultClient()
+		c.Transport = tp
+
+		_, _ = c.Info()
+	})
+}