Support setting extra entries for PATH env variable on Windows hosts

During startup `limactl.exe` will check new experimental
`_LIMA_WINDOWS_EXTRA_PATH` environment variable and when found it
will be added to PATH environment variable for the running process.

Signed-off-by: Arthur Sengileyev <[email protected]>

Author: arixmkii

cmd/limactl/main.go

@@ -28,6 +28,16 @@ const (
 )
 
 func main() {
+	if runtime.GOOS == "windows" {
+		extras, hasExtra := os.LookupEnv("_LIMA_WINDOWS_EXTRA_PATH")
+		if hasExtra && strings.TrimSpace(extras) != "" {
+			p := os.Getenv("PATH")
+			err := os.Setenv("PATH", strings.TrimSpace(extras)+string(filepath.ListSeparator)+p)
+			if err != nil {
+				logrus.Warning("Can't add extras to PATH, relying entirely on system PATH")
+			}
+		}
+	}
 	if err := newApp().Execute(); err != nil {
 		handleExitCoder(err)
 		logrus.Fatal(err)

pkg/qemu/qemu.go

@@ -602,10 +602,10 @@ func Cmdline(ctx context.Context, cfg Config) (exe string, args []string, err er
 	if !legacyBIOS {
 		var firmware string
 		firmwareInBios := runtime.GOOS == "windows"
-		if envVar := os.Getenv("LIMA_QEMU_UEFI_IN_BIOS"); envVar != "" {
-			b, err := strconv.ParseBool(os.Getenv("LIMA_QEMU_UEFI_IN_BIOS"))
+		if envVar := os.Getenv("_LIMA_QEMU_UEFI_IN_BIOS"); envVar != "" {
+			b, err := strconv.ParseBool(os.Getenv("_LIMA_QEMU_UEFI_IN_BIOS"))
 			if err != nil {
-				logrus.WithError(err).Warnf("invalid LIMA_QEMU_UEFI_IN_BIOS value %q", envVar)
+				logrus.WithError(err).Warnf("invalid _LIMA_QEMU_UEFI_IN_BIOS value %q", envVar)
 			} else {
 				firmwareInBios = b
 			}

website/content/en/docs/config/environment-variables.md

@@ -67,13 +67,27 @@ This page documents the environment variables used in Lima.
   export LIMA_USERNET_RESOLVE_IP_ADDRESS_TIMEOUT=5
   ```
 
-### `LIMA_QEMU_UEFI_IN_BIOS`
+### `_LIMA_QEMU_UEFI_IN_BIOS`
 
 - **Description**: Commands QEMU to load x86_64 UEFI images using `-bios` instead of `pflash` drives.
 - **Default**: `false` on Unix like hosts and `true` on Windows hosts
 - **Usage**: 
   ```sh
-  export LIMA_QEMU_UEFI_IN_BIOS=true
+  export _LIMA_QEMU_UEFI_IN_BIOS=true
   ```
 - **Note**: It is expected that this variable will be set to `false` by default in future
   when QEMU supports `pflash` UEFI for accelerated guests on Windows.
+
+### `_LIMA_WINDOWS_EXTRA_PATH`
+
+- **Description**: Additional directories which will be added to PATH by `limactl.exe` process to search for tools.
+  It is useful, when there is a need to prevent collisions between binaries available in active shell and ones
+  used by `limactl.exe` - injecting them only for the running process w/o altering PATH observed by user shell.
+  Is is Windows specific and does nothing for other platforms.
+- **Default**: unset
+- **Usage**:
+  ```bat
+  set _LIMA_WINDOWS_EXTRA_PATH=C:\Program Files\Git\usr\bin
+  ```
+- **Note**: It is an experimental setting and has no guarantees being ever promoted to stable. It may be removed
+  or changed at any stage of project development.