Tenant header added (#194)

Added tenant headed to handle multi-tenancy setup - https://grafana.com/docs/loki/latest/operations/multi-tenancy/

Author: mgalczynski

src/Serilog.Sinks.Grafana.Loki/HttpClients/BaseLokiHttpClient.cs

@@ -10,6 +10,7 @@
 
 using System.Net.Http.Headers;
 using System.Text;
+using System.Text.RegularExpressions;
 
 namespace Serilog.Sinks.Grafana.Loki.HttpClients;
 
@@ -24,6 +25,16 @@ public abstract class BaseLokiHttpClient : ILokiHttpClient
     /// </summary>
     protected readonly HttpClient HttpClient;
 
+    /// <summary>
+    /// Header used for passing tenant ID. See <a href="https://grafana.com/docs/loki/latest/operations/multi-tenancy/">docs</a>.
+    /// </summary>
+    private const string TenantHeader = "X-Scope-OrgID";
+
+    /// <summary>
+    /// Regex for Tenant ID validation.
+    /// </summary>
+    private static readonly Regex TenantIdValueRegex = new Regex(@"^[a-zA-Z0-9]*$");
+
     /// <summary>
     /// Initializes a new instance of the <see cref="BaseLokiHttpClient"/> class.
     /// </summary>
@@ -57,6 +68,29 @@ public virtual void SetCredentials(LokiCredentials? credentials)
         headers.Authorization = new AuthenticationHeaderValue("Basic", token);
     }
 
+    /// <inheritdoc/>
+    public virtual void SetTenant(string? tenant)
+    {
+        if (string.IsNullOrEmpty(tenant))
+        {
+            return;
+        }
+
+        if (!TenantIdValueRegex.IsMatch(tenant))
+        {
+            throw new ArgumentException($"{tenant} argument does not follow rule for Tenant ID", nameof(tenant));
+        }
+
+        var headers = HttpClient.DefaultRequestHeaders;
+
+        if (headers.Any(h => h.Key == TenantHeader))
+        {
+            return;
+        }
+
+        headers.Add(TenantHeader, tenant);
+    }
+
     /// <inheritdoc/>
     public virtual void Dispose() => HttpClient.Dispose();
 

src/Serilog.Sinks.Grafana.Loki/ILokiHttpClient.cs

@@ -34,4 +34,12 @@ public interface ILokiHttpClient : IDisposable
     ///     <see cref="LokiCredentials"/> used for authorization.
     /// </param>
     void SetCredentials(LokiCredentials? credentials);
+
+    /// <summary>
+    /// Adds tenant header to all requests. See <a href="https://grafana.com/docs/loki/latest/operations/multi-tenancy/">docs</a>.
+    /// </summary>
+    /// <param name="tenant">
+    ///     Tenant ID
+    /// </param>
+    void SetTenant(string? tenant);
 }

src/Serilog.Sinks.Grafana.Loki/LoggerConfigurationLokiExtensions.cs

@@ -45,6 +45,9 @@ public static class LoggerConfigurationLokiExtensions
     /// <param name="credentials">
     /// Auth <see cref="LokiCredentials"/>.
     /// </param>
+    /// <param name="tenant">
+    /// Tenant ID See <a href="https://grafana.com/docs/loki/latest/operations/multi-tenancy/">docs</a>.
+    /// </param>
     /// <param name="restrictedToMinimumLevel">
     /// The minimum level for events passed through the sink.
     /// Default value is <see cref="LevelAlias.Minimum"/>.
@@ -83,6 +86,7 @@ public static LoggerConfiguration GrafanaLoki(
         IEnumerable<LokiLabel>? labels = null,
         IEnumerable<string>? propertiesAsLabels = null,
         LokiCredentials? credentials = null,
+        string? tenant = null,
         LogEventLevel restrictedToMinimumLevel = LevelAlias.Minimum,
         int batchPostingLimit = 1000,
         int? queueLimit = null,
@@ -104,6 +108,7 @@ public static LoggerConfiguration GrafanaLoki(
         httpClient ??= new LokiHttpClient();
 
         httpClient.SetCredentials(credentials);
+        httpClient.SetTenant(tenant);
 
         var batchFormatter = new LokiBatchFormatter(
             reservedPropertyRenamingStrategy,

test/Serilog.Sinks.Grafana.Loki.Tests/HttpClientsTests/BaseLokiHttpClientTests.cs

@@ -47,4 +47,35 @@ public void AuthorizationHeaderShouldNotBeSetWithoutCredentials()
 
         client.Client.DefaultRequestHeaders.Authorization.ShouldBeNull();
     }
+
+    [Fact]
+    public void TenantHeaderShouldBeCorrect()
+    {
+        var tenantId = "lokitenant";
+        using var client = new TestLokiHttpClient();
+
+        client.SetTenant(tenantId);
+
+        var tenantHeaders = client.Client.DefaultRequestHeaders.GetValues("X-Scope-OrgID").ToList();
+        tenantHeaders.ShouldBeEquivalentTo(new List<string> {"lokitenant"});
+    }
+
+    [Fact]
+    public void TenantHeaderShouldNotBeSetWithoutTenantId()
+    {
+        using var client = new TestLokiHttpClient();
+
+        client.SetTenant(null);
+
+        client.Client.DefaultRequestHeaders.Contains("X-Scope-OrgID").ShouldBeFalse();
+    }
+
+    [Fact]
+    public void TenantHeaderShouldThrowAnExceptionOnTenantIdAgainstRule()
+    {
+        var tenantId = "non-alphanumerical tenant";
+        using var client = new TestLokiHttpClient();
+
+        Should.Throw<ArgumentException>(() => client.SetTenant(tenantId));
+    }
 }