[CI Visibility] Set TracerSettings using a configuration source instead of mutating (#6399)

## Summary of changes

Change how CI Visibility creates its `TracerSettings` object to avoid
mutating settings afterwards

## Reason for change

This stack of changes is about removing duplication (among other things)
in the `TracerSettings` etc related objects. This is _partially_
required in order to remove the "snapshot generator" complexity that was
removed in #6370. Given
`TracerSettings` are not exposed publicly in Datadog.Trace, we want to
move to doing a "one shot" configuring of them, ultimately so that we
can make the object immutable (and remove `ImmutableTracerSettings` and
friends).

## Implementation details

CI Visibility is one of the few places where we mutate settings _after_
creating the `TracerSettings`. This is mostly because there's additional
logic that CI Visibility wants to perform.

Ultimately, the "solution" to that issue in this PR is to move that
logic into the `TracerSettings` constructor. I'm not entirely happy
about it, but it's the only approach I could find that works.

- Add a "dummy" configuration value to a configuration source when
creating the `TracerSettings`. This is used purely as a "switch" to say
"we're in CI Visibility mode".
- We absolutely could just pass this in as a constructor parameter. I
went that route first and then backed away, but can totally be swayed.
- Add an additional configuration source to update settings that we want
to change in CI Vis (e.g. logs injection).
- In the `TracerSettings` ctor, add an additional ignored URL when in CI
Vis mode, modify the default service name (if required) and add an
additional GlobalTag.

## Test coverage

I'd love to have some, but the CI Visibility configuration is kinda all
over the place, so if you have any pointers @tonyredondo I'm all ears...

## Other details

Part of stack 
- #6370
- #6376
- #6385
- #6386
- #6397 
- #6399 👈 This PR
- #6400  
- #6405
- #6408

Author: andrewlock

tracer/src/Datadog.Trace/Ci/CIVisibility.cs

@@ -129,21 +129,6 @@ public static void Initialize()
 
             var tracerSettings = settings.TracerSettings;
             Log.Debug("Setting up the test session name to: {TestSessionName}", settings.TestSessionName);
-
-            // Set the service name if empty
-            if (string.IsNullOrEmpty(tracerSettings.ServiceName))
-            {
-                // Extract repository name from the git url and use it as a default service name.
-                tracerSettings.ServiceName = GetServiceNameFromRepository(CIEnvironmentValues.Instance.Repository);
-                tracerSettings.GlobalTags[CommonTags.UserProvidedTestServiceTag] = "false";
-            }
-            else
-            {
-                tracerSettings.GlobalTags[CommonTags.UserProvidedTestServiceTag] = "true";
-            }
-
-            // Normalize the service name
-            tracerSettings.ServiceName = NormalizerTraceProcessor.NormalizeService(tracerSettings.ServiceName);
             Log.Debug("Setting up the service name to: {ServiceName}", tracerSettings.ServiceName);
 
             // Initialize Tracer
@@ -203,21 +188,6 @@ internal static void InitializeFromRunner(CIVisibilitySettings settings, IDiscov
 
             var tracerSettings = settings.TracerSettings;
             Log.Debug("Setting up the test session name to: {TestSessionName}", settings.TestSessionName);
-
-            // Set the service name if empty
-            if (string.IsNullOrEmpty(tracerSettings.ServiceName))
-            {
-                // Extract repository name from the git url and use it as a default service name.
-                tracerSettings.ServiceName = GetServiceNameFromRepository(CIEnvironmentValues.Instance.Repository);
-                tracerSettings.GlobalTags[CommonTags.UserProvidedTestServiceTag] = "false";
-            }
-            else
-            {
-                tracerSettings.GlobalTags[CommonTags.UserProvidedTestServiceTag] = "true";
-            }
-
-            // Normalize the service name
-            tracerSettings.ServiceName = NormalizerTraceProcessor.NormalizeService(tracerSettings.ServiceName);
             Log.Debug("Setting up the service name to: {ServiceName}", tracerSettings.ServiceName);
 
             // Initialize Tracer

tracer/src/Datadog.Trace/Ci/Configuration/CIVisibilitySettings.cs

@@ -5,6 +5,7 @@
 #nullable enable
 
 using System;
+using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.Linq;
 using System.Runtime.CompilerServices;
@@ -298,32 +299,30 @@ internal void SetDefaultManualInstrumentationSettings()
         }
 
         private TracerSettings InitializeTracerSettings()
-        {
-            var source = GlobalConfigurationSource.CreateDefaultConfigurationSource();
-            var defaultExcludedUrlSubstrings = string.Empty;
-            var configResult = source.GetString(ConfigurationKeys.HttpClientExcludedUrlSubstrings, NullConfigurationTelemetry.Instance, validator: null, recordValue: false);
-            if (configResult is { IsValid: true, Result: { } substrings } && !string.IsNullOrWhiteSpace(substrings))
-            {
-                defaultExcludedUrlSubstrings = substrings + ", ";
-            }
+            => InitializeTracerSettings(GlobalConfigurationSource.CreateDefaultConfigurationSource());
 
-            source.Insert(0, new NameValueConfigurationSource(
-                                      new NameValueCollection
-                                      {
-                                          [ConfigurationKeys.HttpClientExcludedUrlSubstrings] = defaultExcludedUrlSubstrings + "/session/FakeSessionIdForPollingPurposes",
-                                      },
-                                      ConfigurationOrigins.Calculated));
-
-            var tracerSettings = new TracerSettings(source, new ConfigurationTelemetry(), new OverrideErrorLog());
+        // Internal for testing
+        internal TracerSettings InitializeTracerSettings(CompositeConfigurationSource source)
+        {
+            // This is a somewhat hacky way to "tell" TracerSettings that we're running in CI Visibility
+            // There's no doubt various other ways we could flag it based on values we're _already_ extracting,
+            // but we don't want to set up too much interdependence there.
+            var telemetry = new ConfigurationTelemetry();
+            var additionalSource = new Dictionary<string, object?> { { ConfigurationKeys.CIVisibility.IsRunningInCiVisMode, true } };
 
             if (Logs)
             {
-                // Enable the direct log submission
-                tracerSettings.LogSubmissionSettings.DirectLogSubmissionEnabledIntegrations.Add("XUnit");
-                tracerSettings.LogSubmissionSettings.DirectLogSubmissionBatchPeriod = TimeSpan.FromSeconds(1);
+                // fetch the "original" values, and update them with the CI Visibility settings
+                var enabledDirectLogSubmissionIntegrations = new ConfigurationBuilder(source, telemetry)
+                                                            .WithKeys(ConfigurationKeys.DirectLogSubmission.EnabledIntegrations)
+                                                            .AsString();
+                var logIntegrations = enabledDirectLogSubmissionIntegrations + ";XUnit";
+                additionalSource[ConfigurationKeys.DirectLogSubmission.EnabledIntegrations] = logIntegrations;
+                additionalSource[ConfigurationKeys.DirectLogSubmission.BatchPeriodSeconds] = 1;
             }
 
-            return tracerSettings;
+            var newSource = new CompositeConfigurationSource([new DictionaryObjectConfigurationSource(additionalSource), source]);
+            return new TracerSettings(newSource, telemetry, new OverrideErrorLog());
         }
     }
 }

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

@@ -493,6 +493,11 @@ internal static partial class ConfigurationKeys
         /// </summary>
         public static class CIVisibility
         {
+            /// <summary>
+            /// An internal key used to "tell" tracer settings that we're running in CI Visibility mode
+            /// </summary>
+            public const string IsRunningInCiVisMode = "_DD_INTERNAL_IS_RUNNING_IN_CIVISIBILITY";
+
             /// <summary>
             /// Configuration key for enabling or disabling CI Visibility.
             /// Default value is false (disabled).

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

@@ -10,12 +10,15 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Text.RegularExpressions;
+using Datadog.Trace.Ci;
+using Datadog.Trace.Ci.CiEnvironment;
 using Datadog.Trace.ClrProfiler;
 using Datadog.Trace.ClrProfiler.ServerlessInstrumentation;
 using Datadog.Trace.Configuration.ConfigurationSources.Telemetry;
 using Datadog.Trace.Configuration.Telemetry;
 using Datadog.Trace.Logging;
 using Datadog.Trace.Logging.DirectSubmission;
+using Datadog.Trace.Processors;
 using Datadog.Trace.Propagators;
 using Datadog.Trace.Sampling;
 using Datadog.Trace.SourceGenerators;
@@ -87,6 +90,11 @@ internal TracerSettings(IConfigurationSource? source, IConfigurationTelemetry te
             GCPFunctionSettings = new ImmutableGCPFunctionSettings(source, _telemetry);
             IsRunningInGCPFunctions = GCPFunctionSettings.IsGCPFunction;
 
+            // We don't want/need to record this value, so explicitly use null telemetry
+            var isRunningInCiVisibility = new ConfigurationBuilder(source, NullConfigurationTelemetry.Instance)
+                                         .WithKeys(ConfigurationKeys.CIVisibility.IsRunningInCiVisMode)
+                                         .AsBool(false);
+
             LambdaMetadata = LambdaMetadata.Create();
 
             IsRunningInAzureAppService = ImmutableAzureAppServiceSettings.GetIsAzureAppService(source, telemetry);
@@ -124,11 +132,34 @@ _ when x.ToBoolean() is { } boolean => boolean,
                          .AsString();
 
             var otelServiceName = config.WithKeys(ConfigurationKeys.OpenTelemetry.ServiceName).AsStringResult();
-            ServiceName = config
+            var serviceName = config
                                  .WithKeys(ConfigurationKeys.ServiceName, "DD_SERVICE_NAME")
                                  .AsStringResult()
                                  .OverrideWith(in otelServiceName, ErrorLog);
 
+            var isUserProvidedTestServiceTag = true;
+            if (isRunningInCiVisibility)
+            {
+                // Set the service name if not set
+                var ciVisServiceName = serviceName;
+                if (string.IsNullOrEmpty(serviceName))
+                {
+                    // Extract repository name from the git url and use it as a default service name.
+                    ciVisServiceName = CIVisibility.GetServiceNameFromRepository(CIEnvironmentValues.Instance.Repository);
+                    isUserProvidedTestServiceTag = false;
+                }
+
+                // Normalize the service name
+                ciVisServiceName = NormalizerTraceProcessor.NormalizeService(ciVisServiceName);
+                if (ciVisServiceName != serviceName)
+                {
+                    serviceName = ciVisServiceName;
+                    telemetry.Record(ConfigurationKeys.ServiceName, serviceName, recordValue: true, ConfigurationOrigins.Calculated);
+                }
+            }
+
+            ServiceName = serviceName;
+
             ServiceVersion = config
                             .WithKeys(ConfigurationKeys.ServiceVersion)
                             .AsString();
@@ -204,6 +235,11 @@ _ when x.ToBoolean() is { } boolean => boolean,
                                 .Where(kvp => !string.IsNullOrWhiteSpace(kvp.Key) && !string.IsNullOrWhiteSpace(kvp.Value))
                                 .ToDictionary(kvp => kvp.Key.Trim(), kvp => kvp.Value.Trim());
 
+            if (isRunningInCiVisibility)
+            {
+                GlobalTags[Ci.Tags.CommonTags.UserProvidedTestServiceTag] = isUserProvidedTestServiceTag ? "true" : "false";
+            }
+
             var headerTagsNormalizationFixEnabled = config
                                                .WithKeys(ConfigurationKeys.FeatureFlags.HeaderTagsNormalizationFixEnabled)
                                                .AsBool(defaultValue: true);
@@ -481,9 +517,19 @@ _ when x.ToBoolean() is { } boolean => boolean,
                                         IsRunningInAzureAppService ? ImmutableAzureAppServiceSettings.DefaultHttpClientExclusions :
                                         LambdaMetadata is { IsRunningInLambda: true } m ? m.DefaultHttpClientExclusions : string.Empty);
 
+            if (isRunningInCiVisibility)
+            {
+                // always add the additional exclude in ci vis
+                const string fakeSessionEndpoint = "/session/FakeSessionIdForPollingPurposes";
+                urlSubstringSkips = string.IsNullOrEmpty(urlSubstringSkips)
+                                        ? fakeSessionEndpoint
+                                        : $"{urlSubstringSkips},{fakeSessionEndpoint}";
+                telemetry.Record(ConfigurationKeys.HttpClientExcludedUrlSubstrings, urlSubstringSkips, recordValue: true, ConfigurationOrigins.Calculated);
+            }
+
             HttpClientExcludedUrlSubstrings = !string.IsNullOrEmpty(urlSubstringSkips)
                                                   ? TrimSplitString(urlSubstringSkips.ToUpperInvariant(), commaSeparator)
-                                                  : Array.Empty<string>();
+                                                  : [];
 
             DbmPropagationMode = config
                                 .WithKeys(ConfigurationKeys.DbmPropagationMode)

tracer/test/Datadog.Trace.Tests/Telemetry/ConfigurationTests.cs

@@ -23,6 +23,8 @@ public class ConfigurationTests
         // Lambda handler extracts these directly from env var, and no reason to think that will change
         "_DD_EXTENSION_ENDPOINT",
         "_DD_EXTENSION_PATH",
+        // Internal variable just used to "pass" settings to the
+        "_DD_INTERNAL_IS_RUNNING_IN_CIVISIBILITY",
         // mini agent uses this directly from env var, and no reason to think that will change
         "DD_MINI_AGENT_PATH",
         "DD_ENTITY_ID", // Datadog.Trace.Vendors.StatsdClient.StatsdConfig.EntityIdEnvVar (we don't use this, it was just vendored in)