[NOD-410] Add log level CLI argument to API server (#503)

* [NOD-410] Add log level CLI argument to API server

* [NOD-410] Add comments

* [NOD-410] Remove pre-allocation of one item

apiserver/config/config.go

@@ -30,6 +30,7 @@ func ActiveConfig() *Config {
 // Config defines the configuration options for the API server.
 type Config struct {
 	LogDir            string `long:"logdir" description:"Directory to log output."`
+	DebugLevel        string `short:"d" long:"debuglevel" description:"Set log level {trace, debug, info, warn, error, critical}"`
 	RPCUser           string `short:"u" long:"rpcuser" description:"RPC username"`
 	RPCPassword       string `short:"P" long:"rpcpass" default-mask:"-" description:"RPC password"`
 	RPCServer         string `short:"s" long:"rpcserver" description:"RPC server to connect to"`
@@ -48,7 +49,7 @@ type Config struct {
 }
 
 // Parse parses the CLI arguments and returns a config struct.
-func Parse() (*Config, error) {
+func Parse() error {
 	activeConfig = &Config{
 		LogDir:     defaultLogDir,
 		DBAddress:  defaultDBAddress,
@@ -57,42 +58,49 @@ func Parse() (*Config, error) {
 	parser := flags.NewParser(activeConfig, flags.PrintErrors|flags.HelpFlag)
 	_, err := parser.Parse()
 	if err != nil {
-		return nil, err
+		return err
 	}
 
 	if !activeConfig.Migrate {
 		if activeConfig.RPCUser == "" {
-			return nil, errors.New("--rpcuser is required if --migrate flag is not used")
+			return errors.New("--rpcuser is required if --migrate flag is not used")
 		}
 		if activeConfig.RPCPassword == "" {
-			return nil, errors.New("--rpcpass is required if --migrate flag is not used")
+			return errors.New("--rpcpass is required if --migrate flag is not used")
 		}
 		if activeConfig.RPCServer == "" {
-			return nil, errors.New("--rpcserver is required if --migrate flag is not used")
+			return errors.New("--rpcserver is required if --migrate flag is not used")
 		}
 	}
 
 	if activeConfig.RPCCert == "" && !activeConfig.DisableTLS {
-		return nil, errors.New("--notls has to be disabled if --cert is used")
+		return errors.New("--notls has to be disabled if --cert is used")
 	}
 
 	if activeConfig.RPCCert != "" && activeConfig.DisableTLS {
-		return nil, errors.New("--cert should be omitted if --notls is used")
+		return errors.New("--cert should be omitted if --notls is used")
 	}
 
 	if (activeConfig.MQTTBrokerAddress != "" || activeConfig.MQTTUser != "" || activeConfig.MQTTPassword != "") &&
 		(activeConfig.MQTTBrokerAddress == "" || activeConfig.MQTTUser == "" || activeConfig.MQTTPassword == "") {
-		return nil, errors.New("--mqttaddress, --mqttuser, and --mqttpass must be passed all together")
+		return errors.New("--mqttaddress, --mqttuser, and --mqttpass must be passed all together")
 	}
 
 	err = activeConfig.ResolveNetwork(parser)
 	if err != nil {
-		return nil, err
+		return err
 	}
 
 	logFile := filepath.Join(activeConfig.LogDir, defaultLogFilename)
 	errLogFile := filepath.Join(activeConfig.LogDir, defaultErrLogFilename)
 	logger.InitLog(logFile, errLogFile)
 
-	return activeConfig, nil
+	if activeConfig.DebugLevel != "" {
+		err := logger.SetLogLevels(activeConfig.DebugLevel)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
 }

apiserver/database/log.go

@@ -4,6 +4,6 @@ import "github.com/daglabs/btcd/util/panics"
 import "github.com/daglabs/btcd/apiserver/logger"
 
 var (
-	log   = logger.BackendLog.Logger("DTBS")
+	log   = logger.Logger("DTBS")
 	spawn = panics.GoroutineWrapperFunc(log, logger.BackendLog)
 )

apiserver/log.go

@@ -6,6 +6,6 @@ import (
 )
 
 var (
-	log   = logger.BackendLog.Logger("APIS")
+	log   = logger.Logger("APIS")
 	spawn = panics.GoroutineWrapperFunc(log, logger.BackendLog)
 )

apiserver/logger/logger.go

@@ -3,11 +3,13 @@ package logger
 import (
 	"fmt"
 	"github.com/daglabs/btcd/logs"
+	"github.com/pkg/errors"
 	"os"
 )
 
 // BackendLog is the logging backend used to create all subsystem loggers.
 var BackendLog = logs.NewBackend()
+var loggers []logs.Logger
 
 // InitLog attaches log file and error log file to the backend log.
 func InitLog(logFile, errLogFile string) {
@@ -22,3 +24,24 @@ func InitLog(logFile, errLogFile string) {
 		os.Exit(1)
 	}
 }
+
+// Logger returns a new logger for a particular subsystem that writes to
+// BackendLog, and add it to a slice so it will be possible to access it
+// later and change its log level
+func Logger(subsystemTag string) logs.Logger {
+	logger := BackendLog.Logger(subsystemTag)
+	loggers = append(loggers, logger)
+	return logger
+}
+
+// SetLogLevels sets the logging level for all of the subsystems in the API server.
+func SetLogLevels(level string) error {
+	lvl, ok := logs.LevelFromString(level)
+	if !ok {
+		return errors.Errorf("Invalid log level %s", level)
+	}
+	for _, logger := range loggers {
+		logger.SetLevel(lvl)
+	}
+	return nil
+}

apiserver/main.go

@@ -21,7 +21,7 @@ import (
 func main() {
 	defer panics.HandlePanic(log, logger.BackendLog, nil)
 
-	cfg, err := config.Parse()
+	err := config.Parse()
 	if err != nil {
 		errString := fmt.Sprintf("Error parsing command-line arguments: %s", err)
 		_, fErr := fmt.Fprintf(os.Stderr, errString)
@@ -31,7 +31,7 @@ func main() {
 		return
 	}
 
-	if cfg.Migrate {
+	if config.ActiveConfig().Migrate {
 		err := database.Migrate()
 		if err != nil {
 			panic(errors.Errorf("Error migrating database: %s", err))

apiserver/mqtt/log.go

@@ -4,6 +4,6 @@ import "github.com/daglabs/btcd/util/panics"
 import "github.com/daglabs/btcd/apiserver/logger"
 
 var (
-	log   = logger.BackendLog.Logger("MQTT")
+	log   = logger.Logger("MQTT")
 	spawn = panics.GoroutineWrapperFunc(log, logger.BackendLog)
 )

apiserver/server/log.go

@@ -4,6 +4,6 @@ import "github.com/daglabs/btcd/util/panics"
 import "github.com/daglabs/btcd/apiserver/logger"
 
 var (
-	log   = logger.BackendLog.Logger("REST")
+	log   = logger.Logger("REST")
 	spawn = panics.GoroutineWrapperFunc(log, logger.BackendLog)
 )