Fix test failure of ServiceExternalIP with LoadBalancerModeDSR

Fixes: antrea-io#6992

Signed-off-by: Xu Liu <[email protected]>

test/e2e/service_externalip_test.go

@@ -779,6 +779,26 @@ func testExternalIPAccess(t *testing.T, data *TestData) {
 					externalIP, host, err := waitExternalIPConfigured(service)
 					require.NoError(t, err)
 
+					// A route to the client IP is required for DSR mode.
+					nodeInfo := getNodeByName(host)
+					workerNodeIP := clusterInfo.nodes[nodeInfo.idx].ip()
+					addRouteToClientIPCmd := []string{"ip", "route", "replace", tt.clientIP, "via", workerNodeIP}
+					delRouteToClientIPCmd := []string{"ip", "route", "del", tt.clientIP, "via", workerNodeIP}
+
+					for idx := range nodes {
+						node := nodes[idx]
+						if node == host {
+							continue
+						}
+						stdout, stderr, err := data.RunCommandFromAntreaPodOnNode(node, addRouteToClientIPCmd)
+						require.NoError(t, err, "Failed to add route to client IP on Node %s, stdout: %s, stderr: %s: cmd: %q", node, stdout, stderr, addRouteToClientIPCmd)
+
+						defer func() {
+							stdout, stderr, err := data.RunCommandFromAntreaPodOnNode(node, delRouteToClientIPCmd)
+							assert.NoError(t, err, "Failed to delete route to client IP on Node %s, stdout: %s, stderr: %s", node, stdout, stderr)
+						}()
+					}
+
 					// Create a pod in a different netns with the same subnet of the external IP to mock as another Node in the same subnet.
 					cmd, netns := getCommandInFakeExternalNetwork("sleep 3600", tt.clientIPMaskLen, tt.clientIP, tt.localIP)