Deprecate OpenTracing support (#4659)

Author: Kielek

CHANGELOG.md

@@ -25,6 +25,8 @@ This component adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.h
 
 ### Deprecated
 
+- Deprecate support for `OpenTracing`.
+
 ### Removed
 
 ### Fixed

docs/config.md

@@ -417,7 +417,7 @@ Important environment variables include:
 | Environment variable                                | Description                                                                                                                                                                                                                                                                                                                                                                                        | Default value | Status                                                                                                                            |
 |-----------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|-----------------------------------------------------------------------------------------------------------------------------------|
 | `OTEL_DOTNET_AUTO_TRACES_ENABLED`                   | Enables traces.                                                                                                                                                                                                                                                                                                                                                                                    | `true`        | [Experimental](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/versioning-and-stability.md) |
-| `OTEL_DOTNET_AUTO_OPENTRACING_ENABLED`              | Enables OpenTracing tracer.                                                                                                                                                                                                                                                                                                                                                                        | `false`       | [Experimental](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/versioning-and-stability.md) |
+| `OTEL_DOTNET_AUTO_OPENTRACING_ENABLED`              | Enables OpenTracing tracer.                                                                                                                                                                                                                                                                                                                                                                        | `false`       | [Deprecated](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/versioning-and-stability.md)   |
 | `OTEL_DOTNET_AUTO_LOGS_ENABLED`                     | Enables logs.                                                                                                                                                                                                                                                                                                                                                                                      | `true`        | [Experimental](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/versioning-and-stability.md) |
 | `OTEL_DOTNET_AUTO_METRICS_ENABLED`                  | Enables metrics.                                                                                                                                                                                                                                                                                                                                                                                   | `true`        | [Experimental](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/versioning-and-stability.md) |
 | `OTEL_DOTNET_AUTO_NETFX_REDIRECT_ENABLED`           | Enables automatic redirection of the assemblies used by the automatic instrumentation on the .NET Framework.                                                                                                                                                                                                                                                                                       | `true`        | [Experimental](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/versioning-and-stability.md) |

src/OpenTelemetry.AutoInstrumentation/Configurations/EnvironmentConfigurationTracerHelper.cs

@@ -59,6 +59,7 @@ public static TracerProviderBuilder UseEnvironmentVariables(
 
         if (settings.OpenTracingEnabled)
         {
+            Logger.Warning("OpenTracing is deprecated and it is enabled by the configuration. It will be removed in future versions. Consider migrating to OpenTelemetry API.");
             builder.AddOpenTracingShimSource();
         }