bin/crowdsec: avoid writing errors twice when log_media=stdout (#2729)

* bin/crowdsec: avoid writing errors twice when log_media=stdout
* lint

cmd/crowdsec/hook.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"io"
+	"os"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type ConditionalHook struct {
+	Writer    io.Writer
+	LogLevels []log.Level
+	Enabled   bool
+}
+
+func (hook *ConditionalHook) Fire(entry *log.Entry) error {
+	if hook.Enabled {
+		line, err := entry.String()
+		if err != nil {
+			return err
+		}
+
+		_, err = hook.Writer.Write([]byte(line))
+
+		return err
+	}
+
+	return nil
+}
+
+func (hook *ConditionalHook) Levels() []log.Level {
+	return hook.LogLevels
+}
+
+// The primal logging hook is set up before parsing config.yaml.
+// Once config.yaml is parsed, the primal hook is disabled if the
+// configured logger is writing to stderr. Otherwise it's used to
+// report fatal errors and panics to stderr in addition to the log file.
+var primalHook = &ConditionalHook{
+	Writer:    os.Stderr,
+	LogLevels: []log.Level{log.FatalLevel, log.PanicLevel},
+	Enabled:   true,
+}

cmd/crowdsec/main.go

@@ -80,11 +80,13 @@ func LoadBuckets(cConfig *csconfig.Config, hub *cwhub.Hub) error {
 		err   error
 		files []string
 	)
+
 	for _, hubScenarioItem := range hub.GetItemMap(cwhub.SCENARIOS) {
 		if hubScenarioItem.State.Installed {
 			files = append(files, hubScenarioItem.State.LocalPath)
 		}
 	}
+
 	buckets = leakybucket.NewBuckets()
 
 	log.Infof("Loading %d scenario files", len(files))
@@ -99,6 +101,7 @@ func LoadBuckets(cConfig *csconfig.Config, hub *cwhub.Hub) error {
 			holders[holderIndex].Profiling = true
 		}
 	}
+
 	return nil
 }
 
@@ -143,8 +146,10 @@ func (l labelsMap) Set(label string) error {
 		if len(split) != 2 {
 			return fmt.Errorf("invalid format for label '%s', must be key:value", pair)
 		}
+
 		l[split[0]] = split[1]
 	}
+
 	return nil
 }
 
@@ -168,9 +173,11 @@ func (f *Flags) Parse() {
 	flag.BoolVar(&f.DisableAPI, "no-api", false, "disable local API")
 	flag.BoolVar(&f.DisableCAPI, "no-capi", false, "disable communication with Central API")
 	flag.BoolVar(&f.OrderEvent, "order-event", false, "enforce event ordering with significant performance cost")
+
 	if runtime.GOOS == "windows" {
 		flag.StringVar(&f.WinSvc, "winsvc", "", "Windows service Action: Install, Remove etc..")
 	}
+
 	flag.StringVar(&dumpFolder, "dump-data", "", "dump parsers/buckets raw outputs")
 	flag.Parse()
 }
@@ -205,6 +212,7 @@ func newLogLevel(curLevelPtr *log.Level, f *Flags) *log.Level {
 		// avoid returning a new ptr to the same value
 		return curLevelPtr
 	}
+
 	return &ret
 }
 
@@ -238,6 +246,8 @@ func LoadConfig(configFile string, disableAgent bool, disableAPI bool, quiet boo
 		return nil, err
 	}
 
+	primalHook.Enabled = (cConfig.Common.LogMedia != "stdout")
+
 	if err := csconfig.LoadFeatureFlagsFile(configFile, log.StandardLogger()); err != nil {
 		return nil, err
 	}
@@ -282,6 +292,7 @@ func LoadConfig(configFile string, disableAgent bool, disableAPI bool, quiet boo
 		if cConfig.DisableAPI {
 			cConfig.Common.Daemonize = false
 		}
+
 		log.Infof("single file mode : log_media=%s daemonize=%t", cConfig.Common.LogMedia, cConfig.Common.Daemonize)
 	}
 
@@ -291,6 +302,7 @@ func LoadConfig(configFile string, disableAgent bool, disableAPI bool, quiet boo
 
 	if cConfig.Common.Daemonize && runtime.GOOS == "windows" {
 		log.Debug("Daemonization is not supported on Windows, disabling")
+
 		cConfig.Common.Daemonize = false
 	}
 
@@ -308,6 +320,8 @@ func LoadConfig(configFile string, disableAgent bool, disableAPI bool, quiet boo
 var crowdsecT0 time.Time
 
 func main() {
+	log.AddHook(primalHook)
+
 	if err := fflag.RegisterAllFeatures(); err != nil {
 		log.Fatalf("failed to register features: %s", err)
 	}
@@ -342,5 +356,6 @@ func main() {
 	if err != nil {
 		log.Fatal(err)
 	}
+
 	os.Exit(0)
 }

cmd/crowdsec/run_in_svc.go

@@ -4,10 +4,8 @@ package main
 
 import (
 	"fmt"
-	"os"
 
 	log "github.com/sirupsen/logrus"
-	"github.com/sirupsen/logrus/hooks/writer"
 
 	"github.com/crowdsecurity/go-cs-lib/trace"
 	"github.com/crowdsecurity/go-cs-lib/version"
@@ -24,16 +22,6 @@ func StartRunSvc() error {
 
 	defer trace.CatchPanic("crowdsec/StartRunSvc")
 
-	// Set a default logger with level=fatal on stderr,
-	// in addition to the one we configure afterwards
-	log.AddHook(&writer.Hook{
-		Writer: os.Stderr,
-		LogLevels: []log.Level{
-			log.PanicLevel,
-			log.FatalLevel,
-		},
-	})
-
 	if cConfig, err = LoadConfig(flags.ConfigFile, flags.DisableAgent, flags.DisableAPI, false); err != nil {
 		return err
 	}
@@ -46,6 +34,7 @@ func StartRunSvc() error {
 	// Enable profiling early
 	if cConfig.Prometheus != nil {
 		var dbClient *database.Client
+
 		var err error
 
 		if cConfig.DbConfig != nil {
@@ -55,8 +44,11 @@ func StartRunSvc() error {
 				return fmt.Errorf("unable to create database client: %s", err)
 			}
 		}
+
 		registerPrometheus(cConfig.Prometheus)
+
 		go servePrometheus(cConfig.Prometheus, dbClient, apiReady, agentReady)
 	}
+
 	return Serve(cConfig, apiReady, agentReady)
 }