[PM-29460] feat: Authenticate PricingClient to the pricing service

src/Core/Billing/Pricing/ServiceCollectionExtensions.cs

@@ -21,6 +21,10 @@ public static void AddPricingClient(this IServiceCollection services)
                 "Bitwarden-Region",
                 globalSettings.BaseServiceUri.CloudRegion?.ToLower(CultureInfo.InvariantCulture) ?? "us"
             );
+            if (!string.IsNullOrEmpty(globalSettings.PricingApiKey))
+            {
+                httpClient.DefaultRequestHeaders.Add("X-Pricing-Api-Key", globalSettings.PricingApiKey);
+            }
         });
     }
 }

src/Core/Settings/GlobalSettings.cs

@@ -101,6 +101,7 @@ public virtual string MailTemplateDirectory
     /// </summary>
     public virtual string SendDefaultHashKey { get; set; }
     public virtual string PricingUri { get; set; }
+    public virtual string PricingApiKey { get; set; }
     public virtual Fido2Settings Fido2 { get; set; } = new Fido2Settings();
     public virtual ICommunicationSettings Communication { get; set; } = new CommunicationSettings();
 

test/Core.Test/Billing/Pricing/ServiceCollectionExtensionsTests.cs

@@ -0,0 +1,60 @@
+using Bit.Core.Billing.Pricing;
+using Bit.Core.Settings;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit;
+
+namespace Bit.Core.Test.Billing.Pricing;
+
+public class ServiceCollectionExtensionsTests
+{
+    private const string PricingApiKeyHeader = "X-Pricing-Api-Key";
+
+    // Obviously-synthetic test value; the server does not enforce the pricing
+    // service's >=32 character rule, so any non-empty value exercises the guard.
+    private const string ApiKey = "test-pricing-api-key-0123456789abcdef";
+
+    [Fact]
+    public void AddPricingClient_WhenApiKeyConfigured_SendsApiKeyHeader()
+    {
+        // Arrange
+        var services = new ServiceCollection();
+        services.AddSingleton(new GlobalSettings
+        {
+            PricingUri = "https://test.com/",
+            PricingApiKey = ApiKey
+        });
+        services.AddLogging();
+        services.AddPricingClient();
+
+        using var provider = services.BuildServiceProvider();
+
+        // Act
+        var httpClient = provider
+            .GetRequiredService<IHttpClientFactory>()
+            .CreateClient(nameof(IPricingClient));
+
+        // Assert
+        Assert.True(httpClient.DefaultRequestHeaders.Contains(PricingApiKeyHeader));
+        Assert.Equal(ApiKey, httpClient.DefaultRequestHeaders.GetValues(PricingApiKeyHeader).Single());
+    }
+
+    [Fact]
+    public void AddPricingClient_WhenApiKeyNotConfigured_DoesNotSendApiKeyHeader()
+    {
+        // Arrange
+        var services = new ServiceCollection();
+        services.AddSingleton(new GlobalSettings { PricingUri = "https://test.com/" });
+        services.AddLogging();
+        services.AddPricingClient();
+
+        using var provider = services.BuildServiceProvider();
+
+        // Act
+        var httpClient = provider
+            .GetRequiredService<IHttpClientFactory>()
+            .CreateClient(nameof(IPricingClient));
+
+        // Assert
+        Assert.False(httpClient.DefaultRequestHeaders.Contains(PricingApiKeyHeader));
+    }
+}