WIP: logging in the background process

service/serve.go

@@ -29,6 +29,9 @@ import (
 
 	pb "gitea.suyono.dev/suyono/go-agent/proto"
 	"gitea.suyono.dev/suyono/go-agent/storage"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/diode"
+	"github.com/rs/zerolog/log"
 	"google.golang.org/grpc"
 	"google.golang.org/protobuf/types/known/emptypb"
 )
@@ -82,6 +85,7 @@ func (s *server) Get(ctx context.Context, req *pb.CacheGetRequest) (*pb.CacheVal
 func (s *server) Set(ctx context.Context, req *pb.CacheSetRequest) (*pb.SetStatus, error) {
 	err := s.stor.Set(req.GetKey(), req.GetValue())
 	if err != nil {
+		log.Error().Err(err).Caller().Msg("failed to set cache")
 		return nil, err
 	}
 	return &pb.SetStatus{
@@ -96,42 +100,53 @@ func (s *server) Shutdown(context.Context, *emptypb.Empty) (*emptypb.Empty, erro
 	return &emptypb.Empty{}, nil
 }
 
-func GetDaemonLogPath() (string, error) {
-	// The child process of the main program should call this function and set up the logging infrastructure
-	envVal, ok := os.LookupEnv(goAgentDaemonLogPath)
-	if !ok {
-		return "", fmt.Errorf("programming issue: parent process did not set log path")
-	}
-	return envVal, nil
-}
-
 func ExecBackground(opt Option) (BgProcFlag, error) {
 	var (
-		cmd    *exec.Cmd
-		ok     bool
-		envVal string
+		cmd     *exec.Cmd
+		envVal  string
+		logPath string
+		err     error
+		f       *os.File
 	)
 
 	args := opt.ExecArgs()
-	envVal, ok = os.LookupEnv(goAgentDaemonEnvFlag)
-	if !opt.Background() || len(args) == 0 || (envVal == "1" && ok) {
+	envVal = os.Getenv(goAgentDaemonEnvFlag)
+	if !opt.Background() || len(args) == 0 || envVal == "1" {
+		if envVal == "1" {
+			logPath = os.Getenv(goAgentDaemonLogPath)
+			if logPath == "" {
+				panic(fmt.Errorf("cannot start background process without log path"))
+			}
+
+			if f, err = os.OpenFile(logPath, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0600); err != nil {
+				panic(fmt.Errorf("opening log file: %w", err))
+			}
+
+			log.Logger = zerolog.New(diode.NewWriter(f, 1000, 10*time.Millisecond, func(missed int) {
+				fmt.Printf("Logger Dropped %d messages", missed)
+			}))
+		}
+
 		return child, nil
 	}
 
+	if opt.ExecLogPath() == "" {
+		return parent, fmt.Errorf("cannot start background process without log path")
+	}
+
 	if len(args) > 1 {
 		cmd = exec.Command(args[0], args[1:]...)
 	} else {
 		cmd = exec.Command(args[0])
 	}
-	cmd.Env = append(os.Environ(), fmt.Sprintf("%s=1", goAgentDaemonEnvFlag))
-	if opt.ExecLogPath() != "" {
-		cmd.Env = append(cmd.Env, fmt.Sprintf("%s=%s", goAgentDaemonLogPath, opt.ExecLogPath()))
-	}
-	cmd.Env = append(cmd.Env, opt.ExecEnv()...)
+	cmd.Env = append(os.Environ(), opt.ExecEnv()...)
+	cmd.Env = append(cmd.Env,
+		fmt.Sprintf("%s=1", goAgentDaemonEnvFlag),
+		fmt.Sprintf("%s=%s", goAgentDaemonLogPath, opt.ExecLogPath()))
 	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
 	cmd.Stdin, cmd.Stdout, cmd.Stderr = nil, nil, nil
 
-	if err := cmd.Start(); err != nil {
+	if err = cmd.Start(); err != nil {
 		return parent, err
 	}