Added version round tripper

internal/pkg/fleetapi/client/client.go

@@ -43,8 +43,9 @@ type Sender interface {
 const defaultFleetApiVersion = "2023-06-01"
 
 var baseRoundTrippers = func(rt http.RoundTripper) (http.RoundTripper, error) {
-	rt = NewFleetUserAgentRoundTripper(rt, release.Version())
-
+	ver := release.Version()
+	rt = NewFleetUserAgentRoundTripper(rt, ver)
+	rt = NewElasticAgentVersionRoundTripper(rt, ver)
 	rt = NewElasticApiVersionRoundTripper(rt, defaultFleetApiVersion)
 
 	return rt, nil

internal/pkg/fleetapi/client/client_test.go

@@ -111,6 +111,36 @@ func TestHTTPClient(t *testing.T) {
 		},
 	))
 
+	t.Run("Elastic Agent Version header", withServer(
+		func(t *testing.T) *http.ServeMux {
+			msg := `{ message: "hello" }`
+			mux := http.NewServeMux()
+			mux.HandleFunc("/echo-hello", func(w http.ResponseWriter, r *http.Request) {
+				w.WriteHeader(http.StatusOK)
+				fmt.Fprint(w, msg)
+				require.Equal(t, r.Header.Get("Elastic-Agent-Version"), "v8.0.0")
+			})
+			return mux
+		}, func(t *testing.T, host string) {
+			cfg := config.MustNewConfigFrom(map[string]interface{}{
+				"host": host,
+			})
+
+			client, err := remote.NewWithRawConfig(nil, cfg, func(wrapped http.RoundTripper) (http.RoundTripper, error) {
+				return NewElasticAgentVersionRoundTripper(wrapped, "8.0.0"), nil
+			})
+
+			require.NoError(t, err)
+			resp, err := client.Send(ctx, "GET", "/echo-hello", nil, nil, nil)
+			require.NoError(t, err)
+
+			body, err := io.ReadAll(resp.Body)
+			require.NoError(t, err)
+			defer resp.Body.Close()
+			assert.Equal(t, `{ message: "hello" }`, string(body))
+		},
+	))
+
 	t.Run("Fleet endpoint is not responding", func(t *testing.T) {
 		cfg := config.MustNewConfigFrom(map[string]interface{}{
 			"host": "127.0.0.0:7278",

internal/pkg/fleetapi/client/round_trippers.go

@@ -7,6 +7,7 @@ package client
 import (
 	"errors"
 	"net/http"
+	"strings"
 
 	"github.com/elastic/elastic-agent/internal/pkg/remote"
 )
@@ -88,3 +89,26 @@ func (r *ElasticApiVersionRoundTripper) RoundTrip(req *http.Request) (*http.Resp
 func NewElasticApiVersionRoundTripper(inner http.RoundTripper, elasticApiVersion string) http.RoundTripper {
 	return &ElasticApiVersionRoundTripper{elasticApiVersion: elasticApiVersion, rt: inner}
 }
+
+// ElasticAgentVersionRoundTripper adds an Elastic-Agent-Version header on every request.
+type ElasticAgentVersionRoundTripper struct {
+	rt      http.RoundTripper
+	version string
+}
+
+const elasticAgentVersionHeaderKey = "Elastic-Agent-Version"
+
+// RoundTrip adds an Elastic-Agent-Version header on every request.
+func (r *ElasticAgentVersionRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	req.Header.Set(elasticAgentVersionHeaderKey, r.version)
+
+	return r.rt.RoundTrip(req)
+}
+
+// NewElasticAgentVersionRoundTripper returns a RoundTripper that sets Elastic-Agent-Version on each request.
+func NewElasticAgentVersionRoundTripper(inner http.RoundTripper, version string) http.RoundTripper {
+	if !strings.HasPrefix(version, "v") {
+		version = "v" + version
+	}
+	return &ElasticAgentVersionRoundTripper{rt: inner, version: version}
+}