From 4af6ca9e3b83ef0058921a7431cebc2a55bcab9f Mon Sep 17 00:00:00 2001
From: Sven Walter <s.walter@rebuy.com>
Date: Fri, 3 May 2024 17:58:50 +0200
Subject: [PATCH] add function to extract subsystem from context

---
 pkg/logutil/context.go | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/pkg/logutil/context.go b/pkg/logutil/context.go
index 3d0c74f..dbd1524 100644
--- a/pkg/logutil/context.go
+++ b/pkg/logutil/context.go
@@ -25,6 +25,16 @@ type meta struct {
 	log  logrus.FieldLogger
 }
 
+func (m meta) subsystem() string {
+	subsystems := []string{"/"}
+
+	for _, t := range m.path {
+		subsystems = append(subsystems, t.subsystem)
+	}
+
+	return path.Join(subsystems...)
+}
+
 type trace struct {
 	id        string
 	subsystem string
@@ -40,6 +50,15 @@ func Get(ctx context.Context) logrus.FieldLogger {
 	return m.log
 }
 
+// GetSubsystem extracts the name of the subsystem from the given context.
+func GetSubsystem(ctx context.Context) string {
+	m, ok := ctx.Value(contextKeyMeta).(meta)
+	if !ok {
+		return ""
+	}
+	return m.subsystem()
+}
+
 // Start creates a new logger and stores it in the returned context.
 // Additionally it creates a new trace ID and injects them into the new logger
 // together with previous trace IDs from the given context.
@@ -55,18 +74,15 @@ func Start(ctx context.Context, subsystem string, opts ...ContextOption) context
 		subsystem: subsystem,
 	})
 
-	subsystems := []string{"/"}
 	ids := []string{}
 
 	for _, t := range m.path {
 		name := fmt.Sprintf("trace-id-%s", t.subsystem)
 		m.log = m.log.WithField(name, t.id)
-
-		subsystems = append(subsystems, t.subsystem)
 		ids = append(ids, t.id)
 	}
 
-	m.log = m.log.WithField("subsystem", path.Join(subsystems...))
+	m.log = m.log.WithField("subsystem", m.subsystem())
 	m.log = m.log.WithField("trace-id", strings.Join(ids, "-"))
 
 	for _, opt := range opts {
@@ -126,10 +142,10 @@ func WithFields(ctx context.Context, fields logrus.Fields) context.Context {
 
 // FromStruct converts any struct into a valid logrus.Fields. It can be customized with the logfield annotation:
 //
-//     type Instance struct {
-//         InstanceID   string `logfield:"instance-id"`
-//         InstanceName string `logfield:"instance-name"`
-//     }
+//	type Instance struct {
+//	    InstanceID   string `logfield:"instance-id"`
+//	    InstanceName string `logfield:"instance-name"`
+//	}
 //
 // See mapstructure docs for more information:
 // https://pkg.go.dev/github.com/mitchellh/mapstructure?tab=doc