Add OpAMP-Instance-UID request header

This implements the new "OpAMP-Instance-UID" request header defined by the spec: open-telemetry/opamp-spec#270

Author: tigrannajaryan

client/clientimpl_test.go

@@ -105,7 +105,9 @@ func genNewInstanceUid(t *testing.T) types.InstanceUid {
 
 func prepareSettings(t *testing.T, settings *types.StartSettings, c OpAMPClient) {
 	// Autogenerate instance id.
-	settings.InstanceUid = genNewInstanceUid(t)
+	if settings.InstanceUid == [16]byte{} {
+		settings.InstanceUid = genNewInstanceUid(t)
+	}
 
 	// Make sure correct URL scheme is used, based on the type of the OpAMP client.
 	u, err := url.Parse(settings.OpAMPServerURL)

client/httpclient_test.go

@@ -12,6 +12,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 	"github.com/stretchr/testify/require"
@@ -433,3 +434,62 @@ func TestHTTPReportsAvailableComponents(t *testing.T) {
 		})
 	}
 }
+
+func TestHTTPSenderOpAMPInstanceUIDHeader(t *testing.T) {
+	client := NewHTTP(nil)
+
+	var instanceUids [2][16]byte
+
+	// We run twice, once with initial instance UID 1, then with instance UID 2 that server
+	// asks the client to accept, to verify both scenarios.
+	for i := 0; i < 2; i++ {
+		instanceUids[i] = [16]byte{byte(i + 1)}
+	}
+
+	// Start a server.
+	srv := internal.StartMockServer(t)
+	var connCnt atomic.Int32
+	srv.OnConnect = func(r *http.Request) {
+		// Get request header
+		hdrUid := r.Header.Get("OpAMP-Instance-UID")
+
+		// Get expected UID
+		uidIdx := connCnt.Load()
+		if uidIdx > 1 {
+			uidIdx = 1
+		}
+		uid, err := uuid.FromBytes(instanceUids[uidIdx][:])
+		require.NoError(t, err)
+
+		// Make sure we got expected header
+		assert.EqualValues(t, uid.String(), hdrUid)
+
+		connCnt.Add(1)
+	}
+	srv.OnMessage = func(msg *protobufs.AgentToServer) *protobufs.ServerToAgent {
+		return &protobufs.ServerToAgent{
+			InstanceUid: msg.InstanceUid,
+			AgentIdentification: &protobufs.AgentIdentification{
+				NewInstanceUid: instanceUids[1][:], // Ask client to change its Instance UID
+			},
+			Flags: uint64(protobufs.ServerToAgentFlags_ServerToAgentFlags_ReportFullState),
+		}
+	}
+
+	header := http.Header{}
+
+	// Start a client.
+	settings := types.StartSettings{
+		OpAMPServerURL: "ws://" + srv.Endpoint,
+		Header:         header,
+		InstanceUid:    instanceUids[0],
+	}
+	startClient(t, settings, client)
+
+	// Wait for 2 connection attempts.
+	eventually(t, func() bool { return connCnt.Load() >= 2 })
+
+	// Shutdown the Server and the client.
+	srv.Close()
+	_ = client.Stop(context.Background())
+}

client/internal/httpsender.go

@@ -15,6 +15,7 @@ import (
 	"time"
 
 	"github.com/cenkalti/backoff/v4"
+	"github.com/google/uuid"
 	"google.golang.org/protobuf/proto"
 
 	"github.com/open-telemetry/opamp-go/client/internal/utils"
@@ -348,11 +349,17 @@ func (h *HTTPSender) prepareRequest(ctx context.Context) (*requestWrapper, error
 	} else {
 		req.bodyReader = bodyReader(data)
 	}
-	if err != nil {
-		return nil, err
-	}
 
 	req.Header = h.getHeader()
+
+	if msgToSend.InstanceUid != nil {
+		uid, err := uuid.FromBytes(msgToSend.InstanceUid)
+		if err != nil {
+			return nil, err
+		}
+		req.Header.Add(headerOpAMPInstanceUID, uid.String())
+	}
+
 	return &req, nil
 }
 

client/internal/httpsender_test.go

@@ -13,7 +13,9 @@ import (
 	"testing"
 	"time"
 
+	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/open-telemetry/opamp-go/client/types"
 	sharedinternal "github.com/open-telemetry/opamp-go/internal"
@@ -708,3 +710,32 @@ func setupTestSender(_ *testing.T, url string) *HTTPSender {
 	sender.url = url
 	return sender
 }
+
+func TestHTTPSenderOpAMPInstanceUIDHeader(t *testing.T) {
+	uidBytes := []byte{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}
+	uid, err := uuid.FromBytes(uidBytes)
+	require.NoError(t, err)
+
+	srv := StartMockServer(t)
+	srv.OnRequest = func(w http.ResponseWriter, r *http.Request) {
+		assert.EqualValues(t, r.Header.Get(headerOpAMPInstanceUID), uid.String())
+		w.WriteHeader(http.StatusOK)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	url := "http://" + srv.Endpoint
+	sender := NewHTTPSender(&sharedinternal.NopLogger{})
+
+	sender.NextMessage().Update(func(msg *protobufs.AgentToServer) {
+		msg.InstanceUid = uidBytes
+	})
+	sender.callbacks = types.Callbacks{
+		OnConnect: func(ctx context.Context) {},
+	}
+
+	sender.url = url
+	resp, err := sender.sendRequestWithRetries(ctx)
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+	cancel()
+	srv.Close()
+}

client/internal/mockserver.go

@@ -35,8 +35,9 @@ type MockServer struct {
 }
 
 const (
-	headerContentType   = "Content-Type"
-	contentTypeProtobuf = "application/x-protobuf"
+	headerContentType      = "Content-Type"
+	contentTypeProtobuf    = "application/x-protobuf"
+	headerOpAMPInstanceUID = "OpAMP-Instance-UID"
 )
 
 func newMockServer(t *testing.T) (*MockServer, *http.ServeMux) {