fix: RabbitMQ 상태 모니터링 및 백그라운드 재시도 추가 (#124)

- RabbitMQInitializer를 BackgroundService로 변경 (30초 간격 재시도)
- RabbitMQConnection에 IsConnected 속성 추가
- Health check에 RabbitMQ 연결/초기화 상태 반영
- DI 등록 변경 (Singleton + HostedService 패턴)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

SPMS.API/Controllers/PublicController.cs

@@ -4,6 +4,7 @@ using Microsoft.EntityFrameworkCore;
 using Swashbuckle.AspNetCore.Annotations;
 using SPMS.Domain.Common;
 using SPMS.Infrastructure;
+using SPMS.Infrastructure.Messaging;
 
 namespace SPMS.API.Controllers;
 
@@ -14,10 +15,17 @@ namespace SPMS.API.Controllers;
 public class PublicController : ControllerBase
 {
     private readonly AppDbContext _dbContext;
+    private readonly RabbitMQConnection _rabbitConnection;
+    private readonly RabbitMQInitializer _rabbitInitializer;
 
-    public PublicController(AppDbContext dbContext)
+    public PublicController(
+        AppDbContext dbContext,
+        RabbitMQConnection rabbitConnection,
+        RabbitMQInitializer rabbitInitializer)
     {
         _dbContext = dbContext;
+        _rabbitConnection = rabbitConnection;
+        _rabbitInitializer = rabbitInitializer;
     }
 
     [HttpPost("health")]
@@ -39,11 +47,26 @@ public class PublicController : ControllerBase
             allHealthy = false;
         }
 
-        // 2. Redis 연결 확인 (Phase 2에서 구현 예정)
+        // 2. Redis 연결 확인 (Phase 3-2에서 구현 예정)
         checks["redis"] = new { status = "not_configured" };
 
-        // 3. RabbitMQ 연결 확인 (Phase 2에서 구현 예정)
-        checks["rabbitmq"] = new { status = "not_configured" };
+        // 3. RabbitMQ 연결 확인
+        var rabbitConnected = _rabbitConnection.IsConnected;
+        var rabbitInitialized = _rabbitInitializer.IsInitialized;
+        if (rabbitConnected && rabbitInitialized)
+        {
+            checks["rabbitmq"] = new { status = "healthy" };
+        }
+        else
+        {
+            checks["rabbitmq"] = new
+            {
+                status = "unhealthy",
+                connected = rabbitConnected,
+                initialized = rabbitInitialized
+            };
+            allHealthy = false;
+        }
 
         if (allHealthy)
         {

SPMS.Infrastructure/DependencyInjection.cs

@@ -58,7 +58,8 @@ public static class DependencyInjection
         // RabbitMQ
         services.Configure<RabbitMQSettings>(configuration.GetSection(RabbitMQSettings.SectionName));
         services.AddSingleton<RabbitMQConnection>();
-        services.AddHostedService<RabbitMQInitializer>();
+        services.AddSingleton<RabbitMQInitializer>();
+        services.AddHostedService(sp => sp.GetRequiredService<RabbitMQInitializer>());
         services.AddScoped<IPushQueueService, PushQueueService>();
 
         // Push Senders

SPMS.Infrastructure/Messaging/RabbitMQConnection.cs

@@ -12,6 +12,8 @@ public class RabbitMQConnection : IAsyncDisposable
     private readonly SemaphoreSlim _semaphore = new(1, 1);
     private IConnection? _connection;
 
+    public bool IsConnected => _connection is { IsOpen: true };
+
     public RabbitMQConnection(
         IOptions<RabbitMQSettings> settings,
         ILogger<RabbitMQConnection> logger)

SPMS.Infrastructure/Messaging/RabbitMQInitializer.cs

@@ -6,11 +6,14 @@ using SPMS.Application.Settings;
 
 namespace SPMS.Infrastructure.Messaging;
 
-public class RabbitMQInitializer : IHostedService
+public class RabbitMQInitializer : BackgroundService
 {
     private readonly RabbitMQConnection _connection;
     private readonly RabbitMQSettings _settings;
     private readonly ILogger<RabbitMQInitializer> _logger;
+    private static readonly TimeSpan RetryInterval = TimeSpan.FromSeconds(30);
+
+    public bool IsInitialized { get; private set; }
 
     public RabbitMQInitializer(
         RabbitMQConnection connection,
@@ -22,19 +25,26 @@ public class RabbitMQInitializer : IHostedService
         _logger = logger;
     }
 
-    public async Task StartAsync(CancellationToken cancellationToken)
+    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
     {
-        try
+        while (!stoppingToken.IsCancellationRequested)
         {
-            await InitializeAsync(cancellationToken);
-        }
-        catch (Exception ex)
-        {
-            _logger.LogWarning(ex, "RabbitMQ 초기화 실패 — 서버는 계속 실행됩니다. 메시지 발송 시 재연결을 시도합니다.");
+            try
+            {
+                await InitializeAsync(stoppingToken);
+                IsInitialized = true;
+                _logger.LogInformation("RabbitMQ 초기화 완료");
+                return;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "RabbitMQ 초기화 실패 — {RetrySeconds}초 후 재시도합니다.", RetryInterval.TotalSeconds);
+                await Task.Delay(RetryInterval, stoppingToken);
+            }
         }
     }
 
-    public async Task InitializeAsync(CancellationToken cancellationToken)
+    private async Task InitializeAsync(CancellationToken cancellationToken)
     {
         await using var channel = await _connection.CreateChannelAsync(cancellationToken);
 
@@ -87,6 +97,4 @@ public class RabbitMQInitializer : IHostedService
         _logger.LogInformation("Queue 선언 및 바인딩 완료: {Queue} → {Exchange} (routing_key: schedule)",
             _settings.ScheduleQueue, _settings.Exchange);
     }
-
-    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
 }