Add OverwriteDiscoverDefaultServiceName configuration item

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