Add CI information to User-Agent header (#7103)

Author: martinrrm

src/NuGet.Core/NuGet.Protocol/CIEnvironmentDetector.cs

@@ -0,0 +1,99 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using NuGet.Common;
+
+namespace NuGet.Protocol.Core.Types
+{
+    /// <summary>
+    /// Detects CI/CD environment from environment variables.
+    /// </summary>
+    internal static class CIEnvironmentDetector
+    {
+        /// <summary>
+        /// Detects the CI environment based on environment variables.
+        /// </summary>
+        /// <param name="environmentVariableReader">The environment variable reader to use.</param>
+        /// <returns>A <see cref="string"/> if a CI environment is detected, null otherwise.</returns>
+        internal static string? Detect(IEnvironmentVariableReader environmentVariableReader)
+        {
+            // GitHub Actions
+            if (string.Equals(environmentVariableReader.GetEnvironmentVariable("GITHUB_ACTIONS"), "true", StringComparison.OrdinalIgnoreCase))
+            {
+                return "GitHub Actions";
+            }
+
+            // Azure DevOps
+            if (string.Equals(environmentVariableReader.GetEnvironmentVariable("TF_BUILD"), "true", StringComparison.OrdinalIgnoreCase))
+            {
+                return "Azure DevOps";
+            }
+
+            // AppVeyor
+            if (string.Equals(environmentVariableReader.GetEnvironmentVariable("APPVEYOR"), "true", StringComparison.OrdinalIgnoreCase))
+            {
+                return "AppVeyor";
+            }
+
+            // Travis CI
+            if (string.Equals(environmentVariableReader.GetEnvironmentVariable("TRAVIS"), "true", StringComparison.OrdinalIgnoreCase))
+            {
+                return "Travis CI";
+            }
+
+            // CircleCI
+            if (string.Equals(environmentVariableReader.GetEnvironmentVariable("CIRCLECI"), "true", StringComparison.OrdinalIgnoreCase))
+            {
+                return "CircleCI";
+            }
+
+            // AWS CodeBuild
+            if (!string.IsNullOrEmpty(environmentVariableReader.GetEnvironmentVariable("CODEBUILD_BUILD_ID")))
+            {
+                return "AWS CodeBuild";
+            }
+
+            // Jenkins - requires both BUILD_ID and BUILD_URL
+            if (!string.IsNullOrEmpty(environmentVariableReader.GetEnvironmentVariable("BUILD_ID")) &&
+                !string.IsNullOrEmpty(environmentVariableReader.GetEnvironmentVariable("BUILD_URL")))
+            {
+                return "Jenkins";
+            }
+
+            // Google Cloud Build - requires both BUILD_ID and PROJECT_ID
+            if (!string.IsNullOrEmpty(environmentVariableReader.GetEnvironmentVariable("BUILD_ID")) &&
+                !string.IsNullOrEmpty(environmentVariableReader.GetEnvironmentVariable("PROJECT_ID")))
+            {
+                return "Google Cloud";
+            }
+
+            // TeamCity
+            if (!string.IsNullOrEmpty(environmentVariableReader.GetEnvironmentVariable("TEAMCITY_VERSION")))
+            {
+                return "TeamCity";
+            }
+
+            // JetBrains Space
+            if (!string.IsNullOrEmpty(environmentVariableReader.GetEnvironmentVariable("JB_SPACE_API_URL")))
+            {
+                return "JetBrains Space";
+            }
+
+            // GitLab CI
+
+            if (string.Equals(environmentVariableReader.GetEnvironmentVariable("GITLAB_CI"), "true", StringComparison.OrdinalIgnoreCase))
+            {
+                return "GitLab CI";
+            }
+
+            // Generic CI - must be last as it's the most general
+            if (string.Equals(environmentVariableReader.GetEnvironmentVariable("CI"), "true", StringComparison.OrdinalIgnoreCase))
+            {
+                return "other";
+            }
+
+            return null;
+        }
+    }
+}

src/NuGet.Core/NuGet.Protocol/UserAgentStringBuilder.cs

@@ -8,6 +8,8 @@
 #endif
 using System.Globalization;
 using System.Runtime.InteropServices;
+using System.Text;
+using NuGet.Common;
 using NuGet.Packaging;
 
 namespace NuGet.Protocol.Core.Types
@@ -16,27 +18,38 @@ public class UserAgentStringBuilder
     {
         public static readonly string DefaultNuGetClientName = "NuGet Client V3";
 
-        private const string UserAgentWithOSDescriptionAndVisualStudioSKUTemplate = "{0}/{1} ({2}, {3})";
-        private const string UserAgentWithOSDescriptionTemplate = "{0}/{1} ({2})";
+        private const string UserAgentWithMetadataTemplate = "{0}/{1} ({2})";
         private const string UserAgentTemplate = "{0}/{1}";
 
         private readonly string _clientName;
         private string _vsInfo;
         private string _osInfo;
+        private string _ciInfo;
 
         public UserAgentStringBuilder()
             : this(DefaultNuGetClientName)
         {
         }
 
         public UserAgentStringBuilder(string clientName)
+            : this(clientName, EnvironmentVariableWrapper.Instance)
+        {
+        }
+
+        /// <summary>
+        /// Internal constructor for testing purposes that allows injecting an environment variable reader.
+        /// </summary>
+        /// <param name="clientName">The client name to use in the user agent string.</param>
+        /// <param name="environmentVariableReader">The environment variable reader for CI detection.</param>
+        internal UserAgentStringBuilder(string clientName, IEnvironmentVariableReader environmentVariableReader)
         {
             _clientName = clientName;
 
             // Read the client version from the assembly metadata and normalize it.
             NuGetClientVersion = MinClientVersionUtility.GetNuGetClientVersion().ToNormalizedString();
 
             _osInfo = GetOS();
+            _ciInfo = CIEnvironmentDetector.Detect(environmentVariableReader);
         }
 
         public string NuGetClientVersion { get; }
@@ -59,7 +72,9 @@ public string Build()
                 clientInfo = DefaultNuGetClientName;
             }
 
-            if (string.IsNullOrEmpty(_osInfo))
+            string metadataString = BuildMetadataString();
+
+            if (string.IsNullOrEmpty(metadataString))
             {
                 return string.Format(
                     CultureInfo.InvariantCulture,
@@ -68,25 +83,43 @@ public string Build()
                     NuGetClientVersion);
             }
 
-            if (string.IsNullOrEmpty(_vsInfo))
+            return string.Format(
+                CultureInfo.InvariantCulture,
+                UserAgentWithMetadataTemplate,
+                clientInfo,
+                NuGetClientVersion,
+                metadataString);
+        }
+
+        /// <summary>
+        /// Builds the metadata string for the parentheses section.
+        /// Items are collected in order (OS, CI, VS) and joined with ", ".
+        /// </summary>
+        internal string BuildMetadataString()
+        {
+            var sb = new StringBuilder();
+
+            // OS info
+            if (!string.IsNullOrEmpty(_osInfo))
             {
-                return string.Format(
-                    CultureInfo.InvariantCulture,
-                    UserAgentWithOSDescriptionTemplate,
-                    clientInfo,
-                    NuGetClientVersion,
-                    _osInfo);
+                sb.Append(_osInfo);
             }
-            else
+
+            // CI info (formatted as "CI: {provider}")
+            if (!string.IsNullOrEmpty(_ciInfo))
             {
-                return string.Format(
-                    CultureInfo.InvariantCulture,
-                    UserAgentWithOSDescriptionAndVisualStudioSKUTemplate,
-                    _clientName,
-                    NuGetClientVersion, /* NuGet version */
-                    _osInfo, /* OS version */
-                    _vsInfo);  /* VS SKU + version */
+                if (sb.Length > 0) sb.Append(", ");
+                sb.Append("CI: ").Append(_ciInfo);
             }
+
+            // VS info
+            if (!string.IsNullOrEmpty(_vsInfo))
+            {
+                if (sb.Length > 0) sb.Append(", ");
+                sb.Append(_vsInfo);
+            }
+
+            return sb.ToString();
         }
 
         internal static string GetOS()