adds tests for reload

cmd/agent.go

@@ -20,8 +20,7 @@ const pidDir = "/tmp/tplagent"
 const pidFilename = "agent.pid"
 
 func startAgent(ctx context.Context, configFilePath string) error {
-	pid := os.Getpid()
-	writePID(pid)
+	writePID(filepath.Join(pidDir, pidFilename))
 	defer func() {
 		_ = os.Remove(fmt.Sprintf("%s/%s", pidDir, pidFilename))
 	}()
@@ -78,11 +77,11 @@ func newLogger(fmt string, level slog.Level) *slog.Logger {
 
 }
 
-func writePID(pid int) {
+func writePID(path string) {
+	pid := os.Getpid()
 	if err := os.MkdirAll(pidDir, 0755); err != nil {
 		return
 	}
-	fullPath := filepath.Join(pidDir, pidFilename)
 	bs := []byte(strconv.Itoa(pid))
-	_ = os.WriteFile(fullPath, bs, 0755)
+	_ = os.WriteFile(path, bs, 0755)
 }

cmd/cli.go

@@ -7,8 +7,12 @@ import (
 	"fmt"
 	"github.com/shubhang93/tplagent/internal/config"
 	"io"
+	"os"
+	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
+	"syscall"
 )
 
 const usage = `usage:
@@ -69,9 +73,34 @@ Go Runtime: %s`
 		if err != nil {
 			return err
 		}
+	case "reload":
+		pidFilePath := filepath.Join(pidDir, pidFilename)
+		return reload(pidFilePath)
 	default:
 		return errors.New(usage)
 	}
 	return nil
+}
+
+func reload(pidFilePath string) error {
+	contents, err := os.ReadFile(pidFilePath)
+	if err != nil {
+		return err
+	}
+
+	pid, err := strconv.Atoi(string(contents))
+	if err != nil {
+		return fmt.Errorf("error converting PID:%w", err)
+	}
 
+	proc, err := os.FindProcess(pid)
+	if err != nil {
+		return fmt.Errorf("proc find err:%w", err)
+	}
+
+	err = proc.Signal(syscall.SIGHUP)
+	if err != nil {
+		return fmt.Errorf("sig send err:%w", err)
+	}
+	return nil
 }

cmd/cli_test.go

@@ -12,7 +12,9 @@ import (
 	"github.com/shubhang93/tplagent/internal/fatal"
 	"log/slog"
 	"os"
+	"os/signal"
 	"strings"
+	"syscall"
 	"testing"
 	"time"
 )
@@ -206,4 +208,30 @@ written from exec
 		}
 
 	})
+
+	t.Run("test reload", func(t *testing.T) {
+		tmp := t.TempDir()
+		sighup, cancel := signal.NotifyContext(context.Background(), syscall.SIGHUP)
+		defer cancel()
+
+		sighupReceived := make(chan bool, 1)
+		go func() {
+			<-sighup.Done()
+			sighupReceived <- true
+		}()
+
+		pidPath := tmp + "/agent.pid"
+
+		writePID(pidPath)
+
+		err := reload(pidPath)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+
+		if rcvd := <-sighupReceived; !rcvd {
+			t.Errorf("SIGHUP not received")
+		}
+	})
 }