From 757cf83b7eac648f964cf02b1eca12a70f4088c0 Mon Sep 17 00:00:00 2001
From: Etienne Perot <eperot@google.com>
Date: Tue, 2 Jan 2024 18:39:36 -0800
Subject: [PATCH] Add call site information to JSON-formatted logs.

PiperOrigin-RevId: 595258070
---
 pkg/log/json.go     | 13 +++++++++++--
 pkg/log/json_k8s.go | 13 +++++++++++--
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/pkg/log/json.go b/pkg/log/json.go
index a7f55a9f9..a57bc101f 100644
--- a/pkg/log/json.go
+++ b/pkg/log/json.go
@@ -17,6 +17,8 @@ package log
 import (
 	"encoding/json"
 	"fmt"
+	"runtime"
+	"strings"
 	"time"
 )
 
@@ -62,9 +64,16 @@ type JSONEmitter struct {
 }
 
 // Emit implements Emitter.Emit.
-func (e JSONEmitter) Emit(_ int, level Level, timestamp time.Time, format string, v ...any) {
+func (e JSONEmitter) Emit(depth int, level Level, timestamp time.Time, format string, v ...any) {
+	logLine := fmt.Sprintf(format, v...)
+	if _, file, line, ok := runtime.Caller(depth + 1); ok {
+		if slash := strings.LastIndexByte(file, byte('/')); slash >= 0 {
+			file = file[slash+1:] // Trim any directory path from the file.
+		}
+		logLine = fmt.Sprintf("%s:%d] %s", file, line, logLine)
+	}
 	j := jsonLog{
-		Msg:   fmt.Sprintf(format, v...),
+		Msg:   logLine,
 		Level: level,
 		Time:  timestamp,
 	}
diff --git a/pkg/log/json_k8s.go b/pkg/log/json_k8s.go
index 0105c0682..8f5aab5a9 100644
--- a/pkg/log/json_k8s.go
+++ b/pkg/log/json_k8s.go
@@ -17,6 +17,8 @@ package log
 import (
 	"encoding/json"
 	"fmt"
+	"runtime"
+	"strings"
 	"time"
 )
 
@@ -33,9 +35,16 @@ type K8sJSONEmitter struct {
 }
 
 // Emit implements Emitter.Emit.
-func (e K8sJSONEmitter) Emit(_ int, level Level, timestamp time.Time, format string, v ...any) {
+func (e K8sJSONEmitter) Emit(depth int, level Level, timestamp time.Time, format string, v ...any) {
+	logLine := fmt.Sprintf(format, v...)
+	if _, file, line, ok := runtime.Caller(depth + 1); ok {
+		if slash := strings.LastIndexByte(file, byte('/')); slash >= 0 {
+			file = file[slash+1:] // Trim any directory path from the file.
+		}
+		logLine = fmt.Sprintf("%s:%d] %s", file, line, logLine)
+	}
 	j := k8sJSONLog{
-		Log:   fmt.Sprintf(format, v...),
+		Log:   logLine,
 		Level: level,
 		Time:  timestamp,
 	}