Merge branch 'dev'

samples/MvcCorrelationIdSample/Controllers/ValuesController.cs

@@ -32,7 +32,8 @@ public IEnumerable<string> Get()
                 $"DirectAccessor={correlation}",
                 $"Transient={_transient.GetCorrelationFromScoped}",
                 $"Scoped={_scoped.GetCorrelationFromScoped}",
-                $"Singleton={_singleton.GetCorrelationFromScoped}"
+                $"Singleton={_singleton.GetCorrelationFromScoped}",
+                $"TraceIdentifier={HttpContext.TraceIdentifier}"
             };
         }
     }

samples/MvcCorrelationIdSample/Properties/launchSettings.json

@@ -9,21 +9,21 @@
   },
   "profiles": {
     "IIS Express": {
-      "commandName": "IISExpress",
-      "launchBrowser": true,
-      "launchUrl": "api/values",
-      "environmentVariables": {
-        "ASPNETCORE_ENVIRONMENT": "Development"
-      }
+        "commandName": "IISExpress",
+        "launchBrowser": true,
+        "launchUrl": "http://localhost:59922/api/values",
+        "environmentVariables": {
+            "ASPNETCORE_ENVIRONMENT": "Development"
+        }
     },
     "MvcCorrelationIdSample": {
-      "commandName": "Project",
-      "launchBrowser": true,
-      "launchUrl": "api/values",
-      "environmentVariables": {
-        "ASPNETCORE_ENVIRONMENT": "Development"
-      },
-      "applicationUrl": "http://localhost:59923/"
+        "commandName": "Project",
+        "launchBrowser": true,
+        "launchUrl": "http://localhost:59923/api/values",
+        "environmentVariables": {
+            "ASPNETCORE_ENVIRONMENT": "Development"
+        },
+        "applicationUrl": "http://localhost:59923/"
     }
   }
 }

src/CorrelationId/CorrelationContext.cs

@@ -7,17 +7,26 @@ namespace CorrelationId
     /// </summary>
     public class CorrelationContext
     {
-        internal CorrelationContext(string correlationId)
+        internal CorrelationContext(string correlationId, string header)
         {
             if (string.IsNullOrEmpty(correlationId))
                 throw new ArgumentNullException(nameof(correlationId));
 
+            if (string.IsNullOrEmpty(header))
+                throw new ArgumentNullException(nameof(header));
+
             CorrelationId = correlationId;
+            Header = header;
         }
 
         /// <summary>
         /// The Correlation ID which is applicable to the current request.
         /// </summary>
         public string CorrelationId { get; }
+
+        /// <summary>
+        /// The name of the header from which the Correlation ID is read/written.
+        /// </summary>
+        public string Header { get; }
     }
 }

src/CorrelationId/CorrelationContextAccessor.cs

@@ -7,6 +7,7 @@ public class CorrelationContextAccessor : ICorrelationContextAccessor
     {
         private static AsyncLocal<CorrelationContext> _correlationContext = new AsyncLocal<CorrelationContext>();
 
+        /// <inheritdoc />
         public CorrelationContext CorrelationContext
         {
             get => _correlationContext.Value;

src/CorrelationId/CorrelationContextFactory.cs

@@ -4,16 +4,27 @@
     public class CorrelationContextFactory : ICorrelationContextFactory
     {
         private readonly ICorrelationContextAccessor _correlationContextAccessor;
-
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="T:CorrelationId.CorrelationContextFactory" /> class.
+        /// </summary>
+        public CorrelationContextFactory() 
+            : this(null)
+        { }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CorrelationContextFactory"/> class.
+        /// </summary>
+        /// <param name="correlationContextAccessor">The <see cref="ICorrelationContextAccessor"/> through which the <see cref="CorrelationContext"/> will be set.</param>
         public CorrelationContextFactory(ICorrelationContextAccessor correlationContextAccessor)
         {
             _correlationContextAccessor = correlationContextAccessor;
         }
 
         /// <inheritdoc />
-        public CorrelationContext Create(string correlationId)
+        public CorrelationContext Create(string correlationId, string header)
         {
-            var correlationContext = new CorrelationContext(correlationId);
+            var correlationContext = new CorrelationContext(correlationId, header);
 
             if (_correlationContextAccessor != null)
             {

src/CorrelationId/CorrelationId.csproj

@@ -11,12 +11,20 @@
     <RepositoryType>git</RepositoryType>
     <PackageTags>aspnetcore;correlationid</PackageTags>
     <NeutralLanguage>en</NeutralLanguage>
-    <Version>2.0.1</Version>
+    <Version>2.1.0</Version>
     <DocumentationFile>bin\Release\netstandard1.4\CorrelationId.xml</DocumentationFile>
     <PackageProjectUrl>https://github.com/stevejgordon/CorrelationId</PackageProjectUrl>
     <RepositoryUrl>https://github.com/stevejgordon/CorrelationId</RepositoryUrl>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Http.Abstractions" Version="1.0.0" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="1.0.0" />

src/CorrelationId/CorrelationIdMiddleware.cs

@@ -2,13 +2,18 @@
 using Microsoft.Extensions.Options;
 using System;
 using System.Threading.Tasks;
+using Microsoft.Extensions.Primitives;
 
 namespace CorrelationId
 {
+    /// <summary>
+    /// Middleware which attempts to reads / creates a Correlation ID that can then be used in logs and 
+    /// passed to upstream requests.
+    /// </summary>
     public class CorrelationIdMiddleware
     {
         private readonly RequestDelegate _next;
-        private readonly IOptions<CorrelationIdOptions> _options;
+        private readonly CorrelationIdOptions _options;
 
         /// <summary>
         /// Creates a new instance of the CorrelationIdMiddleware.
@@ -18,7 +23,7 @@ public class CorrelationIdMiddleware
         public CorrelationIdMiddleware(RequestDelegate next, IOptions<CorrelationIdOptions> options)
         {
             _next = next ?? throw new ArgumentNullException(nameof(next));
-            _options = options ?? throw new ArgumentNullException(nameof(options));
+            _options = options.Value ?? throw new ArgumentNullException(nameof(options));
         }
 
         /// <summary>
@@ -27,26 +32,25 @@ public CorrelationIdMiddleware(RequestDelegate next, IOptions<CorrelationIdOptio
         /// </summary>
         /// <param name="context">The <see cref="HttpContext"/> for the current request.</param>
         /// <param name="correlationContextFactory">The <see cref="ICorrelationContextFactory"/> which can create a <see cref="CorrelationContext"/>.</param>
-        /// <returns></returns>
         public async Task Invoke(HttpContext context, ICorrelationContextFactory correlationContextFactory)
         {
-            if (context.Request.Headers.TryGetValue(_options.Value.Header, out var correlationId))
-            {
+            var correlationId = SetCorrelationId(context);
+
+            if (_options.UpdateTraceIdentifier)
                 context.TraceIdentifier = correlationId;
-            }
 
-            correlationContextFactory.Create(context.TraceIdentifier);
+            correlationContextFactory.Create(correlationId, _options.Header);
 
-            if (_options.Value.IncludeInResponse)
+            if (_options.IncludeInResponse)
             {
                 // apply the correlation ID to the response header for client side tracking
                 context.Response.OnStarting(() =>
                 {
-                    if (!context.Response.Headers.ContainsKey(_options.Value.Header))
+                    if (!context.Response.Headers.ContainsKey(_options.Header))
                     {
-                        context.Response.Headers.Add(_options.Value.Header, context.TraceIdentifier);
+                        context.Response.Headers.Add(_options.Header, correlationId);
                     }
-                   
+
                     return Task.CompletedTask;
                 });
             }
@@ -55,5 +59,21 @@ public async Task Invoke(HttpContext context, ICorrelationContextFactory correla
 
             correlationContextFactory.Dispose();
         }
+
+        private StringValues SetCorrelationId(HttpContext context)
+        {
+            var correlationIdFoundInRequestHeader = context.Request.Headers.TryGetValue(_options.Header, out var correlationId);
+
+            if (RequiresGenerationOfCorrelationId(correlationIdFoundInRequestHeader, correlationId))
+                correlationId = GenerateCorrelationId(context.TraceIdentifier);
+
+            return correlationId;
+        }
+
+        private static bool RequiresGenerationOfCorrelationId(bool idInHeader, StringValues idFromHeader) => 
+            !idInHeader || StringValues.IsNullOrEmpty(idFromHeader);
+
+        private StringValues GenerateCorrelationId(string traceIdentifier) => 
+            _options.UseGuidForCorrelationId || string.IsNullOrEmpty(traceIdentifier) ? Guid.NewGuid().ToString() : traceIdentifier;
     }
 }

src/CorrelationId/CorrelationIdOptions.cs

@@ -8,13 +8,33 @@ public class CorrelationIdOptions
         private const string DefaultHeader = "X-Correlation-ID";
 
         /// <summary>
-        /// The header field name where the correlation ID will be stored.
+        /// The name of the header from which the Correlation ID is read/written.
         /// </summary>
         public string Header { get; set; } = DefaultHeader;
 
         /// <summary>
+        /// <para>
         /// Controls whether the correlation ID is returned in the response headers.
+        /// </para>
+        /// <para>Default: true</para>
         /// </summary>
         public bool IncludeInResponse { get; set; } = true;
+
+        /// <summary>
+        /// <para>
+        /// Controls whether the ASP.NET Core TraceIdentifier will be set to match the CorrelationId.
+        /// </para>
+        /// <para>Default: true</para>
+        /// </summary>
+        public bool UpdateTraceIdentifier { get; set; } = true;
+
+        /// <summary>
+        /// <para>
+        /// Controls whether a GUID will be used in cases where no correlation ID is retrieved from the request header.
+        /// When false the TraceIdentifier for the current request will be used.
+        /// </para>
+        /// <para> Default: false.</para>
+        /// </summary>
+        public bool UseGuidForCorrelationId { get; set; } = false;
     }
 }

src/CorrelationId/CorrelationIdServiceExtensions.cs

@@ -3,6 +3,9 @@
 
 namespace CorrelationId
 {
+    /// <summary>
+    /// Extensions on the <see cref="IServiceCollection"/>.
+    /// </summary>
     public static class CorrelationIdServiceExtensions
     {
         /// <summary>

src/CorrelationId/ICorrelationContextFactory.cs

@@ -9,8 +9,9 @@ public interface ICorrelationContextFactory
         /// Creates a new <see cref="CorrelationContext"/> with the correlation ID set for the current request.
         /// </summary>
         /// <param name="correlationId">The correlation ID to set on the context.</param>
+        /// /// <param name="header">The header used to hold the correlation ID.</param>
         /// <returns>A new instance of a <see cref="CorrelationContext"/>.</returns>
-        CorrelationContext Create(string correlationId);
+        CorrelationContext Create(string correlationId, string header);
 
         /// <summary>
         /// Disposes of the <see cref="CorrelationContext"/> for the current request.