Allow overriding the platform used for default keybindings

docs-master/Config.md

@@ -1059,6 +1059,12 @@ keybinding:
     edit: <disabled> # disable 'edit file'
 ```
 
+### Overriding the platform for default keybindings
+
+A few keybindings have different defaults on macOS than on Linux and Windows (e.g. word-wise cursor movement in text inputs uses `alt` on macOS but `ctrl` elsewhere). Lazygit picks these based on the OS it's running on, but you can override that with the `LAZYGIT_KEYBINDING_PLATFORM` environment variable. Set it to `darwin`, `linux`, or `windows`; any other value is ignored and the actual OS is used.
+
+This is useful when running lazygit in a Linux container that you access over ssh from a Mac, where you'd rather use the macOS keybindings.
+
 ### Example Keybindings For Colemak Users
 
 ```yaml

pkg/app/entry_point.go

@@ -102,7 +102,7 @@ func Start(buildInfo *BuildInfo, integrationTest integrationTypes.IntegrationTes
 	if cliArgs.PrintDefaultConfig {
 		var buf bytes.Buffer
 		encoder := yaml.NewEncoder(&buf)
-		err := encoder.Encode(config.GetDefaultConfigForPlatform(runtime.GOOS))
+		err := encoder.Encode(config.GetDefaultConfigForPlatform(config.KeybindingPlatform()))
 		if err != nil {
 			log.Fatal(err.Error())
 		}

pkg/config/app_config.go

@@ -136,8 +136,23 @@ func findOrCreateConfigDir() (string, error) {
 	return folder, os.MkdirAll(folder, 0o755)
 }
 
+// KeybindingPlatform returns the platform whose default keybindings should be
+// used. Normally this is the OS we're running on, but it can be overridden with
+// the LAZYGIT_KEYBINDING_PLATFORM environment variable; this is useful e.g. when
+// running lazygit in a Linux container that you access over ssh from a Mac, and
+// you'd rather use the Mac keybindings. An unrecognized value falls back to the
+// real OS, which gives meaningful bindings, rather than to the (arbitrary)
+// non-darwin defaults.
+func KeybindingPlatform() string {
+	platform := os.Getenv("LAZYGIT_KEYBINDING_PLATFORM")
+	if lo.Contains([]string{"darwin", "linux", "windows"}, platform) {
+		return platform
+	}
+	return runtime.GOOS
+}
+
 func loadUserConfigWithDefaults(configFiles []*ConfigFile, isGuiInitialized bool) (*UserConfig, error) {
-	return loadUserConfig(configFiles, GetDefaultConfigForPlatform(runtime.GOOS), isGuiInitialized)
+	return loadUserConfig(configFiles, GetDefaultConfigForPlatform(KeybindingPlatform()), isGuiInitialized)
 }
 
 func loadUserConfig(configFiles []*ConfigFile, base *UserConfig, isGuiInitialized bool) (*UserConfig, error) {

pkg/config/app_config_test.go

@@ -1,11 +1,53 @@
 package config
 
 import (
+	"runtime"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 )
 
+func TestKeybindingPlatform(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		envValue string
+		expected string
+	}{
+		{
+			name:     "Not set falls back to the host OS",
+			envValue: "",
+			expected: runtime.GOOS,
+		},
+		{
+			name:     "darwin is honored",
+			envValue: "darwin",
+			expected: "darwin",
+		},
+		{
+			name:     "linux is honored",
+			envValue: "linux",
+			expected: "linux",
+		},
+		{
+			name:     "windows is honored",
+			envValue: "windows",
+			expected: "windows",
+		},
+		{
+			name:     "An unrecognized value falls back to the host OS",
+			envValue: "mac",
+			expected: runtime.GOOS,
+		},
+	}
+
+	for _, s := range scenarios {
+		t.Run(s.name, func(t *testing.T) {
+			t.Setenv("LAZYGIT_KEYBINDING_PLATFORM", s.envValue)
+			assert.Equal(t, s.expected, KeybindingPlatform())
+		})
+	}
+}
+
 func TestMigrationOfRenamedKeys(t *testing.T) {
 	scenarios := []struct {
 		name              string