fix: Remove combined flags file on restart

launchpad/pkg/filewatcher.go

@@ -7,7 +7,23 @@ import (
 	"sync"
 )
 
-var changeFlagLock sync.Mutex
+var (
+	changeFlagLock sync.Mutex
+	workLock       sync.Mutex
+	isPaused       = false
+)
+
+func PauseFileWatcher() {
+	workLock.Lock()
+	defer workLock.Unlock()
+	isPaused = true
+}
+
+func ContinueFileWatcher() {
+	workLock.Lock()
+	defer workLock.Unlock()
+	isPaused = false
+}
 
 func StartFileWatcher() error {
 	watcher, err := fsnotify.NewWatcher()
@@ -24,9 +40,17 @@ func StartFileWatcher() error {
 					return
 				}
 				if event.Op&(fsnotify.Create|fsnotify.Write|fsnotify.Remove) != 0 {
+					workLock.Lock()
+					if isPaused {
+						workLock.Unlock()
+						fmt.Printf("%v config changed, but file watcher is paused \n", event.Name)
+						return
+					}
 					fmt.Printf("%v config changed, regenerating JSON...\n", event.Name)
 					if err := CombineJSONFiles(InputDir); err != nil {
 						fmt.Printf("Error combining JSON files: %v\n", err)
+						workLock.Unlock()
+						return
 					}
 					if strings.HasSuffix(event.Name, "changing-flag.json") {
 						changeFlagLock.Lock()
@@ -36,6 +60,8 @@ func StartFileWatcher() error {
 						changeFlagUpdateListeners = nil
 						changeFlagLock.Unlock()
 					}
+
+					workLock.Unlock()
 				}
 			case err, ok := <-watcher.Errors:
 				if !ok {

launchpad/pkg/flagd.go

@@ -3,8 +3,10 @@ package flagd
 import (
 	"bufio"
 	"context"
+	"errors"
 	"fmt"
 	"io"
+	"os"
 	"os/exec"
 	"strings"
 	"sync"
@@ -18,6 +20,21 @@ var (
 	restartCancelFunc context.CancelFunc // Stores the cancel function for delayed restarts
 )
 
+func ensureStartConditions() {
+	if _, err := os.Stat(OutputFile); errors.Is(err, os.ErrNotExist) {
+		err := CombineJSONFiles(InputDir)
+		if err != nil {
+			fmt.Printf("Error combining JSON files on flagd start: %v\n", err)
+		}
+	}
+	ContinueFileWatcher()
+}
+
+func deleteCombinedFlagsFile() {
+	// if we cannot delete it, we can assume it did not exist in the first place, so we can ignore this error
+	_ = os.Remove(OutputFile)
+}
+
 func RestartFlagd(seconds int) {
 	flagdLock.Lock()
 	if restartCancelFunc != nil {
@@ -28,6 +45,8 @@ func RestartFlagd(seconds int) {
 	ctx, cancel := context.WithCancel(context.Background())
 	restartCancelFunc = cancel
 
+	PauseFileWatcher()
+	deleteCombinedFlagsFile()
 	err := stopFlagDWithoutLock()
 	if err != nil {
 		fmt.Printf("Failed to restart flagd: %v\n", err)
@@ -69,6 +88,8 @@ func StartFlagd(config string) error {
 		return err
 	}
 
+	ensureStartConditions()
+
 	configPath := fmt.Sprintf("./configs/%s.json", config)
 
 	flagdCmd = exec.Command("./flagd", "start", "--config", configPath)