Support running integration tests on macOS

Since `make docker-test-integration` runs the integration tests in a
Docker image, it is reasonnable to expect that one may be able to run
these tests on macOS (Docker Desktop). This required the following 2
changes:

 * OVS bridges should use the netdev datpath type, since the kernel
   datapath does not seem to be available in the KyperKit VM.
 * The HyperKit VM seems to enable ipip, which means that some extra
   tunnel interfaces are created in the network namepsaces that our
   tests create inside the Docker container. As a result our CNI
   integration tests need to be "relaxed" to accomodate for these.

Fixes #783

test/integration/agent/cniserver_test.go

@@ -417,7 +417,21 @@ func (tester *cmdAddDelTester) cmdAddTest(tc testCase, dataDir string) (*current
 		return err
 	})
 	testRequire.Nil(err)
-	testRequire.Len(linkList, 2)
+	// when running the integration tests in a Docker image on macOS (Docker
+	// Desktop), we observe that the namespace includes 4 links, not 2
+	// (localhost and veth). It seems that the HyperKit Linux VM loads the
+	// ipip module, which means that the Linux Kernel creates 2 extra
+	// interfaces in each namespace (tunl0 and ip6tnl).
+	testRequire.GreaterOrEqual(len(linkList), 2)
+	// check that the list includes the eth0 veth
+	vethFound := false
+	for _, link := range linkList {
+		if link.Type() == "veth" && link.Attrs().Name == IFName {
+			vethFound = true
+			break
+		}
+	}
+	testRequire.Truef(vethFound, "Missing '%s' veth in target namespace", IFName)
 
 	// Find the veth peer in the container namespace and the default route.
 	tester.checkContainerNetworking(tc)

test/integration/ovs/openflow_test_utils.go

@@ -25,7 +25,10 @@ import (
 )
 
 func PrepareOVSBridge(brName string) error {
-	cmdStr := fmt.Sprintf("ovs-vsctl --may-exist add-br %s -- set Bridge %s protocols='OpenFlow10,OpenFlow13'", brName, brName)
+	// using the netdev datapath type does not impact test coverage but
+	// ensures that the integration tests can be run with Docker Desktop on
+	// macOS.
+	cmdStr := fmt.Sprintf("ovs-vsctl --may-exist add-br %s -- set Bridge %s protocols='OpenFlow10,OpenFlow13' datapath_type=netdev", brName, brName)
 	err := exec.Command("/bin/sh", "-c", cmdStr).Run()
 	if err != nil {
 		return err

test/integration/ovs/ovs_client_test.go

@@ -59,7 +59,10 @@ func (data *testData) setup(t *testing.T) {
 		t.Fatalf("Could not establish connection to %s after %s", UDSAddress, defaultConnectTimeout)
 	}
 
-	data.br = ovsconfig.NewOVSBridge(bridgeName, "system", data.ovsdb)
+	// using the netdev datapath type does not impact test coverage but
+	// ensures that the integration tests can be run with Docker Desktop on
+	// macOS.
+	data.br = ovsconfig.NewOVSBridge(bridgeName, "netdev", data.ovsdb)
 	err = data.br.Create()
 	require.Nil(t, err, "Failed to create bridge %s", bridgeName)
 }