Azure functions overwite discover default service name

docs/configuration.asciidoc

@@ -135,6 +135,29 @@ The service must then be restarted for the change to take effect
 Restart-Service <service-name>
 ----
 
+[[configuration-for-azure-functions]]
+=== Configuration for Azure Functions
+Configuration for Azure Functions can be provided by setting environment variables for
+the specific Azure Functions using https://learn.microsoft.com/en-us/azure/azure-functions/functions-how-to-use-azure-function-app-settings?tabs=portal#settings[application settings in the Azure Portal].
+
+[float]
+[[config-overwritediscoverdefaultservicename]]
+==== `Enabled` (added[1.27.0])
+
+Setting this to `false` keeps the discover default service name. Else, the discover default service name is replaced by the Azure Functions name.
+
+[options="header"]
+|============
+| Environment variable name       | IConfiguration or Web.config key
+| `ELASTIC_APM_OVERWRITE_DISCOVER_DEFAULT_SERVICE_NAME`           | `ElasticApm:OverwriteDiscoverDefaultServiceName`
+|============
+
+[options="header"]
+|============
+| Default        | Type
+| `true`         | Boolean
+|============
+
 [[configuration-on-asp-net]]
 === Configuration on ASP.NET
 

src/Elastic.Apm/BackendComm/CentralConfig/RuntimeConfigurationSnapshot.cs

@@ -73,6 +73,9 @@ public ConfigurationKeyValue Lookup(ConfigurationOption option) =>
 		public int MaxQueueEventCount => _mainConfiguration.MaxQueueEventCount;
 
 		public double MetricsIntervalInMilliseconds => _mainConfiguration.MetricsIntervalInMilliseconds;
+
+		public bool OverwriteDiscoverDefaultServiceName => _mainConfiguration.OverwriteDiscoverDefaultServiceName;
+
 		public bool Recording => _dynamicConfiguration?.Recording ?? _mainConfiguration.Recording;
 
 		public IReadOnlyList<WildcardMatcher> SanitizeFieldNames => _dynamicConfiguration?.SanitizeFieldNames ?? _mainConfiguration.SanitizeFieldNames;

src/Elastic.Apm/Config/ConfigConsts.cs

@@ -36,6 +36,7 @@ public static class DefaultValues
 			public const int MaxQueueEventCount = 1000;
 			public const string MetricsInterval = "30s";
 			public const double MetricsIntervalInMilliseconds = 30 * 1000;
+			public const bool OverwriteDiscoverDefaultServiceName = true;
 			public const bool SpanCompressionEnabled = true;
 			public const string SpanCompressionExactMatchMaxDuration = "50ms";
 			public const double SpanCompressionExactMatchMaxDurationInMilliseconds = 50;

src/Elastic.Apm/Config/ConfigurationOption.cs

@@ -56,6 +56,8 @@ public enum ConfigurationOption
 		MaxQueueEventCount,
 		/// <inheritdoc cref="IConfigurationReader.MetricsIntervalInMilliseconds"/>
 		MetricsInterval,
+		/// <inheritdoc cref="IConfigurationReader.OverwriteDiscoverDefaultServiceName"/>
+		OverwriteDiscoverDefaultServiceName,
 		/// <inheritdoc cref="IConfigurationReader.Recording"/>
 		Recording,
 		/// <inheritdoc cref="IConfigurationReader.SanitizeFieldNames"/>
@@ -160,6 +162,7 @@ public static string ToEnvironmentVariable(this ConfigurationOption option) =>
 				MaxBatchEventCount => EnvPrefix + "MAX_BATCH_EVENT_COUNT",
 				MaxQueueEventCount => EnvPrefix + "MAX_QUEUE_EVENT_COUNT",
 				MetricsInterval => EnvPrefix + "METRICS_INTERVAL",
+				OverwriteDiscoverDefaultServiceName => EnvPrefix + "OVERWRITE_DISCOVER_DEFAULT_SERVICE_NAME",
 				Recording => EnvPrefix + "RECORDING",
 				SanitizeFieldNames => EnvPrefix + "SANITIZE_FIELD_NAMES",
 				SecretToken => EnvPrefix + "SECRET_TOKEN",
@@ -212,6 +215,7 @@ public static string ToConfigKey(this ConfigurationOption option) =>
 				MaxBatchEventCount => KeyPrefix + nameof(MaxBatchEventCount),
 				MaxQueueEventCount => KeyPrefix + nameof(MaxQueueEventCount),
 				MetricsInterval => KeyPrefix + nameof(MetricsInterval),
+				OverwriteDiscoverDefaultServiceName => KeyPrefix + nameof(OverwriteDiscoverDefaultServiceName),
 				Recording => KeyPrefix + nameof(Recording),
 				SanitizeFieldNames => KeyPrefix + nameof(SanitizeFieldNames),
 				SecretToken => KeyPrefix + nameof(SecretToken),

src/Elastic.Apm/Config/FallbackToEnvironmentConfigurationBase.cs

@@ -104,6 +104,7 @@ IConfigurationEnvironmentValueProvider environmentValueProvider
 			MaxBatchEventCount = ParseMaxBatchEventCount(Lookup(ConfigurationOption.MaxBatchEventCount));
 			MaxQueueEventCount = ParseMaxQueueEventCount(Lookup(ConfigurationOption.MaxQueueEventCount));
 			MetricsIntervalInMilliseconds = ParseMetricsInterval(Lookup(MetricsInterval));
+			OverwriteDiscoverDefaultServiceName = ParseRecording(Lookup(ConfigurationOption.OverwriteDiscoverDefaultServiceName));
 			Recording = ParseRecording(Lookup(ConfigurationOption.Recording));
 			SanitizeFieldNames = ParseSanitizeFieldNames(Lookup(ConfigurationOption.SanitizeFieldNames));
 			SecretToken = ParseSecretToken(Lookup(ConfigurationOption.SecretToken));
@@ -195,6 +196,8 @@ public ConfigurationKeyValue Lookup(ConfigurationOption option) =>
 
 		public double MetricsIntervalInMilliseconds { get; }
 
+		public bool OverwriteDiscoverDefaultServiceName { get; }
+
 		public bool Recording { get; }
 
 		public IReadOnlyList<WildcardMatcher> SanitizeFieldNames { get; }

src/Elastic.Apm/Config/IConfigurationReader.cs

@@ -219,6 +219,14 @@ public interface IConfigurationReader : IConfigurationDescription, IConfiguratio
 
 		double MetricsIntervalInMilliseconds { get; }
 
+		/// <summary>
+		/// Overwrite the discover default service name by the Azure Functions name.
+		/// </summary>
+		/// <remarks>
+		/// This option is only used during the setup of Azure Functions agent
+		/// </remarks>
+		bool OverwriteDiscoverDefaultServiceName { get; }
+
 		/// <summary>
 		/// Whether the agent is recording.
 		/// When set to <c>true</c>. the agent instruments and capture requests, tracks errors, and

src/azure/Elastic.Apm.Azure.Functions/AzureFunctionsContext.cs

@@ -18,7 +18,7 @@ internal AzureFunctionsContext(string loggerScopeName)
 	{
 		Logger = Agent.Instance.Logger.Scoped(loggerScopeName);
 		MetaData = AzureFunctionsMetadataProvider.GetAzureFunctionsMetaData(Logger);
-		UpdateServiceInformation(Agent.Instance.Service);
+		UpdateServiceInformation(Agent.Instance.Service, Agent.Instance.Configuration.OverwriteDiscoverDefaultServiceName);
 		FaasIdPrefix =
 			$"/subscriptions/{MetaData.SubscriptionId}/resourceGroups/{MetaData.WebsiteResourceGroup}/providers/Microsoft.Web/sites/{MetaData.WebsiteSiteName}/functions/";
 		Logger.Trace()?.Log("FaasIdPrefix: {FaasIdPrefix}", FaasIdPrefix);
@@ -32,15 +32,15 @@ internal AzureFunctionsContext(string loggerScopeName)
 
 	internal static bool IsColdStart() => Interlocked.Exchange(ref ColdStart, 0) == 1;
 
-	private void UpdateServiceInformation(Service? service)
+	private void UpdateServiceInformation(Service? service, bool overwriteDiscoverDefaultServiceName)
 	{
 		if (service == null)
 		{
 			Logger.Warning()?.Log($"{nameof(UpdateServiceInformation)}: service is null");
 			return;
 		}
 
-		if (service.Name == AbstractConfigurationReader.AdaptServiceName(AbstractConfigurationReader.DiscoverDefaultServiceName()))
+		if (overwriteDiscoverDefaultServiceName && service.Name == AbstractConfigurationReader.AdaptServiceName(AbstractConfigurationReader.DiscoverDefaultServiceName()))
 		{
 			// Only override the service name if it was set to default.
 			service.Name = MetaData.WebsiteSiteName;

test/Elastic.Apm.Tests.Utilities/MockConfiguration.cs

@@ -68,7 +68,8 @@ public MockConfiguration(IApmLogger logger = null,
 			string spanCompressionEnabled = null,
 			string spanCompressionExactMatchMaxDuration = null,
 			string spanCompressionSameKindMaxDuration = null,
-			string traceContinuationStrategy = null
+			string traceContinuationStrategy = null,
+			string overwritediscoverdefaultservicename = null
 		) : base(
 			logger,
 			new ConfigurationDefaults { DebugName = nameof(MockConfiguration) },
@@ -97,6 +98,7 @@ public MockConfiguration(IApmLogger logger = null,
 				ConfigurationOption.MaxBatchEventCount => maxBatchEventCount,
 				ConfigurationOption.MaxQueueEventCount => maxQueueEventCount,
 				ConfigurationOption.MetricsInterval => metricsInterval,
+				ConfigurationOption.OverwriteDiscoverDefaultServiceName => overwritediscoverdefaultservicename,
 				ConfigurationOption.Recording => recording,
 				ConfigurationOption.SanitizeFieldNames => sanitizeFieldNames,
 				ConfigurationOption.SecretToken => secretToken,

test/Elastic.Apm.Tests/Config/ConfigTests.cs

@@ -1157,6 +1157,43 @@ public void DefaultApplicationNamespaceConfig()
 			excludedNamespaces.Should().BeEquivalentTo(DefaultValues.DefaultExcludedNamespaces);
 		}
 
+		/// <summary>
+		/// Makes sure that in case OverwriteDiscoverDefaultServiceName is not set, the agent uses true as default value
+		/// </summary>
+		[Fact]
+		public void OverwriteDiscoverDefaultServiceNameTestWithNoValue()
+		{
+			using var agent =
+				new ApmAgent(new TestAgentComponents(
+					configuration: new MockConfiguration()));
+			agent.Configuration.OverwriteDiscoverDefaultServiceName.Should().BeTrue();
+		}
+
+		/// <summary>
+		/// Makes sure that in case OverwriteDiscoverDefaultServiceName is set to invalid value, the agent uses true as default value
+		/// </summary>
+		[Fact]
+		public void OverwriteDiscoverDefaultServiceNameTestWithInvalidValue()
+		{
+			using var agent =
+				new ApmAgent(new TestAgentComponents(
+					configuration: new MockConfiguration(overwritediscoverdefaultservicename: "foobar")));
+			agent.Configuration.OverwriteDiscoverDefaultServiceName.Should().BeTrue();
+		}
+
+		[Theory]
+		[InlineData("true", true)]
+		[InlineData("false", false)]
+		[InlineData("True", true)]
+		[InlineData("False", false)]
+		[InlineData("       True         ", true)]
+		[InlineData("       False        ", false)]
+		public void OverwriteDiscoverDefaultServiceNameTestWithValidValue(string value, bool expected)
+		{
+			using var agent = new ApmAgent(new TestAgentComponents(configuration: new MockConfiguration(overwritediscoverdefaultservicename: value)));
+			agent.Configuration.OverwriteDiscoverDefaultServiceName.Should().Be(expected);
+		}
+
 		private static double MetricsIntervalTestCommon(string configValue)
 		{
 			Environment.SetEnvironmentVariable(MetricsInterval.ToEnvironmentVariable(), configValue);

test/Elastic.Apm.Tests/ConstructorTests.cs

@@ -104,6 +104,7 @@ private class LogConfiguration : IConfiguration, IConfigurationDescription
 		public int MaxBatchEventCount => ConfigConsts.DefaultValues.MaxBatchEventCount;
 		public int MaxQueueEventCount => ConfigConsts.DefaultValues.MaxQueueEventCount;
 		public double MetricsIntervalInMilliseconds => ConfigConsts.DefaultValues.MetricsIntervalInMilliseconds;
+		public bool OverwriteDiscoverDefaultServiceName => ConfigConsts.DefaultValues.OverwriteDiscoverDefaultServiceName;
 		public string SecretToken { get; }
 		public string ServerCert { get; }
 		public string ApiKey { get; }

test/azure/Elastic.Apm.Azure.Functions.Tests/AzureFunctionsIsolatedNotOverwriteTests.cs

@@ -0,0 +1,29 @@
+// Licensed to Elasticsearch B.V under one or more agreements.
+// Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information
+
+using System.Threading.Tasks;
+using FluentAssertions;
+using Xunit;
+using Xunit.Abstractions;
+using static Elastic.Apm.Api.Outcome;
+using static Elastic.Apm.AzureFunctionApp.Core.FunctionName;
+
+namespace Elastic.Apm.Azure.Functions.Tests;
+
+[Collection("AzureFunctions")]
+public class AzureFunctionsIsolatedNotOverwriteTests : AzureFunctionsTestBase, IClassFixture<IsolatedContextNotOverwite>
+{
+	public AzureFunctionsIsolatedNotOverwriteTests(ITestOutputHelper output, IsolatedContextNotOverwite context)
+		: base(output, context) { }
+
+	[Fact]
+	public async Task OverwriteDiscoverDefaultServiceName_False()
+	{
+		var transaction = await InvokeAndAssertFunction(SampleHttpTrigger);
+
+		transaction.Outcome.Should().Be(Success);
+		transaction.Result.Should().Be("HTTP 2xx");
+		transaction.Context.Response.StatusCode.Should().Be(200);
+	}
+}

test/azure/Elastic.Apm.Azure.Functions.Tests/AzureFunctionsTestBase.cs

@@ -59,14 +59,22 @@ private void AssertMetaData(MetadataDto metaData)
 		metaData.Service.Agent.ActivationMethod.Should().Be(Consts.ActivationMethodNuGet);
 		metaData.Cloud.Provider.Should().Be("azure");
 		metaData.Cloud.Service.Name.Should().Be("functions");
-		metaData.Service.Name.Should().Be(Context.WebsiteName);
+		AssertServiceName(metaData.Service.Name);
 		metaData.Service.Runtime.Name.Should().Be(Context.RuntimeName);
 		metaData.Service.Framework.Name.Should().Be("Azure Functions");
 		metaData.Service.Framework.Version.Should().Be("4");
 		// TODO - temporarily removing this assertion as we can no longer seem to set this value without causing a host error
 		//metaData.Service.Node.ConfiguredName.Should().Be("20367ea8-70b9-41b4-a552-b2a826b3aa0b");
 	}
 
+	private void AssertServiceName(string name)
+	{
+		if (Context.OverwriteDiscoverDefaultServiceName == null || (bool)Context.OverwriteDiscoverDefaultServiceName)
+			name.Should().Be(Context.WebsiteName);
+		else
+			name.Should().NotBe(Context.WebsiteName);
+	}
+
 	private static void AssertTracing(TransactionDto transaction) =>
 		transaction.TraceId.Should().Be("0af7651916cd43dd8448eb211c80319c");
 

test/azure/Elastic.Apm.Azure.Functions.Tests/AzureFunctionsTestFixture.cs

@@ -25,15 +25,27 @@ public class IsolatedContext : AzureFunctionTestContextBase
 	protected override Uri BaseUri { get; } = new("http://localhost:7071");
 	public override string WebsiteName { get; } = "testfaas";
 	public override string RuntimeName { get; } = "dotnet-isolated";
+	public override bool? OverwriteDiscoverDefaultServiceName { get; } = null;
 
 	public IsolatedContext() : base(FunctionType.Isolated) { }
 }
 
+public class IsolatedContextNotOverwite : AzureFunctionTestContextBase
+{
+	protected override Uri BaseUri { get; } = new("http://localhost:7071");
+	public override string WebsiteName { get; } = "testfaas";
+	public override string RuntimeName { get; } = "dotnet-isolated";
+	public override bool? OverwriteDiscoverDefaultServiceName { get; } = false;
+
+	public IsolatedContextNotOverwite() : base(FunctionType.Isolated) { }
+}
+
 public class InProcessContext : AzureFunctionTestContextBase
 {
 	protected override Uri BaseUri { get; } = new("http://localhost:17073");
 	public override string WebsiteName { get; } = "testfaas";
 	public override string RuntimeName { get; } = "dotnet";
+	public override bool? OverwriteDiscoverDefaultServiceName { get; } = null;
 
 	public InProcessContext() : base(FunctionType.InProcess) { }
 }
@@ -46,6 +58,7 @@ public abstract class AzureFunctionTestContextBase : IDisposable
 	protected abstract Uri BaseUri { get; }
 	public abstract string WebsiteName { get; }
 	public abstract string RuntimeName { get; }
+	public abstract bool? OverwriteDiscoverDefaultServiceName { get; }
 
 	public bool IsFirst { get; internal set; }
 
@@ -85,7 +98,8 @@ internal AzureFunctionTestContextBase(FunctionType functionType)
 				EnvironmentVariables =
 				{
 					["ELASTIC_APM_SERVER_URL"] = $"http://localhost:{port}",
-					["ELASTIC_APM_FLUSH_INTERVAL"] = "0"
+					["ELASTIC_APM_FLUSH_INTERVAL"] = "0",
+					["ELASTIC_APM_OVERWRITE_DISCOVER_DEFAULT_SERVICE_NAME"] = $"{OverwriteDiscoverDefaultServiceName}"
 				},
 				UseShellExecute = false
 			}