NETOBSERV-617: split big payloads in GRPC exporter (#81)

Author: Mario Macias

docs/config.md

@@ -5,6 +5,8 @@ The following environment variables are available to configure the NetObserv eBF
 * `EXPORT` (default: `grpc`). Flows' exporter protocol. Accepted values are: `grpc` or `kafka` or `ipfix+tcp` or `ipfix+udp`.
 * `FLOWS_TARGET_HOST` (required if `EXPORT` is `grpc` or `ipfix+[tcp/udp]`). Host name or IP of the target Flow collector.
 * `FLOWS_TARGET_PORT` (required if `EXPORT` is `grpc` or `ipfix+[tcp/udp]`). Port of the target flow collector.
+* `GRPC_MESSAGE_MAX_FLOWS` (default: `10000`). Specifies the limit, in number of flows, of each GRPC
+  message. Messages larger than that number will be split and submitted sequentially.
 * `AGENT_IP` (optional). Allows overriding the reported Agent IP address on each flow.
 * `AGENT_IP_IFACE` (default: `external`). Specifies which interface should the agent pick the IP
   address from in order to report it in the AgentIP field on each flow. Accepted values are:

pkg/agent/agent.go

@@ -193,7 +193,7 @@ func buildFlowExporter(cfg *Config) (node.TerminalFunc[[]*flow.Record], error) {
 				cfg.TargetHost, cfg.TargetPort)
 		}
 		target := fmt.Sprintf("%s:%d", cfg.TargetHost, cfg.TargetPort)
-		grpcExporter, err := exporter.StartGRPCProto(target)
+		grpcExporter, err := exporter.StartGRPCProto(target, cfg.GRPCMessageMaxFlows)
 		if err != nil {
 			return nil, err
 		}

pkg/agent/config.go

@@ -42,6 +42,9 @@ type Config struct {
 	TargetHost string `env:"FLOWS_TARGET_HOST"`
 	// TargetPort is the port the target Flow collector, when the EXPORT variable is set to "grpc"
 	TargetPort int `env:"FLOWS_TARGET_PORT"`
+	// GRPCMessageMaxFlows specifies the limit, in number of flows, of each GRPC message. Messages
+	// larger than that number will be split and submitted sequentially.
+	GRPCMessageMaxFlows int `env:"GRPC_MESSAGE_MAX_FLOWS" envDefault:"10000"`
 	// Interfaces contains the interface names from where flows will be collected. If empty, the agent
 	// will fetch all the interfaces in the system, excepting the ones listed in ExcludeInterfaces.
 	// If an entry is enclosed by slashes (e.g. `/br-/`), it will match as regular expression,

pkg/exporter/grpc_proto.go

@@ -16,16 +16,21 @@ var glog = logrus.WithField("component", "exporter/GRPCProto")
 type GRPCProto struct {
 	hostPort   string
 	clientConn *grpc.ClientConnection
+	// maxFlowsPerMessage limits the maximum number of flows per GRPC message.
+	// If a message contains more flows than this number, the GRPC message will be split into
+	// multiple messages.
+	maxFlowsPerMessage int
 }
 
-func StartGRPCProto(hostPort string) (*GRPCProto, error) {
+func StartGRPCProto(hostPort string, maxFlowsPerMessage int) (*GRPCProto, error) {
 	clientConn, err := grpc.ConnectClient(hostPort)
 	if err != nil {
 		return nil, err
 	}
 	return &GRPCProto{
-		hostPort:   hostPort,
-		clientConn: clientConn,
+		hostPort:           hostPort,
+		clientConn:         clientConn,
+		maxFlowsPerMessage: maxFlowsPerMessage,
 	}, nil
 }
 
@@ -34,10 +39,11 @@ func StartGRPCProto(hostPort string) (*GRPCProto, error) {
 func (g *GRPCProto) ExportFlows(input <-chan []*flow.Record) {
 	log := glog.WithField("collector", g.hostPort)
 	for inputRecords := range input {
-		pbRecords := flowsToPB(inputRecords)
-		log.Debugf("sending %d records", len(pbRecords.Entries))
-		if _, err := g.clientConn.Client().Send(context.TODO(), pbRecords); err != nil {
-			log.WithError(err).Error("couldn't send flow records to collector")
+		for _, pbRecords := range flowsToPB(inputRecords, g.maxFlowsPerMessage) {
+			log.Debugf("sending %d records", len(pbRecords.Entries))
+			if _, err := g.clientConn.Client().Send(context.TODO(), pbRecords); err != nil {
+				log.WithError(err).Error("couldn't send flow records to collector")
+			}
 		}
 	}
 	if err := g.clientConn.Close(); err != nil {

pkg/exporter/grpc_proto_test.go

@@ -6,6 +6,8 @@ import (
 	"testing"
 	"time"
 
+	test2 "github.com/netobserv/netobserv-ebpf-agent/pkg/test"
+
 	"github.com/mariomac/guara/pkg/test"
 	"github.com/netobserv/netobserv-ebpf-agent/pkg/flow"
 	"github.com/netobserv/netobserv-ebpf-agent/pkg/grpc"
@@ -21,11 +23,12 @@ func TestGRPCProto_ExportFlows_AgentIP(t *testing.T) {
 	port, err := test.FreeTCPPort()
 	require.NoError(t, err)
 	serverOut := make(chan *pbflow.Records)
-	_, err = grpc.StartCollector(port, serverOut)
+	coll, err := grpc.StartCollector(port, serverOut)
 	require.NoError(t, err)
+	defer coll.Close()
 
 	// Start GRPCProto exporter stage
-	exporter, err := StartGRPCProto(fmt.Sprintf("127.0.0.1:%d", port))
+	exporter, err := StartGRPCProto(fmt.Sprintf("127.0.0.1:%d", port), 1000)
 	require.NoError(t, err)
 
 	// Send some flows to the input of the exporter stage
@@ -37,23 +40,14 @@ func TestGRPCProto_ExportFlows_AgentIP(t *testing.T) {
 		{RawRecord: flow.RawRecord{RecordKey: flow.RecordKey{EthProtocol: flow.IPv6Type}},
 			AgentIP: net.ParseIP("8888::1111")},
 	}
-	close(flows)
 	go exporter.ExportFlows(flows)
 
-	var rs *pbflow.Records
-	select {
-	case rs = <-serverOut:
-	case <-time.After(timeout):
-		require.Fail(t, "timeout waiting for flows")
-	}
+	rs := test2.ReceiveTimeout(t, serverOut, timeout)
 	assert.Len(t, rs.Entries, 1)
 	r := rs.Entries[0]
 	assert.EqualValues(t, 0x0a090807, r.GetAgentIp().GetIpv4())
-	select {
-	case rs = <-serverOut:
-	case <-time.After(timeout):
-		require.Fail(t, "timeout waiting for flows")
-	}
+
+	rs = test2.ReceiveTimeout(t, serverOut, timeout)
 	assert.Len(t, rs.Entries, 1)
 	r = rs.Entries[0]
 	assert.EqualValues(t, net.ParseIP("8888::1111"), r.GetAgentIp().GetIpv6())
@@ -65,3 +59,45 @@ func TestGRPCProto_ExportFlows_AgentIP(t *testing.T) {
 		//ok!
 	}
 }
+
+func TestGRPCProto_SplitLargeMessages(t *testing.T) {
+	// start remote ingestor
+	port, err := test.FreeTCPPort()
+	require.NoError(t, err)
+	serverOut := make(chan *pbflow.Records)
+	coll, err := grpc.StartCollector(port, serverOut)
+	require.NoError(t, err)
+	defer coll.Close()
+
+	const msgMaxLen = 10000
+	// Start GRPCProto exporter stage
+	exporter, err := StartGRPCProto(fmt.Sprintf("127.0.0.1:%d", port), msgMaxLen)
+	require.NoError(t, err)
+
+	// Send a message much longer than the limit length
+	flows := make(chan []*flow.Record, 10)
+	var input []*flow.Record
+	for i := 0; i < 25000; i++ {
+		input = append(input, &flow.Record{RawRecord: flow.RawRecord{RecordKey: flow.RecordKey{
+			EthProtocol: flow.IPv6Type,
+		}}, AgentIP: net.ParseIP("1111::1111"), Interface: "12345678"})
+	}
+	flows <- input
+	go exporter.ExportFlows(flows)
+
+	// expect that the submitted message is split in chunks no longer than msgMaxLen
+	rs := test2.ReceiveTimeout(t, serverOut, timeout)
+	assert.Len(t, rs.Entries, msgMaxLen)
+	rs = test2.ReceiveTimeout(t, serverOut, timeout)
+	assert.Len(t, rs.Entries, msgMaxLen)
+	rs = test2.ReceiveTimeout(t, serverOut, timeout)
+	assert.Len(t, rs.Entries, 5000)
+
+	// after all the operation, no more flows are sent
+	select {
+	case rs = <-serverOut:
+		assert.Failf(t, "shouldn't have received any flow", "Got: %#v", rs)
+	default:
+		//ok!
+	}
+}

pkg/exporter/proto.go

@@ -11,14 +11,21 @@ import (
 
 // flowsToPB is an auxiliary function to convert flow records, as returned by the eBPF agent,
 // into protobuf-encoded messages ready to be sent to the collector via GRPC
-func flowsToPB(inputRecords []*flow.Record) *pbflow.Records {
+func flowsToPB(inputRecords []*flow.Record, maxLen int) []*pbflow.Records {
 	entries := make([]*pbflow.Record, 0, len(inputRecords))
 	for _, record := range inputRecords {
 		entries = append(entries, flowToPB(record))
 	}
-	return &pbflow.Records{
-		Entries: entries,
+	var records []*pbflow.Records
+	for len(entries) > 0 {
+		end := len(entries)
+		if end > maxLen {
+			end = maxLen
+		}
+		records = append(records, &pbflow.Records{Entries: entries[:end]})
+		entries = entries[end:]
 	}
+	return records
 }
 
 // flowsToPB is an auxiliary function to convert a single flow record, as returned by the eBPF agent,

pkg/test/channels.go

@@ -0,0 +1,20 @@
+package test
+
+import (
+	"testing"
+	"time"
+)
+
+// ReceiveTimeout returns the first received element or fails the test if nothing is received
+// before the given timeout
+func ReceiveTimeout[T any](t *testing.T, ch <-chan T, timeout time.Duration) T {
+	t.Helper()
+	select {
+	case e := <-ch:
+		return e
+	case <-time.After(timeout):
+		var z T
+		t.Fatalf("timeout while waiting %s for a %T element in channel", timeout, z)
+		return z
+	}
+}