composer: add support for logrus syslog hook

Which will be used on crc in the log forwarding setup
NeededBy: COMPOSER-1285

cmd/osbuild-composer/config.go

@@ -14,6 +14,7 @@ type ComposerConfigFile struct {
 	Koji         KojiAPIConfig   `toml:"koji"`
 	Worker       WorkerAPIConfig `toml:"worker"`
 	WeldrAPI     WeldrAPIConfig  `toml:"weldr_api"`
+	SyslogServer string          `toml:"syslog_server" env:"SYSLOG_SERVER"`
 	LogLevel     string          `toml:"log_level"`
 	LogFormat    string          `toml:"log_format"`
 }

cmd/osbuild-composer/main.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/coreos/go-systemd/activation"
 	"github.com/sirupsen/logrus"
+	"github.com/sirupsen/logrus/hooks/syslog"
 )
 
 const (
@@ -69,6 +70,15 @@ func main() {
 		logrus.Fatal("CACHE_DIRECTORY is not set. Is the service file missing CacheDirectory=?")
 	}
 
+	if len(config.SyslogServer) > 0 {
+		hook, err := syslog.NewSyslogHook("tcp", config.SyslogServer, 0, "osbuild-composer")
+		if err != nil {
+			logrus.Fatal("Error connecting to syslog: " + err.Error())
+		}
+
+		logrus.AddHook(hook)
+	}
+
 	composer, err := NewComposer(config, stateDir, cacheDir)
 	if err != nil {
 		logrus.Fatalf("%v", err)

vendor/github.com/sirupsen/logrus/hooks/syslog/README.md

@@ -0,0 +1,39 @@
+# Syslog Hooks for Logrus <img src="http://i.imgur.com/hTeVwmJ.png" width="40" height="40" alt=":walrus:" class="emoji" title=":walrus:"/>
+
+## Usage
+
+```go
+import (
+  "log/syslog"
+  "github.com/sirupsen/logrus"
+  lSyslog "github.com/sirupsen/logrus/hooks/syslog"
+)
+
+func main() {
+  log       := logrus.New()
+  hook, err := lSyslog.NewSyslogHook("udp", "localhost:514", syslog.LOG_INFO, "")
+
+  if err == nil {
+    log.Hooks.Add(hook)
+  }
+}
+```
+
+If you want to connect to local syslog (Ex. "/dev/log" or "/var/run/syslog" or "/var/run/log"). Just assign empty string to the first two parameters of `NewSyslogHook`. It should look like the following.
+
+```go
+import (
+  "log/syslog"
+  "github.com/sirupsen/logrus"
+  lSyslog "github.com/sirupsen/logrus/hooks/syslog"
+)
+
+func main() {
+  log       := logrus.New()
+  hook, err := lSyslog.NewSyslogHook("", "", syslog.LOG_INFO, "")
+
+  if err == nil {
+    log.Hooks.Add(hook)
+  }
+}
+```

vendor/github.com/sirupsen/logrus/hooks/syslog/syslog.go

@@ -0,0 +1,55 @@
+// +build !windows,!nacl,!plan9
+
+package syslog
+
+import (
+	"fmt"
+	"log/syslog"
+	"os"
+
+	"github.com/sirupsen/logrus"
+)
+
+// SyslogHook to send logs via syslog.
+type SyslogHook struct {
+	Writer        *syslog.Writer
+	SyslogNetwork string
+	SyslogRaddr   string
+}
+
+// Creates a hook to be added to an instance of logger. This is called with
+// `hook, err := NewSyslogHook("udp", "localhost:514", syslog.LOG_DEBUG, "")`
+// `if err == nil { log.Hooks.Add(hook) }`
+func NewSyslogHook(network, raddr string, priority syslog.Priority, tag string) (*SyslogHook, error) {
+	w, err := syslog.Dial(network, raddr, priority, tag)
+	return &SyslogHook{w, network, raddr}, err
+}
+
+func (hook *SyslogHook) Fire(entry *logrus.Entry) error {
+	line, err := entry.String()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Unable to read entry, %v", err)
+		return err
+	}
+
+	switch entry.Level {
+	case logrus.PanicLevel:
+		return hook.Writer.Crit(line)
+	case logrus.FatalLevel:
+		return hook.Writer.Crit(line)
+	case logrus.ErrorLevel:
+		return hook.Writer.Err(line)
+	case logrus.WarnLevel:
+		return hook.Writer.Warning(line)
+	case logrus.InfoLevel:
+		return hook.Writer.Info(line)
+	case logrus.DebugLevel, logrus.TraceLevel:
+		return hook.Writer.Debug(line)
+	default:
+		return nil
+	}
+}
+
+func (hook *SyslogHook) Levels() []logrus.Level {
+	return logrus.AllLevels
+}

vendor/modules.txt

@@ -338,6 +338,7 @@ github.com/segmentio/ksuid
 # github.com/sirupsen/logrus v1.8.1
 ## explicit
 github.com/sirupsen/logrus
+github.com/sirupsen/logrus/hooks/syslog
 # github.com/sony/gobreaker v0.4.2-0.20210216022020-dd874f9dd33b
 github.com/sony/gobreaker
 # github.com/spf13/cobra v1.4.0