tsnet: send less data in metrics integration test

this commit reduced the amount of data sent in the metrics
data integration test from 10MB to 1MB.

On various machines 10MB was quite flaky, while 1MB has not failed
once on 10000 runs.

Updates #13420

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

tsnet/tsnet_test.go

@@ -1015,8 +1015,8 @@ func TestUserMetrics(t *testing.T) {
 
 	mustDirect(t, t.Logf, lc1, lc2)
 
-	// 10 megabytes
+	// 1 megabytes
-	bytesToSend := 10 * 1024 * 1024
+	bytesToSend := 1 * 1024 * 1024
 
 	// This asserts generates some traffic, it is factored out
 	// of TestUDPConn.
@@ -1059,14 +1059,13 @@ func TestUserMetrics(t *testing.T) {
 		t.Errorf("metrics1, tailscaled_approved_routes: got %v, want %v", got, want)
 	}
 
-	// Verify that the amount of data recorded in bytes is higher or equal to the
+	// Verify that the amount of data recorded in bytes is higher or equal to the data sent
-	// 10 megabytes sent.
 	inboundBytes1 := parsedMetrics1[`tailscaled_inbound_bytes_total{path="direct_ipv4"}`]
 	if inboundBytes1 < float64(bytesToSend) {
 		t.Errorf(`metrics1, tailscaled_inbound_bytes_total{path="direct_ipv4"}: expected higher (or equal) than %d, got: %f`, bytesToSend, inboundBytes1)
 	}
 
-	// But ensure that it is not too much higher than the 10 megabytes sent.
+	// But ensure that it is not too much higher than the data sent.
 	if inboundBytes1 > float64(bytesToSend)*bytesSentTolerance {
 		t.Errorf(`metrics1, tailscaled_inbound_bytes_total{path="direct_ipv4"}: expected lower than %f, got: %f`, float64(bytesToSend)*bytesSentTolerance, inboundBytes1)
 	}
@@ -1093,14 +1092,13 @@ func TestUserMetrics(t *testing.T) {
 		t.Errorf("metrics2, tailscaled_approved_routes: got %v, want %v", got, want)
 	}
 
-	// Verify that the amount of data recorded in bytes is higher or equal than the
+	// Verify that the amount of data recorded in bytes is higher or equal than the data sent.
-	// 10 megabytes sent.
 	outboundBytes2 := parsedMetrics2[`tailscaled_outbound_bytes_total{path="direct_ipv4"}`]
 	if outboundBytes2 < float64(bytesToSend) {
 		t.Errorf(`metrics2, tailscaled_outbound_bytes_total{path="direct_ipv4"}: expected higher (or equal) than %d, got: %f`, bytesToSend, outboundBytes2)
 	}
 
-	// But ensure that it is not too much higher than the 10 megabytes sent.
+	// But ensure that it is not too much higher than the data sent.
 	if outboundBytes2 > float64(bytesToSend)*bytesSentTolerance {
 		t.Errorf(`metrics2, tailscaled_outbound_bytes_total{path="direct_ipv4"}: expected lower than %f, got: %f`, float64(bytesToSend)*bytesSentTolerance, outboundBytes2)
 	}