Out-of-the-box "Agent mode" support for antctl on Windows (antrea-io#…

…3645)

* Out-of-the-box "Agent mode" support for antctl

At the moment is is possible to run antctl in Agent mode from a Windows
Node on which Antrea is runing, but it requires setting the following
environment variables manually:
```
> $Env:POD_NAME="antrea-agent"
> $Env:KUBERNETES_SERVICE_HOST="<ClusterIP>"
> $Env:KUBERNETES_SERVICE_PORT="443"
```

This is not very convenient and it is not documented
either. Additionally, there is no reason to require
KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT in Agent mode. This
requirement is caused by a bug in the antctl code: when antctl is
running inside a Pod, there is no need to resolve the "in-cluster"
Kubeconfig, as we generate this config manually to connect to the Antrea
API server.

In order to make antctl work out-of-the-box for that case, we change the
logic which decides what the antctl "runtime mode" is: if the antctl
binary is running on Windows and if a loopback client token exists, we
assume that this is a Windows Node which is running the Antrea Agent.

Fixes antrea-io#2104

Signed-off-by: Antonin Bas <[email protected]>

* Run antctl e2e tests for clusters with Windows Nodes

Signed-off-by: Antonin Bas <[email protected]>

pkg/antctl/client.go

@@ -71,12 +71,9 @@ func newClient(codec serializer.CodecFactory) AntctlClient {
 // It will return error if the stating of the file failed or the kubeconfig is malformed.
 // If the default kubeconfig not exists, it will try to use an in-cluster config.
 func (c *client) resolveKubeconfig(opt *requestOption) (*rest.Config, error) {
-	kubeconfig, err := runtime.ResolveKubeconfig(opt.kubeconfig)
-	if err != nil {
-		return nil, err
-	}
-	kubeconfig.NegotiatedSerializer = c.codec
+	var kubeconfig *rest.Config
 	if runtime.InPod {
+		kubeconfig = &rest.Config{}
 		kubeconfig.Insecure = true
 		kubeconfig.CAFile = ""
 		kubeconfig.CAData = nil
@@ -90,7 +87,13 @@ func (c *client) resolveKubeconfig(opt *requestOption) (*rest.Config, error) {
 			kubeconfig.Host = net.JoinHostPort("127.0.0.1", fmt.Sprint(apis.FlowAggregatorAPIPort))
 			kubeconfig.BearerTokenFile = flowaggregatorapiserver.TokenPath
 		}
+	} else {
+		var err error
+		if kubeconfig, err = runtime.ResolveKubeconfig(opt.kubeconfig); err != nil {
+			return nil, err
+		}
 	}
+	kubeconfig.NegotiatedSerializer = c.codec
 	return kubeconfig, nil
 }
 

pkg/antctl/runtime/runtime.go

@@ -20,6 +20,9 @@ import (
 
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
+
+	agentapiserver "antrea.io/antrea/pkg/agent/apiserver"
+	"antrea.io/antrea/pkg/util/runtime"
 )
 
 const (
@@ -53,6 +56,15 @@ func init() {
 	podName, found := os.LookupEnv("POD_NAME")
 	InPod = found && (strings.HasPrefix(podName, "antrea-agent") || strings.HasPrefix(podName, "antrea-controller") ||
 		strings.HasPrefix(podName, "flow-aggregator"))
+
+	if runtime.IsWindowsPlatform() && !InPod {
+		if _, err := os.Stat(agentapiserver.TokenPath); err == nil {
+			InPod = true
+			Mode = ModeAgent
+			return
+		}
+	}
+
 	if strings.HasPrefix(podName, "antrea-agent") {
 		Mode = ModeAgent
 	} else if strings.HasPrefix(podName, "flow-aggregator") {

test/e2e/antctl_test.go

@@ -36,7 +36,6 @@ type cmdAndReturnCode struct {
 // TestAntctl is the top-level test which contains all subtests for
 // Antctl related test cases as they can share setup, teardown.
 func TestAntctl(t *testing.T) {
-	skipIfHasWindowsNodes(t)
 	skipIfNotRequired(t, "mode-irrelevant")
 
 	data, err := setupTest(t)