Allow logging targets to be configured to receive minio (#8347)

specific errors, `application` errors or `all` by default.

console logging on server by default lists all logs -
enhance admin console API to accept `type` as query parameter to
subscribe to application/minio logs.

cmd/logger/logger.go

@@ -273,36 +273,53 @@ func hashString(input string) string {
 	return hex.EncodeToString(checksum)
 }
 
+// Kind specifies the kind of error log
+type Kind string
+
+const (
+	// Minio errors
+	Minio Kind = "MINIO"
+	// Application errors
+	Application Kind = "APPLICATION"
+	// All errors
+	All Kind = "ALL"
+)
+
 // LogAlwaysIf prints a detailed error message during
 // the execution of the server.
-func LogAlwaysIf(ctx context.Context, err error) {
+func LogAlwaysIf(ctx context.Context, err error, errKind ...interface{}) {
 	if err == nil {
 		return
 	}
 
-	logIf(ctx, err)
+	logIf(ctx, err, errKind...)
 }
 
 // LogIf prints a detailed error message during
 // the execution of the server, if it is not an
 // ignored error.
-func LogIf(ctx context.Context, err error) {
+func LogIf(ctx context.Context, err error, errKind ...interface{}) {
 	if err == nil {
 		return
 	}
 
 	if err.Error() != diskNotFoundError {
-		logIf(ctx, err)
+		logIf(ctx, err, errKind...)
 	}
 }
 
 // logIf prints a detailed error message during
 // the execution of the server.
-func logIf(ctx context.Context, err error) {
+func logIf(ctx context.Context, err error, errKind ...interface{}) {
 	if Disable {
 		return
 	}
-
+	logKind := string(Minio)
+	if len(errKind) > 0 {
+		if ek, ok := errKind[0].(Kind); ok {
+			logKind = string(ek)
+		}
+	}
 	req := GetReqInfo(ctx)
 
 	if req == nil {
@@ -330,6 +347,7 @@ func logIf(ctx context.Context, err error) {
 	entry := log.Entry{
 		DeploymentID: req.DeploymentID,
 		Level:        ErrorLvl.String(),
+		LogKind:      logKind,
 		RemoteHost:   req.RemoteHost,
 		Host:         req.Host,
 		RequestID:    req.RequestID,
@@ -359,7 +377,7 @@ func logIf(ctx context.Context, err error) {
 
 	// Iterate over all logger targets to send the log entry
 	for _, t := range Targets {
-		t.Send(entry)
+		t.Send(entry, entry.LogKind)
 	}
 }
 
@@ -368,9 +386,9 @@ var ErrCritical struct{}
 
 // CriticalIf logs the provided error on the console. It fails the
 // current go-routine by causing a `panic(ErrCritical)`.
-func CriticalIf(ctx context.Context, err error) {
+func CriticalIf(ctx context.Context, err error, errKind ...interface{}) {
 	if err != nil {
-		LogIf(ctx, err)
+		LogIf(ctx, err, errKind...)
 		panic(ErrCritical)
 	}
 }