Cleanup ui-errors and print proper error messages (#8068)

* Cleanup ui-errors and print proper error messages

Change HELP to HINT instead, handle more error
cases when starting up MinIO. One such is related
to #8048

* Apply suggestions from code review

cmd/common-main.go

@@ -61,6 +61,9 @@ func verifyObjectLayerFeatures(name string, objAPI ObjectLayer) {
 func checkUpdate(mode string) {
 	// Its OK to ignore any errors during doUpdate() here.
 	if updateMsg, _, currentReleaseTime, latestReleaseTime, err := getUpdateInfo(2*time.Second, mode); err == nil {
+		if updateMsg == "" {
+			return
+		}
 		if globalInplaceUpdateDisabled {
 			logger.StartupMessage(updateMsg)
 		} else {

cmd/server-main.go

@@ -1,5 +1,5 @@
 /*
- * MinIO Cloud Storage, (C) 2015, 2016, 2017, 2018 MinIO, Inc.
+ * MinIO Cloud Storage, (C) 2015-2019 MinIO, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -377,7 +377,7 @@ func serverMain(ctx *cli.Context) {
 
 	// Initialize notification system.
 	if err = globalNotificationSys.Init(newObject); err != nil {
-		logger.LogIf(context.Background(), err)
+		logger.Fatal(err, "Unable to initialize notification system")
 	}
 
 	// Verify if object layer supports

cmd/signals.go

@@ -1,5 +1,5 @@
 /*
- * MinIO Cloud Storage, (C) 2015, 2016, 2017, 2018 MinIO, Inc.
+ * MinIO Cloud Storage, (C) 2015-2019 MinIO, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,13 +26,13 @@ import (
 
 func handleSignals() {
 	// Custom exit function
-	exit := func(state bool) {
+	exit := func(success bool) {
 		// If global profiler is set stop before we exit.
 		if globalProfiler != nil {
 			globalProfiler.Stop()
 		}
 
-		if state {
+		if success {
 			os.Exit(0)
 		}
 
@@ -66,13 +66,13 @@ func handleSignals() {
 	for {
 		select {
 		case err := <-globalHTTPServerErrorCh:
-			logger.LogIf(context.Background(), err)
-			var oerr error
 			if objAPI := newObjectLayerFn(); objAPI != nil {
-				oerr = objAPI.Shutdown(context.Background())
+				objAPI.Shutdown(context.Background())
 			}
-
+			if err != nil {
-			exit(err == nil && oerr == nil)
+				logger.Fatal(err, "Unable to start MinIO server")
+			}
+			exit(true)
 		case osSignal := <-globalOSSignalCh:
 			logger.Info("Exiting on signal: %s", strings.ToUpper(osSignal.String()))
 			exit(stopProcess())

cmd/ui-errors-utils.go

@@ -1,5 +1,5 @@
 /*
- * MinIO Cloud Storage, (C) 2018 MinIO, Inc.
+ * MinIO Cloud Storage, (C) 2018-2019 MinIO, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import (
 	"io"
 	"net"
 	"os"
+	"syscall"
 )
 
 // uiErr is a structure which contains all information
@@ -30,7 +31,7 @@ type uiErr struct {
 	msg    string
 	detail string
 	action string
-	help   string
+	hint   string
 }
 
 // Return the error message
@@ -47,7 +48,7 @@ func (u uiErr) Msg(m string, args ...interface{}) uiErr {
 		msg:    fmt.Sprintf(m, args...),
 		detail: u.detail,
 		action: u.action,
-		help:   u.help,
+		hint:   u.hint,
 	}
 }
 
@@ -56,12 +57,12 @@ type uiErrFn func(err error) uiErr
 // Create a UI error generator, this is needed to simplify
 // the update of the detailed error message in several places
 // in MinIO code
-func newUIErrFn(msg, action, help string) uiErrFn {
+func newUIErrFn(msg, action, hint string) uiErrFn {
 	return func(err error) uiErr {
 		u := uiErr{
 			msg:    msg,
 			action: action,
-			help:   help,
+			hint:   hint,
 		}
 		if err != nil {
 			u.detail = err.Error()
@@ -82,8 +83,13 @@ func errorToUIErr(err error) uiErr {
 	switch e := err.(type) {
 	case *net.OpError:
 		if e.Op == "listen" {
-			return uiErrPortAlreadyInUse(e).Msg("Port " + e.Addr.String() + " is already in use")
+			if oe, ok := e.Err.(*os.SyscallError); ok {
-
+				if oe.Err == syscall.EADDRINUSE {
+					return uiErrPortAlreadyInUse(e).Msg("Specified port '" + e.Addr.String() + "' is already in use")
+				} else if oe.Err == syscall.EACCES {
+					return uiErrPortAccess(e).Msg("Insufficient permissions to use specified port '" + e.Addr.String() + "'")
+				}
+			}
 		}
 	case *os.PathError:
 		if os.IsPermission(e) {
@@ -117,19 +123,19 @@ func fmtError(introMsg string, err error, jsonFlag bool) string {
 	// Pretty print error message
 	introMsg += ": "
 	if uiErr.msg != "" {
-		introMsg += colorBold(uiErr.msg + ".")
+		introMsg += colorBold(uiErr.msg)
 	} else {
-		introMsg += colorBold(err.Error() + ".")
+		introMsg += colorBold(err.Error())
 	}
 	renderedTxt += colorRed(introMsg) + "\n"
 	// Add action message
 	if uiErr.action != "" {
-		renderedTxt += "> " + colorBgYellow(colorBlack(uiErr.action+".")) + "\n"
+		renderedTxt += "> " + colorBgYellow(colorBlack(uiErr.action)) + "\n"
 	}
-	// Add help
+	// Add hint
-	if uiErr.help != "" {
+	if uiErr.hint != "" {
-		renderedTxt += colorBold("HELP:") + "\n"
+		renderedTxt += colorBold("HINT:") + "\n"
-		renderedTxt += "  " + uiErr.help
+		renderedTxt += "  " + uiErr.hint
 	}
 	return renderedTxt
 }

cmd/ui-errors.go

@@ -1,5 +1,5 @@
 /*
- * MinIO Cloud Storage, (C) 2018 MinIO, Inc.
+ * MinIO Cloud Storage, (C) 2018-2019 MinIO, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,13 +32,13 @@ var (
 	uiErrInvalidDomainValue = newUIErrFn(
 		"Invalid domain value",
 		"Please check the passed value",
-		"Domain can only accept DNS compatible values.",
+		"Domain can only accept DNS compatible values",
 	)
 
 	uiErrInvalidErasureSetSize = newUIErrFn(
 		"Invalid erasure set size",
 		"Please check the passed value",
-		"Erasure set can only accept any of [4, 6, 8, 10, 12, 14, 16] values.",
+		"Erasure set can only accept any of [4, 6, 8, 10, 12, 14, 16] values",
 	)
 
 	uiErrInvalidWormValue = newUIErrFn(
@@ -62,32 +62,32 @@ var (
 	uiErrInvalidCacheExpiryValue = newUIErrFn(
 		"Invalid cache expiry value",
 		"Please check the passed value",
-		"MINIO_CACHE_EXPIRY: Valid cache expiry duration is in days.",
+		"MINIO_CACHE_EXPIRY: Valid cache expiry duration is in days",
 	)
 
 	uiErrInvalidCacheMaxUse = newUIErrFn(
 		"Invalid cache max-use value",
 		"Please check the passed value",
-		"MINIO_CACHE_MAXUSE: Valid cache max-use value between 0-100.",
+		"MINIO_CACHE_MAXUSE: Valid cache max-use value between 0-100",
 	)
 
 	uiErrInvalidCredentials = newUIErrFn(
 		"Invalid credentials",
 		"Please provide correct credentials",
 		`Access key length should be between minimum 3 characters in length.
-Secret key should be in between 8 and 40 characters.`,
+Secret key should be in between 8 and 40 characters`,
 	)
 
 	uiErrEnvCredentialsMissingGateway = newUIErrFn(
 		"Credentials missing",
 		"Please set your credentials in the environment",
-		`In Gateway mode, access and secret keys should be specified via environment variables MINIO_ACCESS_KEY and MINIO_SECRET_KEY respectively.`,
+		`In Gateway mode, access and secret keys should be specified via environment variables MINIO_ACCESS_KEY and MINIO_SECRET_KEY respectively`,
 	)
 
 	uiErrEnvCredentialsMissingDistributed = newUIErrFn(
 		"Credentials missing",
 		"Please set your credentials in the environment",
-		`In distributed server mode, access and secret keys should be specified via environment variables MINIO_ACCESS_KEY and MINIO_SECRET_KEY respectively.`,
+		`In distributed server mode, access and secret keys should be specified via environment variables MINIO_ACCESS_KEY and MINIO_SECRET_KEY respectively`,
 	)
 
 	uiErrInvalidErasureEndpoints = newUIErrFn(
@@ -105,9 +105,9 @@ Secret key should be in between 8 and 40 characters.`,
 	uiErrStorageClassValue = newUIErrFn(
 		"Invalid storage class value",
 		"Please check the value",
-		`MINIO_STORAGE_CLASS_STANDARD: Format "EC:<Default_Parity_Standard_Class>" (e.g. "EC:3"). This sets the number of parity disks for MinIO server in Standard mode. Objects are stored in Standard mode, if storage class is not defined in Put request.
+		`MINIO_STORAGE_CLASS_STANDARD: Format "EC:<Default_Parity_Standard_Class>" (e.g. "EC:3"). This sets the number of parity disks for MinIO server in Standard mode. Objects are stored in Standard mode, if storage class is not defined in Put request
-MINIO_STORAGE_CLASS_RRS: Format "EC:<Default_Parity_Reduced_Redundancy_Class>" (e.g. "EC:3"). This sets the number of parity disks for MinIO server in Reduced Redundancy mode. Objects are stored in Reduced Redundancy mode, if Put request specifies RRS storage class.
+MINIO_STORAGE_CLASS_RRS: Format "EC:<Default_Parity_Reduced_Redundancy_Class>" (e.g. "EC:3"). This sets the number of parity disks for MinIO server in Reduced Redundancy mode. Objects are stored in Reduced Redundancy mode, if Put request specifies RRS storage class
-Refer to the link https://github.com/minio/minio/tree/master/docs/erasure/storage-class for more information.`,
+Refer to the link https://github.com/minio/minio/tree/master/docs/erasure/storage-class for more information`,
 	)
 
 	uiErrUnexpectedBackendVersion = newUIErrFn(
@@ -128,7 +128,7 @@ Refer to the link https://github.com/minio/minio/tree/master/docs/erasure/storag
 	uiErrInvalidFSEndpoint = newUIErrFn(
 		"Invalid endpoint for standalone FS mode",
 		"Please check the FS endpoint",
-		`FS mode requires only one writable disk path.
+		`FS mode requires only one writable disk path
 Example 1:
    $ minio server /data/minio/`,
 	)
@@ -136,7 +136,7 @@ Example 1:
 	uiErrUnableToWriteInBackend = newUIErrFn(
 		"Unable to write to the backend",
 		"Please ensure MinIO binary has write permissions for the backend",
-		"",
+		`Verify if MinIO binary is running as the same user who has write permissions for the backend`,
 	)
 
 	uiErrPortAlreadyInUse = newUIErrFn(
@@ -145,6 +145,12 @@ Example 1:
 		"",
 	)
 
+	uiErrPortAccess = newUIErrFn(
+		"Unable to use specified port",
+		"Please ensure MinIO binary has 'cap_net_bind_service=+ep' permissions",
+		`Use 'sudo setcap cap_net_bind_service=+ep /path/to/minio' to provide sufficient permissions`,
+	)
+
 	uiErrNoPermissionsToAccessDirFiles = newUIErrFn(
 		"Missing permissions to access the specified path",
 		"Please ensure the specified path can be accessed",
@@ -154,7 +160,7 @@ Example 1:
 	uiErrSSLUnexpectedError = newUIErrFn(
 		"Invalid TLS certificate",
 		"Please check the content of your certificate data",
-		`Only PEM (x.509) format is accepted as valid public & private certificates.`,
+		`Only PEM (x.509) format is accepted as valid public & private certificates`,
 	)
 
 	uiErrSSLUnexpectedData = newUIErrFn(
@@ -171,8 +177,8 @@ Example 1:
 
 	uiErrNoCertsAndHTTPSEndpoints = newUIErrFn(
 		"HTTPS specified in endpoints, but no TLS certificate is found on the local machine",
-		"Please add a certificate or switch to HTTP.",
+		"Please add TLS certificate or use HTTP endpoints only",
-		"Refer to https://docs.min.io/docs/how-to-secure-access-to-minio-server-with-tls for information about how to load a TLS certificate in your server.",
+		"Refer to https://docs.min.io/docs/how-to-secure-access-to-minio-server-with-tls for information about how to load a TLS certificate in your server",
 	)
 
 	uiErrCertsAndHTTPEndpoints = newUIErrFn(