Add make target to enable debugger during test run

Signed-off-by: Yevhen Vydolob <yvydolob@redhat.com>

DEVELOPMENT.md

@@ -0,0 +1,86 @@
+### Debugging test
+
+#### MacOS
+
+You could debug tests with [Delve](https://github.com/go-delve/delve) debugger.
+Run:
+```shell
+make test-mac-debug
+```
+This command will run build `gvisor` binary with debugger enabled.
+
+>Note: By default it would use `--continue` `dlv` option to not pause `gvisor` execution on start, if debugger is not connected.
+> To pause `gvisor` execution until debugger is connected just remove `"--continue"` parameter from this [line](./test-vfkit/vfkit_suite_test.go#L93) 
+
+And debug server with `2345` port, you could use any `delve` client to interact with debugger
+
+##### GoLand Example
+Create new `Go Remote` debug configuration:
+1. Click Edit | Run Configurations. Alternatively, click the list of run/debug configurations on the toolbar and select Edit Configurations.
+2. In the Run/Debug Configurations dialog, click the Add button (the Add button) and select Go Remote.
+3. Set meaningful name
+4. In the Host field, keep `localhost`
+5. In the Port field, keep `2345` port number
+6. Click **OK** button
+
+Run `gvisor` tests with debug with:
+```shell
+make test-mac-debug
+```
+wait until `Listening for remote connections (connections are not authenticated nor encrypted)` message it appears.
+Click on debug button on Golang, ensure that your `Go Remote` profile is selected.
+
+Have fun with debugging.
+
+##### VSCode
+Create/edit `launch.json` by adding this configuration:
+```json
+   {
+      "name": "Connect to Gvisor",
+      "type": "go",
+      "request": "attach",
+      "mode": "remote",
+      "remotePath": "${workspaceFolder}",
+      "port": 2345,
+      "host": "localhost"
+    }
+```
+Run `gvisor` tests with debug with:
+```shell
+make test-mac-debug
+```
+wait until `Listening for remote connections (connections are not authenticated nor encrypted)` message it appears.
+Execute the launch attach request(`Connect to Gvisor`).
+
+Have fun with debugging.
+
+##### CLI Example
+
+Connect to debugger server with:
+```shell
+dlv connect :2345
+```
+Example of usage:
+```shell
+Type 'help' for list of commands.
+(dlv) break main.main
+Breakpoint 1 set at 0xe735776 for main.main() ./work/redhat/gvisor-tap-vsock/cmd/gvproxy/main.go:59
+(dlv) continue
+> [Breakpoint 1] main.main() ./work/redhat/gvisor-tap-vsock/cmd/gvproxy/main.go:59 (hits goroutine(1):1 total:1) (PC: 0xe735776)
+    54:         hostIP      = "192.168.127.254"
+    55:         host        = "host"
+    56:         gateway     = "gateway"
+    57: )
+    58:
+=>  59: func main() {
+    60:         version := types.NewVersion("gvproxy")
+    61:         version.AddFlag()
+    62:         flag.Var(&endpoints, "listen", "control endpoint")
+    63:         flag.BoolVar(&debug, "debug", false, "Print debug info")
+    64:         flag.IntVar(&mtu, "mtu", 1500, "Set the MTU")
+```
+More info about CLI client [here](https://github.com/go-delve/delve/blob/master/Documentation/cli/README.md)
+
+#### Editor integration
+
+For available editor integration look [there](https://github.com/go-delve/delve/blob/master/Documentation/EditorIntegration.md)

Makefile

@@ -78,3 +78,8 @@ test-qemu: gvproxy test-companion
 .PHONY: test-mac
 test-mac: gvproxy
 	go test -timeout 20m  -v ./test-vfkit
+
+.PHONY: test-mac-debug
+test-mac-debug:
+	go test -timeout 20m  -v ./test-vfkit --debug
+	rm -f ./test-vfkit/__debug_bin*

README.md

@@ -207,3 +207,6 @@ This is the same behaviour as [slirp](https://wiki.qemu.org/index.php/Documentat
 2. Each time, a client sends a http request, the process creates and sends the appropriate Ethernet packets to the VM.
 3. The tap device receives the packets and injects them in the kernel.
 4. The http server receives the request and send back the response.
+
+### Development
+Developers who want to work on gvisor-tap-vsock should visit the [Development](./DEVELOPMENT.md) document.

test-vfkit/vfkit_suite_test.go

@@ -46,14 +46,18 @@ var (
 	privateKeyFile string
 	publicKeyFile  string
 	ignFile        string
+	cmdDir         string
 )
 
+var debugEnabled = flag.Bool("debug", false, "enable debugger")
+
 func init() {
 	flag.StringVar(&tmpDir, "tmpDir", "../tmp", "temporary working directory")
 	flag.StringVar(&binDir, "bin", "../bin", "directory with compiled binaries")
 	privateKeyFile = filepath.Join(tmpDir, "id_test")
 	publicKeyFile = privateKeyFile + ".pub"
 	ignFile = filepath.Join(tmpDir, "test.ign")
+	cmdDir = filepath.Join("../cmd")
 }
 
 var _ = ginkgo.BeforeSuite(func() {
@@ -86,9 +90,17 @@ var _ = ginkgo.BeforeSuite(func() {
 outer:
 	for panics := 0; ; panics++ {
 		_ = os.Remove(sock)
+		_ = os.Remove(vfkitSock)
 
-		// #nosec
-		host = exec.Command(filepath.Join(binDir, "gvproxy"), fmt.Sprintf("--ssh-port=%d", sshPort), fmt.Sprintf("--listen=unix://%s", sock), fmt.Sprintf("--listen-vfkit=unixgram://%s", vfkitSock))
+		gvproxyArgs := []string{fmt.Sprintf("--ssh-port=%d", sshPort), fmt.Sprintf("--listen=unix://%s", sock), fmt.Sprintf("--listen-vfkit=unixgram://%s", vfkitSock)}
+		if *debugEnabled {
+			dlvArgs := []string{"debug", "--headless", "--listen=:2345", "--api-version=2", "--accept-multiclient", filepath.Join(cmdDir, "gvproxy"), "--"}
+			dlvArgs = append(dlvArgs, gvproxyArgs...)
+			host = exec.Command("dlv", dlvArgs...)
+		} else {
+			// #nosec
+			host = exec.Command(filepath.Join(binDir, "gvproxy"), gvproxyArgs...)
+		}
 
 		host.Stderr = os.Stderr
 		host.Stdout = os.Stdout
@@ -103,7 +115,7 @@ outer:
 		for {
 			_, err := os.Stat(sock)
 			if os.IsNotExist(err) {
-				log.Info("waiting for socket")
+				log.Info("waiting for vfkit-api socket")
 				time.Sleep(100 * time.Millisecond)
 				continue
 			}