Send Slack webhook when a user registers

Author: Daniel Medin

BitStoreWeb/BitStoreWeb.Net9/Controllers/AccountController.cs

@@ -16,11 +16,16 @@ public class AccountController : Controller
     private const string RegisterMode = "register";
 
     private readonly IUserAuthService _userAuthService;
+    private readonly IUserRegistrationNotifier _userRegistrationNotifier;
     private readonly AppDbContext _db;
 
-    public AccountController(IUserAuthService userAuthService, AppDbContext db)
+    public AccountController(
+        IUserAuthService userAuthService,
+        IUserRegistrationNotifier userRegistrationNotifier,
+        AppDbContext db)
     {
         _userAuthService = userAuthService;
+        _userRegistrationNotifier = userRegistrationNotifier;
         _db = db;
     }
 
@@ -88,6 +93,11 @@ await HttpContext.SignInAsync(
             new ClaimsPrincipal(claimsIdentity),
             authProperties);
 
+        if (authMode == RegisterMode)
+        {
+            await _userRegistrationNotifier.NotifyUserRegisteredAsync(user);
+        }
+
         return RedirectToLocal(returnUrl);
     }
 

BitStoreWeb/BitStoreWeb.Net9/Program.cs

@@ -43,6 +43,7 @@
 });
 builder.Services.AddScoped<IPasswordHasher<BitStoreWeb.Net9.Models.AppUser>, PasswordHasher<BitStoreWeb.Net9.Models.AppUser>>();
 builder.Services.AddScoped<IUserAuthService, UserAuthService>();
+builder.Services.AddHttpClient<IUserRegistrationNotifier, SlackUserRegistrationNotifier>();
 builder.Services.AddEndpointsApiExplorer();
 builder.Services.AddSwaggerGen(options =>
 {

BitStoreWeb/BitStoreWeb.Net9/Services/IUserRegistrationNotifier.cs

@@ -0,0 +1,8 @@
+using BitStoreWeb.Net9.Models;
+
+namespace BitStoreWeb.Net9.Services;
+
+public interface IUserRegistrationNotifier
+{
+    Task NotifyUserRegisteredAsync(AppUser user);
+}

BitStoreWeb/BitStoreWeb.Net9/Services/SlackUserRegistrationNotifier.cs

@@ -0,0 +1,52 @@
+using System.Net.Http.Json;
+using BitStoreWeb.Net9.Models;
+
+namespace BitStoreWeb.Net9.Services;
+
+public class SlackUserRegistrationNotifier : IUserRegistrationNotifier
+{
+    private const string WebhookConfigKey = "Slack:RegistrationWebhookUrl";
+
+    private readonly HttpClient _httpClient;
+    private readonly IConfiguration _configuration;
+    private readonly ILogger<SlackUserRegistrationNotifier> _logger;
+
+    public SlackUserRegistrationNotifier(
+        HttpClient httpClient,
+        IConfiguration configuration,
+        ILogger<SlackUserRegistrationNotifier> logger)
+    {
+        _httpClient = httpClient;
+        _configuration = configuration;
+        _logger = logger;
+    }
+
+    public async Task NotifyUserRegisteredAsync(AppUser user)
+    {
+        var webhookUrl = _configuration[WebhookConfigKey];
+        if (string.IsNullOrWhiteSpace(webhookUrl))
+        {
+            return;
+        }
+
+        var payload = new
+        {
+            text = $"New BitStore account registered: {user.UserName} (role: {user.Role}) at {DateTime.UtcNow:yyyy-MM-dd HH:mm:ss} UTC."
+        };
+
+        try
+        {
+            using var response = await _httpClient.PostAsJsonAsync(webhookUrl, payload);
+            if (!response.IsSuccessStatusCode)
+            {
+                _logger.LogWarning(
+                    "Slack registration webhook failed with status {StatusCode}.",
+                    (int)response.StatusCode);
+            }
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Slack registration webhook call failed.");
+        }
+    }
+}

BitStoreWeb/BitStoreWeb.Net9/appsettings.Development.json

@@ -3,6 +3,9 @@
     "DefaultConnection": "Data Source=bitstore.db"
   },
   "DatabaseProvider": "Sqlite",
+  "Slack": {
+    "RegistrationWebhookUrl": ""
+  },
   "Logging": {
     "LogLevel": {
       "Default": "Information",

BitStoreWeb/BitStoreWeb.Net9/appsettings.Production.json

@@ -1,5 +1,8 @@
 {
   "DatabaseProvider": "SqlServer",
+  "Slack": {
+    "RegistrationWebhookUrl": ""
+  },
   "Logging": {
     "LogLevel": {
       "Default": "Information",

BitStoreWeb/BitStoreWeb.Net9/appsettings.json

@@ -3,6 +3,9 @@
     "DefaultConnection": "Data Source=bitstore.db"
   },
   "DatabaseProvider": "Sqlite",
+  "Slack": {
+    "RegistrationWebhookUrl": ""
+  },
   "Logging": {
     "LogLevel": {
       "Default": "Information",

BitStoreWeb/docs/DEPLOY_AZURE.md

@@ -46,6 +46,7 @@ In App Service -> **Environment variables**, add:
 
 - `DatabaseProvider` = `SqlServer`
 - `ConnectionStrings__DefaultConnection` = your Azure SQL connection string
+- `Slack__RegistrationWebhookUrl` = your Slack Incoming Webhook URL (optional, for new-user alerts)
 
 Example connection string: