Update default value of DD_LOGS_INJECTION to true (#7336)

## Summary of changes
- updates the default value of DD_LOGS_INJECTION to be true
- this change will enable log injection for structured logging
frameworks by default

## Reason for change
- Phase 1 of Trace Log Correlation
[RFC](https://docs.google.com/document/d/1Okl7hQcJgA9NdQ8msSVu5P2cPQOx139K9s9f3C_bTho/edit?tab=t.0)

## Implementation details

## Test coverage

## Other details
<!-- Fixes #{issue} -->


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---------

Co-authored-by: Zach Montoya <[email protected]>

Author: rachelyangdog

tracer/build/_build/Build.ExplorationTests.cs

@@ -166,7 +166,9 @@ Dictionary<string, string> GetEnvironmentVariables(ExplorationTestDescription te
         {
             ["DD_TRACE_LOG_DIRECTORY"] = TestLogsDirectory,
             ["DD_SERVICE"] = "exploration_tests",
-            ["DD_VERSION"] = Version
+            ["DD_VERSION"] = Version,
+            // Disable logs injection for exploration tests to avoid interfering with third-party test expectations
+            ["DD_LOGS_INJECTION"] = "false"
         };
 
         switch (ExplorationTestUseCase)

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/ManualInstrumentation/Configuration/TracerSettings/PopulateDictionaryIntegration.cs

@@ -58,7 +58,7 @@ internal static void PopulateSettings(Dictionary<string, object?> values, Trace.
         values[TracerSettingKeyConstants.HeaderTags] = settings.HeaderTags;
         values[TracerSettingKeyConstants.KafkaCreateConsumerScopeEnabledKey] = settings.KafkaCreateConsumerScopeEnabled;
 #pragma warning disable DD0002 // This API is only for public usage and should not be called internally (there's no internal version currently)
-        values[TracerSettingKeyConstants.LogsInjectionEnabledKey] = settings.LogSubmissionSettings.LogsInjectionEnabled;
+        values[TracerSettingKeyConstants.LogsInjectionEnabledKey] = settings.LogsInjectionEnabled;
 #pragma warning restore DD0002
         values[TracerSettingKeyConstants.MaxTracesSubmittedPerSecondKey] = settings.MaxTracesSubmittedPerSecond;
         values[TracerSettingKeyConstants.ServiceNameKey] = settings.ServiceName;

tracer/src/Datadog.Trace/Configuration/TracerSettings.cs

@@ -52,6 +52,7 @@ public record TracerSettings
         // These values can all be overwritten by dynamic config
         private readonly bool _traceEnabled;
         private readonly bool _apmTracingEnabled;
+        private readonly bool _logsInjectionEnabled;
         private readonly bool _isDataStreamsMonitoringEnabled;
         private readonly bool _isDataStreamsMonitoringInDefaultState;
         private readonly ReadOnlyDictionary<string, string> _headerTags;
@@ -302,6 +303,10 @@ internal TracerSettings(IConfigurationSource? source, IConfigurationTelemetry te
                                       .WithKeys(ConfigurationKeys.ApmTracingEnabled)
                                       .AsBool(defaultValue: true);
 
+            _logsInjectionEnabled = config
+                                         .WithKeys(ConfigurationKeys.LogsInjectionEnabled)
+                                         .AsBool(defaultValue: true);
+
             if (AzureAppServiceMetadata?.IsUnsafeToTrace == true)
             {
                 telemetry.Record(ConfigurationKeys.TraceEnabled, false, ConfigurationOrigins.Calculated);
@@ -910,11 +915,10 @@ static void RecordDisabledIntegrationsTelemetry(IntegrationSettingsCollection in
         /// <summary>
         /// Gets a value indicating whether correlation identifiers are
         /// automatically injected into the logging context.
-        /// Default is <c>false</c>, unless <see cref="ConfigurationKeys.DirectLogSubmission.EnabledIntegrations"/>
-        /// enables Direct Log Submission.
+        /// Default is <c>true</c>.
         /// </summary>
         /// <seealso cref="ConfigurationKeys.LogsInjectionEnabled"/>
-        public bool LogsInjectionEnabled => DynamicSettings.LogsInjectionEnabled ?? LogSubmissionSettings.LogsInjectionEnabled;
+        public bool LogsInjectionEnabled => DynamicSettings.LogsInjectionEnabled ?? _logsInjectionEnabled;
 
         /// <summary>
         /// Gets a value indicating the maximum number of traces set to AutoKeep (p1) per second.

tracer/src/Datadog.Trace/Logging/DirectSubmission/DirectLogSubmissionSettings.cs

@@ -169,9 +169,6 @@ public DirectLogSubmissionSettings(IConfigurationSource? source, IConfigurationT
 
             ValidationErrors = validationErrors;
             IsEnabled = isEnabled;
-
-            // Logs injection is enabled by default if direct log submission is enabled, otherwise disabled by default
-            LogsInjectionEnabled = config.WithKeys(ConfigurationKeys.LogsInjectionEnabled).AsBool(defaultValue: isEnabled);
         }
 
         /// <summary>
@@ -238,11 +235,6 @@ public DirectLogSubmissionSettings(IConfigurationSource? source, IConfigurationT
         /// </summary>
         internal string ApiKey { get; }
 
-        /// <summary>
-        /// Gets or sets a value indicating whether logs injection is enabled or disabled
-        /// </summary>
-        internal bool LogsInjectionEnabled { get; set; }
-
         public IEnumerable<string> EnabledIntegrationNames
             => SupportedIntegrations.Where(x => _enabledIntegrations?[(int)x] == true).Select(x => IntegrationRegistry.GetName(x));
 

tracer/test/Datadog.Trace.ClrProfiler.IntegrationTests/Log4NetTests.cs

@@ -74,7 +74,6 @@ public static System.Collections.Generic.IEnumerable<object[]> GetTestData()
         public async Task InjectsLogsWhenEnabled(string packageVersion, bool enableLogShipping, bool enable128BitInjection)
         {
             SetInstrumentationVerification();
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
             SetEnvironmentVariable("DD_TRACE_128_BIT_TRACEID_LOGGING_ENABLED", enable128BitInjection ? "true" : "false");
             using var logsIntake = new MockLogsIntake();
             if (enableLogShipping)
@@ -197,7 +196,6 @@ public async Task DirectlyShipsLogs(string packageVersion)
             using var logsIntake = new MockLogsIntake();
 
             SetInstrumentationVerification();
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
             SetEnvironmentVariable("INCLUDE_CROSS_DOMAIN_CALL", "false");
             EnableDirectLogSubmission(logsIntake.Port, nameof(IntegrationId.Log4Net), hostName);
 

tracer/test/Datadog.Trace.ClrProfiler.IntegrationTests/NLogTests.cs

@@ -271,7 +271,6 @@ public static IEnumerable<object[]> DoesNotInjectLogsWhenDisabledTestData()
         [Trait("SupportsInstrumentationVerification", "True")]
         public async Task InjectsLogsWhenEnabled(string packageVersion, DirectLogSubmission enableLogShipping, string context, ConfigurationType configType, Enable128BitInjection enable128BitInjection)
         {
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
             SetEnvironmentVariable("DD_TRACE_128_BIT_TRACEID_LOGGING_ENABLED", enable128BitInjection == Enable128BitInjection.Enable ? "true" : "false");
             SetInstrumentationVerification();
             using var logsIntake = new MockLogsIntake();

tracer/test/Datadog.Trace.ClrProfiler.IntegrationTests/SerilogTests.cs

@@ -125,7 +125,6 @@ public async Task DirectlyShipsLogs_Pre_2_12_0(
 
         private async Task InjectsLogsWhenEnabledBase(string packageVersion, bool enableLogShipping, bool loadFromConfig, bool enable128BitInjection)
         {
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
             SetEnvironmentVariable("DD_TRACE_128_BIT_TRACEID_LOGGING_ENABLED", enable128BitInjection ? "true" : "false");
             SetSerilogConfiguration(loadFromConfig);
             SetInstrumentationVerification();
@@ -184,7 +183,6 @@ private async Task DirectlyShipsLogsBase(string packageVersion, bool loadFromCon
 
             SetInstrumentationVerification();
             SetSerilogConfiguration(loadFromConfig);
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
             SetEnvironmentVariable("INCLUDE_CROSS_DOMAIN_CALL", "false");
             SetEnvironmentVariable("DD_TRACE_128_BIT_TRACEID_LOGGING_ENABLED", enable128BitInjection ? "true" : "false");
             EnableDirectLogSubmission(logsIntake.Port, nameof(IntegrationId.Serilog), hostName);

tracer/test/Datadog.Trace.ClrProfiler.IntegrationTests/VersionConflict/ILoggerVersionConflict2xTests.cs

@@ -29,7 +29,6 @@ public ILoggerVersionConflict2xTests(ITestOutputHelper output)
             : base(output, "LogsInjection.ILogger.VersionConflict.2x")
         {
             SetServiceVersion("1.0.0");
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
 
             // When doing log injection for CI, only emit 64-bit trace-ids.
             // By default, the version conflict results in both 64-bit trace-ids

tracer/test/Datadog.Trace.ClrProfiler.IntegrationTests/VersionConflict/Log4NetVersionConflict2xTests.cs

@@ -42,8 +42,6 @@ public Log4NetVersionConflict2xTests(ITestOutputHelper output)
         [Trait("RunOnWindows", "True")]
         public async Task InjectsLogsWhenEnabled()
         {
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
-
             var expectedCorrelatedTraceCount = 1;
             var expectedCorrelatedSpanCount = 8;
 

tracer/test/Datadog.Trace.ClrProfiler.IntegrationTests/VersionConflict/NLog10VersionConflict2xTests.cs

@@ -35,8 +35,6 @@ public NLog10VersionConflict2xTests(ITestOutputHelper output)
         [Trait("RunOnWindows", "True")]
         public async Task InjectsLogsWhenEnabled()
         {
-            SetEnvironmentVariable("DD_LOGS_INJECTION", "true");
-
             var expectedCorrelatedTraceCount = 1;
             var expectedCorrelatedSpanCount = 8;