clearer separation of concerns when bootstrapping application

main.go

@@ -8,12 +8,12 @@ import (
 	"path/filepath"
 	"runtime"
 
-	"github.com/go-errors/errors"
 	"github.com/integrii/flaggy"
 	"github.com/jesseduffield/lazygit/pkg/app"
+	"github.com/jesseduffield/lazygit/pkg/app/daemon"
 	"github.com/jesseduffield/lazygit/pkg/config"
-	"github.com/jesseduffield/lazygit/pkg/constants"
 	"github.com/jesseduffield/lazygit/pkg/env"
+	"github.com/jesseduffield/lazygit/pkg/logs"
 	yaml "github.com/jesseduffield/yaml"
 )
 
@@ -117,7 +117,7 @@ func main() {
 	}
 
 	if logFlag {
-		app.TailLogs()
+		logs.TailLogs()
 		os.Exit(0)
 	}
 
@@ -138,20 +138,15 @@ func main() {
 		log.Fatal(err.Error())
 	}
 
-	app, err := app.NewApp(appConfig)
-
-	if err == nil {
-		err = app.Run(filterPath)
-	}
-
+	common, err := app.NewCommon(appConfig)
 	if err != nil {
-		if errorMessage, known := app.KnownError(err); known {
-			log.Fatal(errorMessage)
-		}
-		newErr := errors.Wrap(err, 0)
-		stackTrace := newErr.ErrorStack()
-		app.Log.Error(stackTrace)
-
-		log.Fatal(fmt.Sprintf("%s: %s\n\n%s", app.Tr.ErrorOccurred, constants.Links.Issues, stackTrace))
+		log.Fatal(err)
 	}
+
+	if daemon.InDaemonMode() {
+		daemon.Handle(common)
+		return
+	}
+
+	app.Run(appConfig, common, filterPath)
 }

pkg/app/app.go

@@ -2,10 +2,8 @@ package app
 
 import (
 	"bufio"
-	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -13,118 +11,81 @@ import (
 	"strconv"
 	"strings"
 
-	"github.com/aybabtme/humanlog"
+	"github.com/go-errors/errors"
+
 	"github.com/jesseduffield/generics/slices"
 	"github.com/jesseduffield/lazygit/pkg/commands"
 	"github.com/jesseduffield/lazygit/pkg/commands/git_config"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
 	"github.com/jesseduffield/lazygit/pkg/common"
 	"github.com/jesseduffield/lazygit/pkg/config"
+	"github.com/jesseduffield/lazygit/pkg/constants"
 	"github.com/jesseduffield/lazygit/pkg/env"
 	"github.com/jesseduffield/lazygit/pkg/gui"
 	"github.com/jesseduffield/lazygit/pkg/i18n"
 	"github.com/jesseduffield/lazygit/pkg/updates"
-	"github.com/sirupsen/logrus"
 )
 
-// App struct
+// App is the struct that's instantiated from within main.go and it manages
+// bootstrapping and running the application.
 type App struct {
 	*common.Common
-	closers       []io.Closer
-	Config        config.AppConfigurer
-	OSCommand     *oscommands.OSCommand
-	Gui           *gui.Gui
-	Updater       *updates.Updater // may only need this on the Gui
-	ClientContext string
+	closers   []io.Closer
+	Config    config.AppConfigurer
+	OSCommand *oscommands.OSCommand
+	Gui       *gui.Gui
+	Updater   *updates.Updater // may only need this on the Gui
 }
 
-type errorMapping struct {
-	originalError string
-	newError      string
-}
+func Run(config config.AppConfigurer, common *common.Common, filterPath string) {
+	app, err := NewApp(config, common)
 
-func newProductionLogger() *logrus.Logger {
-	log := logrus.New()
-	log.Out = ioutil.Discard
-	log.SetLevel(logrus.ErrorLevel)
-	return log
-}
+	if err == nil {
+		err = app.Run(filterPath)
+	}
 
-func getLogLevel() logrus.Level {
-	strLevel := os.Getenv("LOG_LEVEL")
-	level, err := logrus.ParseLevel(strLevel)
 	if err != nil {
-		return logrus.DebugLevel
+		if errorMessage, known := knownError(common.Tr, err); known {
+			log.Fatal(errorMessage)
+		}
+		newErr := errors.Wrap(err, 0)
+		stackTrace := newErr.ErrorStack()
+		app.Log.Error(stackTrace)
+
+		log.Fatal(fmt.Sprintf("%s: %s\n\n%s", common.Tr.ErrorOccurred, constants.Links.Issues, stackTrace))
 	}
-	return level
 }
 
-func newDevelopmentLogger() *logrus.Logger {
-	logger := logrus.New()
-	logger.SetLevel(getLogLevel())
-	logPath, err := config.LogPath()
-	if err != nil {
-		log.Fatal(err)
-	}
-	file, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o666)
-	if err != nil {
-		log.Fatalf("Unable to log to log file: %v", err)
-	}
-	logger.SetOutput(file)
-	return logger
-}
-
-func newLogger(config config.AppConfigurer) *logrus.Entry {
-	var log *logrus.Logger
-	if config.GetDebug() || os.Getenv("DEBUG") == "TRUE" {
-		log = newDevelopmentLogger()
-	} else {
-		log = newProductionLogger()
-	}
-
-	// highly recommended: tail -f development.log | humanlog
-	// https://github.com/aybabtme/humanlog
-	log.Formatter = &logrus.JSONFormatter{}
-
-	return log.WithFields(logrus.Fields{
-		"debug":     config.GetDebug(),
-		"version":   config.GetVersion(),
-		"commit":    config.GetCommit(),
-		"buildDate": config.GetBuildDate(),
-	})
-}
-
-// NewApp bootstrap a new application
-func NewApp(config config.AppConfigurer) (*App, error) {
+func NewCommon(config config.AppConfigurer) (*common.Common, error) {
 	userConfig := config.GetUserConfig()
 
-	app := &App{
-		closers: []io.Closer{},
-		Config:  config,
-	}
 	var err error
 	log := newLogger(config)
 	tr, err := i18n.NewTranslationSetFromConfig(log, userConfig.Gui.Language)
 	if err != nil {
-		return app, err
+		return nil, err
 	}
 
-	app.Common = &common.Common{
+	return &common.Common{
 		Log:        log,
 		Tr:         tr,
 		UserConfig: userConfig,
 		Debug:      config.GetDebug(),
+	}, nil
+}
+
+// NewApp bootstrap a new application
+func NewApp(config config.AppConfigurer, common *common.Common) (*App, error) {
+	app := &App{
+		closers: []io.Closer{},
+		Config:  config,
+		Common:  common,
 	}
 
-	// if we are being called in 'demon' mode, we can just return here
-	app.ClientContext = os.Getenv("LAZYGIT_CLIENT_COMMAND")
-	if app.ClientContext != "" {
-		return app, nil
-	}
+	app.OSCommand = oscommands.NewOSCommand(common, config, oscommands.GetPlatform(), oscommands.NewNullGuiIO(app.Log))
 
-	app.OSCommand = oscommands.NewOSCommand(app.Common, config, oscommands.GetPlatform(), oscommands.NewNullGuiIO(log))
-
-	app.Updater, err = updates.NewUpdater(app.Common, config, app.OSCommand)
+	var err error
+	app.Updater, err = updates.NewUpdater(common, config, app.OSCommand)
 	if err != nil {
 		return app, err
 	}
@@ -141,7 +102,7 @@ func NewApp(config config.AppConfigurer) (*App, error) {
 
 	gitConfig := git_config.NewStdCachedGitConfig(app.Log)
 
-	app.Gui, err = gui.NewGui(app.Common, config, gitConfig, app.Updater, showRecentRepos, dirName)
+	app.Gui, err = gui.NewGui(common, config, gitConfig, app.Updater, showRecentRepos, dirName)
 	if err != nil {
 		return app, err
 	}
@@ -243,97 +204,13 @@ func (app *App) setupRepo() (bool, error) {
 }
 
 func (app *App) Run(filterPath string) error {
-	if app.ClientContext == "INTERACTIVE_REBASE" {
-		return app.Rebase()
-	}
-
-	if app.ClientContext == "EXIT_IMMEDIATELY" {
-		os.Exit(0)
-	}
-
 	err := app.Gui.RunAndHandleError(filterPath)
 	return err
 }
 
-func gitDir() string {
-	dir := env.GetGitDirEnv()
-	if dir == "" {
-		return ".git"
-	}
-	return dir
-}
-
-// Rebase contains logic for when we've been run in demon mode, meaning we've
-// given lazygit as a command for git to call e.g. to edit a file
-func (app *App) Rebase() error {
-	app.Log.Info("Lazygit invoked as interactive rebase demon")
-	app.Log.Info("args: ", os.Args)
-
-	if strings.HasSuffix(os.Args[1], "git-rebase-todo") {
-		if err := ioutil.WriteFile(os.Args[1], []byte(os.Getenv("LAZYGIT_REBASE_TODO")), 0o644); err != nil {
-			return err
-		}
-	} else if strings.HasSuffix(os.Args[1], filepath.Join(gitDir(), "COMMIT_EDITMSG")) { // TODO: test
-		// if we are rebasing and squashing, we'll see a COMMIT_EDITMSG
-		// but in this case we don't need to edit it, so we'll just return
-	} else {
-		app.Log.Info("Lazygit demon did not match on any use cases")
-	}
-
-	return nil
-}
-
 // Close closes any resources
 func (app *App) Close() error {
 	return slices.TryForEach(app.closers, func(closer io.Closer) error {
 		return closer.Close()
 	})
 }
-
-// KnownError takes an error and tells us whether it's an error that we know about where we can print a nicely formatted version of it rather than panicking with a stack trace
-func (app *App) KnownError(err error) (string, bool) {
-	errorMessage := err.Error()
-
-	knownErrorMessages := []string{app.Tr.MinGitVersionError}
-
-	if slices.Contains(knownErrorMessages, errorMessage) {
-		return errorMessage, true
-	}
-
-	mappings := []errorMapping{
-		{
-			originalError: "fatal: not a git repository",
-			newError:      app.Tr.NotARepository,
-		},
-	}
-
-	if mapping, ok := slices.Find(mappings, func(mapping errorMapping) bool {
-		return strings.Contains(errorMessage, mapping.originalError)
-	}); ok {
-		return mapping.newError, true
-	}
-
-	return "", false
-}
-
-func TailLogs() {
-	logFilePath, err := config.LogPath()
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	fmt.Printf("Tailing log file %s\n\n", logFilePath)
-
-	opts := humanlog.DefaultOptions
-	opts.Truncates = false
-
-	_, err = os.Stat(logFilePath)
-	if err != nil {
-		if os.IsNotExist(err) {
-			log.Fatal("Log file does not exist. Run `lazygit --debug` first to create the log file")
-		}
-		log.Fatal(err)
-	}
-
-	TailLogsForPlatform(logFilePath, opts)
-}

pkg/app/daemon/daemon.go

@@ -0,0 +1,107 @@
+package daemon
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/jesseduffield/lazygit/pkg/common"
+	"github.com/jesseduffield/lazygit/pkg/env"
+)
+
+// Sometimes lazygit will be invoked in daemon mode from a parent lazygit process.
+// We do this when git lets us supply a program to run within a git command.
+// For example, if we want to ensure that a git command doesn't hang due to
+// waiting for an editor to save a commit message, we can tell git to invoke lazygit
+// as the editor via 'GIT_EDITOR=lazygit', and use the env var
+// 'LAZYGIT_DAEMON_KIND=EXIT_IMMEDIATELY' to specify that we want to run lazygit
+// as a daemon which simply exits immediately. Any additional arguments we want
+// to pass to a daemon can be done via other env vars.
+
+type DaemonKind string
+
+const (
+	InteractiveRebase DaemonKind = "INTERACTIVE_REBASE"
+	ExitImmediately   DaemonKind = "EXIT_IMMEDIATELY"
+)
+
+const (
+	DaemonKindEnvKey string = "LAZYGIT_DAEMON_KIND"
+	RebaseTODOEnvKey string = "LAZYGIT_REBASE_TODO"
+)
+
+type Daemon interface {
+	Run() error
+}
+
+func Handle(common *common.Common) {
+	d := getDaemon(common)
+	if d == nil {
+		return
+	}
+
+	if err := d.Run(); err != nil {
+		log.Fatal(err)
+	}
+
+	os.Exit(0)
+}
+
+func InDaemonMode() bool {
+	return getDaemonKind() != ""
+}
+
+func getDaemon(common *common.Common) Daemon {
+	switch getDaemonKind() {
+	case InteractiveRebase:
+		return &rebaseDaemon{c: common}
+	case ExitImmediately:
+		return &exitImmediatelyDaemon{c: common}
+	}
+
+	return nil
+}
+
+func getDaemonKind() DaemonKind {
+	return DaemonKind(os.Getenv(DaemonKindEnvKey))
+}
+
+type rebaseDaemon struct {
+	c *common.Common
+}
+
+func (self *rebaseDaemon) Run() error {
+	self.c.Log.Info("Lazygit invoked as interactive rebase demon")
+	self.c.Log.Info("args: ", os.Args)
+
+	if strings.HasSuffix(os.Args[1], "git-rebase-todo") {
+		if err := ioutil.WriteFile(os.Args[1], []byte(os.Getenv(RebaseTODOEnvKey)), 0o644); err != nil {
+			return err
+		}
+	} else if strings.HasSuffix(os.Args[1], filepath.Join(gitDir(), "COMMIT_EDITMSG")) { // TODO: test
+		// if we are rebasing and squashing, we'll see a COMMIT_EDITMSG
+		// but in this case we don't need to edit it, so we'll just return
+	} else {
+		self.c.Log.Info("Lazygit demon did not match on any use cases")
+	}
+
+	return nil
+}
+
+func gitDir() string {
+	dir := env.GetGitDirEnv()
+	if dir == "" {
+		return ".git"
+	}
+	return dir
+}
+
+type exitImmediatelyDaemon struct {
+	c *common.Common
+}
+
+func (self *exitImmediatelyDaemon) Run() error {
+	return nil
+}

pkg/app/errors.go

@@ -0,0 +1,39 @@
+package app
+
+import (
+	"strings"
+
+	"github.com/jesseduffield/generics/slices"
+	"github.com/jesseduffield/lazygit/pkg/i18n"
+)
+
+type errorMapping struct {
+	originalError string
+	newError      string
+}
+
+// knownError takes an error and tells us whether it's an error that we know about where we can print a nicely formatted version of it rather than panicking with a stack trace
+func knownError(tr *i18n.TranslationSet, err error) (string, bool) {
+	errorMessage := err.Error()
+
+	knownErrorMessages := []string{tr.MinGitVersionError}
+
+	if slices.Contains(knownErrorMessages, errorMessage) {
+		return errorMessage, true
+	}
+
+	mappings := []errorMapping{
+		{
+			originalError: "fatal: not a git repository",
+			newError:      tr.NotARepository,
+		},
+	}
+
+	if mapping, ok := slices.Find(mappings, func(mapping errorMapping) bool {
+		return strings.Contains(errorMessage, mapping.originalError)
+	}); ok {
+		return mapping.newError, true
+	}
+
+	return "", false
+}

pkg/app/logging.go

@@ -1,31 +1,61 @@
-//go:build !windows
-// +build !windows
-
 package app
 
 import (
+	"io/ioutil"
 	"log"
 	"os"
 
-	"github.com/aybabtme/humanlog"
-	"github.com/jesseduffield/lazygit/pkg/secureexec"
+	"github.com/jesseduffield/lazygit/pkg/config"
+	"github.com/sirupsen/logrus"
 )
 
-func TailLogsForPlatform(logFilePath string, opts *humanlog.HandlerOptions) {
-	cmd := secureexec.Command("tail", "-f", logFilePath)
-
-	stdout, _ := cmd.StdoutPipe()
-	if err := cmd.Start(); err != nil {
-		log.Fatal(err)
+func newLogger(config config.AppConfigurer) *logrus.Entry {
+	var log *logrus.Logger
+	if config.GetDebug() || os.Getenv("DEBUG") == "TRUE" {
+		log = newDevelopmentLogger()
+	} else {
+		log = newProductionLogger()
 	}
 
-	if err := humanlog.Scanner(stdout, os.Stdout, opts); err != nil {
-		log.Fatal(err)
-	}
+	// highly recommended: tail -f development.log | humanlog
+	// https://github.com/aybabtme/humanlog
+	log.Formatter = &logrus.JSONFormatter{}
 
-	if err := cmd.Wait(); err != nil {
-		log.Fatal(err)
-	}
-
-	os.Exit(0)
+	return log.WithFields(logrus.Fields{
+		"debug":     config.GetDebug(),
+		"version":   config.GetVersion(),
+		"commit":    config.GetCommit(),
+		"buildDate": config.GetBuildDate(),
+	})
+}
+
+func newProductionLogger() *logrus.Logger {
+	log := logrus.New()
+	log.Out = ioutil.Discard
+	log.SetLevel(logrus.ErrorLevel)
+	return log
+}
+
+func newDevelopmentLogger() *logrus.Logger {
+	logger := logrus.New()
+	logger.SetLevel(getLogLevel())
+	logPath, err := config.LogPath()
+	if err != nil {
+		log.Fatal(err)
+	}
+	file, err := os.OpenFile(logPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o666)
+	if err != nil {
+		log.Fatalf("Unable to log to log file: %v", err)
+	}
+	logger.SetOutput(file)
+	return logger
+}
+
+func getLogLevel() logrus.Level {
+	strLevel := os.Getenv("LOG_LEVEL")
+	level, err := logrus.ParseLevel(strLevel)
+	if err != nil {
+		return logrus.DebugLevel
+	}
+	return level
 }

pkg/cheatsheet/generate.go

@@ -55,7 +55,11 @@ func generateAtDir(cheatsheetDir string) {
 
 	for lang := range translationSetsByLang {
 		mConfig.GetUserConfig().Gui.Language = lang
-		mApp, _ := app.NewApp(mConfig)
+		common, err := app.NewCommon(mConfig)
+		if err != nil {
+			log.Fatal(err)
+		}
+		mApp, _ := app.NewApp(mConfig, common)
 		path := cheatsheetDir + "/Keybindings_" + lang + ".md"
 		file, err := os.Create(path)
 		if err != nil {

pkg/commands/git_commands/rebase.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/go-errors/errors"
 	"github.com/jesseduffield/generics/slices"
+	"github.com/jesseduffield/lazygit/pkg/app/daemon"
 	"github.com/jesseduffield/lazygit/pkg/commands/models"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
 )
@@ -109,8 +110,8 @@ func (self *RebaseCommands) PrepareInteractiveRebaseCommand(baseSha string, todo
 	}
 
 	cmdObj.AddEnvVars(
-		"LAZYGIT_CLIENT_COMMAND=INTERACTIVE_REBASE",
-		"LAZYGIT_REBASE_TODO="+todo,
+		daemon.DaemonKindEnvKey+"="+string(daemon.InteractiveRebase),
+		daemon.RebaseTODOEnvKey+"="+todo,
 		"DEBUG="+debug,
 		"LANG=en_US.UTF-8",   // Force using EN as language
 		"LC_ALL=en_US.UTF-8", // Force using EN as language
@@ -297,7 +298,7 @@ func (self *RebaseCommands) runSkipEditorCommand(cmdObj oscommands.ICmdObj) erro
 	lazyGitPath := oscommands.GetLazygitPath()
 	return cmdObj.
 		AddEnvVars(
-			"LAZYGIT_CLIENT_COMMAND=EXIT_IMMEDIATELY",
+			daemon.DaemonKindEnvKey+"="+string(daemon.ExitImmediately),
 			"GIT_EDITOR="+lazyGitPath,
 			"EDITOR="+lazyGitPath,
 			"VISUAL="+lazyGitPath,

pkg/commands/git_commands/rebase_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/go-errors/errors"
+	"github.com/jesseduffield/lazygit/pkg/app/daemon"
 	"github.com/jesseduffield/lazygit/pkg/commands/git_config"
 	"github.com/jesseduffield/lazygit/pkg/commands/models"
 	"github.com/jesseduffield/lazygit/pkg/commands/oscommands"
@@ -61,7 +62,7 @@ func TestRebaseSkipEditorCommand(t *testing.T) {
 			`^VISUAL=.*$`,
 			`^EDITOR=.*$`,
 			`^GIT_EDITOR=.*$`,
-			"^LAZYGIT_CLIENT_COMMAND=EXIT_IMMEDIATELY$",
+			"^" + daemon.DaemonKindEnvKey + "=" + string(daemon.ExitImmediately) + "$",
 		} {
 			regexStr := regexStr
 			foundMatch := lo.ContainsBy(envVars, func(envVar string) bool {

pkg/env/env.go

@@ -1,6 +1,10 @@
 package env
 
-import "os"
+import (
+	"os"
+)
+
+// This package encapsulates accessing/mutating the ENV of the program.
 
 func GetGitDirEnv() string {
 	return os.Getenv("GIT_DIR")

pkg/logs/logs.go

@@ -0,0 +1,34 @@
+package logs
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/aybabtme/humanlog"
+	"github.com/jesseduffield/lazygit/pkg/config"
+)
+
+// TailLogs lets us run `lazygit --logs` to print the logs produced by other lazygit processes.
+// This makes for easier debugging.
+func TailLogs() {
+	logFilePath, err := config.LogPath()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("Tailing log file %s\n\n", logFilePath)
+
+	opts := humanlog.DefaultOptions
+	opts.Truncates = false
+
+	_, err = os.Stat(logFilePath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			log.Fatal("Log file does not exist. Run `lazygit --debug` first to create the log file")
+		}
+		log.Fatal(err)
+	}
+
+	TailLogsForPlatform(logFilePath, opts)
+}

pkg/logs/logs_default.go

@@ -0,0 +1,31 @@
+//go:build !windows
+// +build !windows
+
+package logs
+
+import (
+	"log"
+	"os"
+
+	"github.com/aybabtme/humanlog"
+	"github.com/jesseduffield/lazygit/pkg/secureexec"
+)
+
+func TailLogsForPlatform(logFilePath string, opts *humanlog.HandlerOptions) {
+	cmd := secureexec.Command("tail", "-f", logFilePath)
+
+	stdout, _ := cmd.StdoutPipe()
+	if err := cmd.Start(); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := humanlog.Scanner(stdout, os.Stdout, opts); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := cmd.Wait(); err != nil {
+		log.Fatal(err)
+	}
+
+	os.Exit(0)
+}

pkg/logs/logs_windows.go

@@ -1,7 +1,7 @@
 //go:build windows
 // +build windows
 
-package app
+package logs
 
 import (
 	"bufio"