From f569211967dee28be922c4af34c5161fdd3c2385 Mon Sep 17 00:00:00 2001
From: kjh2064 <kjh2064@gmail.com>
Date: Mon, 29 Jun 2026 11:35:27 +0900
Subject: [PATCH] =?UTF-8?q?feat:=20Serilog=20=EA=B8=B0=EB=B0=98=20?=
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 =?UTF-8?q?=EB=8F=99?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 TaxBaik.Web/Logging/TelegramSink.cs | 85 +++++++++++++++++++++++++++++
 TaxBaik.Web/Program.cs              |  7 +++
 2 files changed, 92 insertions(+)
 create mode 100644 TaxBaik.Web/Logging/TelegramSink.cs

diff --git a/TaxBaik.Web/Logging/TelegramSink.cs b/TaxBaik.Web/Logging/TelegramSink.cs
new file mode 100644
index 0000000..10f5318
--- /dev/null
+++ b/TaxBaik.Web/Logging/TelegramSink.cs
@@ -0,0 +1,85 @@
+using System;
+using System.Net.Http;
+using System.Net.Http.Json;
+using System.Text;
+using System.Threading.Tasks;
+using Serilog.Core;
+using Serilog.Events;
+
+namespace TaxBaik.Web.Logging;
+
+public class TelegramSink : ILogEventSink
+{
+    private readonly string _botToken;
+    private readonly string _chatId;
+    private readonly HttpClient _httpClient;
+
+    public TelegramSink(string botToken, string chatId)
+    {
+        _botToken = botToken;
+        _chatId = chatId;
+        _httpClient = new HttpClient();
+    }
+
+    public void Emit(LogEvent logEvent)
+    {
+        if (logEvent.Level < LogEventLevel.Error)
+        {
+            return;
+        }
+
+        // Emit is a synchronous method, so we dispatch the network call asynchronously
+        Task.Run(async () =>
+        {
+            try
+            {
+                var timestamp = logEvent.Timestamp.ToString("yyyy-MM-dd HH:mm:ss.fff zzz");
+                var level = logEvent.Level.ToString().ToUpper();
+                var message = logEvent.RenderMessage();
+                var exceptionDetails = logEvent.Exception?.ToString();
+
+                var sb = new StringBuilder();
+                sb.AppendLine($"<b>🚨 [{level}] 에러 발생</b>");
+                sb.AppendLine($"<b>시간:</b> {timestamp}");
+                sb.AppendLine($"<b>메시지:</b> {EscapeHtml(message)}");
+
+                if (!string.IsNullOrEmpty(exceptionDetails))
+                {
+                    var escapedException = EscapeHtml(exceptionDetails);
+                    if (escapedException.Length > 3000)
+                    {
+                        escapedException = escapedException.Substring(0, 3000) + "\n[이하 생략]";
+                    }
+                    sb.AppendLine($"<b>Exception 상세:</b>\n<pre>{escapedException}</pre>");
+                }
+
+                var url = $"https://api.telegram.org/bot{_botToken}/sendMessage";
+                var payload = new
+                {
+                    chat_id = _chatId,
+                    text = sb.ToString(),
+                    parse_mode = "HTML"
+                };
+
+                var response = await _httpClient.PostAsJsonAsync(url, payload);
+                if (!response.IsSuccessStatusCode)
+                {
+                    var errorResponse = await response.Content.ReadAsStringAsync();
+                    Console.WriteLine($"[TelegramSink] Failed to send log to Telegram: {response.StatusCode} - {errorResponse}");
+                }
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"[TelegramSink] Error in TelegramSink: {ex.Message}");
+            }
+        });
+    }
+
+    private static string EscapeHtml(string text)
+    {
+        if (string.IsNullOrEmpty(text)) return text;
+        return text.Replace("&", "&amp;")
+                   .Replace("<", "&lt;")
+                   .Replace(">", "&gt;");
+    }
+}
diff --git a/TaxBaik.Web/Program.cs b/TaxBaik.Web/Program.cs
index 0cc60fb..64c20cc 100644
--- a/TaxBaik.Web/Program.cs
+++ b/TaxBaik.Web/Program.cs
@@ -38,6 +38,13 @@ builder.Host.UseSerilog((context, config) =>
             outputTemplate: "[{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz}] [{Level:u3}] {Message:lj}{NewLine}{Exception}")
         .Enrich.FromLogContext()
         .Enrich.WithProperty("Environment", context.HostingEnvironment.EnvironmentName);
+
+    var botToken = context.Configuration["Telegram:BotToken"];
+    var systemChatId = context.Configuration["Telegram:SystemChatId"] ?? context.Configuration["Telegram:ChatId"];
+    if (!string.IsNullOrEmpty(botToken) && !string.IsNullOrEmpty(systemChatId))
+    {
+        config.WriteTo.Sink(new TaxBaik.Web.Logging.TelegramSink(botToken, systemChatId), Serilog.Events.LogEventLevel.Error);
+    }
 });
 
 // Controllers (API)
-- 
2.52.0