Merge pull request #2348 from versity/ben/access-log-stdout

feat: support admin/access logs on standard streams

cmd/versitygw/main.go

@@ -442,13 +442,13 @@ func initFlags() []cli.Flag {
 		},
 		&cli.StringFlag{
 			Name:        "access-log",
-			Usage:       "enable server access logging to specified file",
+			Usage:       "enable server access logging to specified file, stdout, stderr, or - for stdout",
 			EnvVars:     []string{"LOGFILE", "VGW_ACCESS_LOG"},
 			Destination: &accessLog,
 		},
 		&cli.StringFlag{
 			Name:        "admin-access-log",
-			Usage:       "enable admin server access logging to specified file",
+			Usage:       "enable admin server access logging to specified file, stdout, stderr, or - for stdout",
 			EnvVars:     []string{"LOGFILE", "VGW_ADMIN_ACCESS_LOG"},
 			Destination: &adminLogFile,
 		},

cmd/vgwrdma/main.go

@@ -483,13 +483,13 @@ func initFlags() []cli.Flag {
 		},
 		&cli.StringFlag{
 			Name:        "access-log",
-			Usage:       "enable server access logging to specified file",
+			Usage:       "enable server access logging to specified file, stdout, stderr, or - for stdout",
 			EnvVars:     []string{"LOGFILE", "VGW_ACCESS_LOG"},
 			Destination: &accessLog,
 		},
 		&cli.StringFlag{
 			Name:        "admin-access-log",
-			Usage:       "enable admin server access logging to specified file",
+			Usage:       "enable admin server access logging to specified file, stdout, stderr, or - for stdout",
 			EnvVars:     []string{"LOGFILE", "VGW_ADMIN_ACCESS_LOG"},
 			Destination: &adminLogFile,
 		},

embedgw/embedgw.go

@@ -347,14 +347,16 @@ type Config struct {
 	// are independent and can be enabled simultaneously in any combination.
 	// All are optional; omit or leave empty to disable that output.
 
-	// AccessLog is the file path for S3 request access logs in the AWS S3
+	// AccessLog is the file path or stream name (stdout, stderr, or - for
+	// stdout) for S3 request access logs in the AWS S3
 	// access log format. Use absolute paths; relative paths may break if the
 	// server changes its working directory. Empty disables file logging.
 	AccessLog string
 	// LogWebhookURL is an HTTP(S) URL that receives S3 access log entries as
 	// JSON-encoded POST requests. Can be set alongside AccessLog.
 	LogWebhookURL string
-	// AdminLogFile is the file path for admin API request logs.
+	// AdminLogFile is the file path or stream name (stdout, stderr, or - for
+	// stdout) for admin API request logs.
 	AdminLogFile string
 
 	// Metrics

extra/example.conf

@@ -196,18 +196,18 @@ ROOT_SECRET_ACCESS_KEY=
 # Access Logs #
 ###############
 
-# The VGW_ACCESS_LOG option when set will specify the file to log all S3
-# server requests to. This option is optional, and defaults to not logging.
-# It is suggested to use absolute paths for the server log file because the
-# server may chdir into the backend root directory and change locations for
-# relative paths.
+# The VGW_ACCESS_LOG option when set will specify where to log all S3
+# server requests. Set it to a file path, stdout, stderr, or - for stdout.
+# This option is optional, and defaults to not logging. When using a file,
+# it is suggested to use an absolute path because the server may chdir into
+# the backend root directory and change locations for relative paths.
 # The log file format follows the AWS S3 access log format documented in
 # https://docs.aws.amazon.com/AmazonS3/latest/userguide/LogFormat.html.
 #VGW_ACCESS_LOG=
 
-# The VGW_ADMIN_ACCESS_LOG option when set will specify the file to log all
-# admin server requests to. When not set, admin requests are logged to the
-# same file as the S3 server (VGW_ACCESS_LOG) if that is configured.
+# The VGW_ADMIN_ACCESS_LOG option when set will specify where to log all
+# admin server requests. Set it to a file path, stdout, stderr, or - for
+# stdout. This option is optional, and defaults to not logging admin requests.
 #VGW_ADMIN_ACCESS_LOG=
 
 # The VGW_LOG_WEBHOOK_URL option when set will specify the URL to send the

s3log/file.go

@@ -35,24 +35,37 @@ const (
 
 // FileLogger is a local file audit log
 type FileLogger struct {
-	logfile string
-	f       *os.File
-	gotErr  bool
-	mu      sync.Mutex
+	logfile        string
+	f              *os.File
+	standardStream bool
+	gotErr         bool
+	mu             sync.Mutex
 }
 
 var _ AuditLogger = &FileLogger{}
 
 // InitFileLogger initializes audit logs to local file
 func InitFileLogger(logname string) (AuditLogger, error) {
-	f, err := os.OpenFile(logname, os.O_APPEND|os.O_CREATE|os.O_WRONLY, logFileMode)
+	f, standardStream, err := openLogDestination(logname)
 	if err != nil {
 		return nil, fmt.Errorf("open log: %w", err)
 	}
 
 	fmt.Fprintf(f, "log starts %v\n", time.Now())
 
-	return &FileLogger{logfile: logname, f: f}, nil
+	return &FileLogger{logfile: logname, f: f, standardStream: standardStream}, nil
+}
+
+func openLogDestination(logname string) (*os.File, bool, error) {
+	switch strings.ToLower(logname) {
+	case "stdout", "-":
+		return os.Stdout, true, nil
+	case "stderr":
+		return os.Stderr, true, nil
+	default:
+		f, err := os.OpenFile(logname, os.O_APPEND|os.O_CREATE|os.O_WRONLY, logFileMode)
+		return f, false, err
+	}
 }
 
 // Log sends log message to file logger
@@ -222,6 +235,11 @@ func (f *FileLogger) writeLog(lf LogFields) {
 // HangUp closes current logfile handle and opens a new one
 // typically needed for log rotations
 func (f *FileLogger) HangUp() error {
+	if f.standardStream {
+		f.f.WriteString(fmt.Sprintf("log starts %v\n", time.Now()))
+		return nil
+	}
+
 	err := f.f.Close()
 	if err != nil {
 		return fmt.Errorf("close log: %w", err)
@@ -239,5 +257,9 @@ func (f *FileLogger) HangUp() error {
 
 // Shutdown closes logfile handle
 func (f *FileLogger) Shutdown() error {
+	if f.standardStream {
+		return nil
+	}
+
 	return f.f.Close()
 }

s3log/file_admin.go

@@ -34,14 +34,14 @@ var _ AuditLogger = &AdminFileLogger{}
 
 // InitFileLogger initializes audit logs to local file
 func InitAdminFileLogger(logname string) (AuditLogger, error) {
-	f, err := os.OpenFile(logname, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	f, standardStream, err := openLogDestination(logname)
 	if err != nil {
 		return nil, fmt.Errorf("open log: %w", err)
 	}
 
 	f.WriteString(fmt.Sprintf("log starts %v\n", time.Now()))
 
-	return &AdminFileLogger{FileLogger: FileLogger{logfile: logname, f: f}}, nil
+	return &AdminFileLogger{FileLogger: FileLogger{logfile: logname, f: f, standardStream: standardStream}}, nil
 }
 
 // Log sends log message to file logger