Update docs for entrypoints

Author: sginji

docs/sdk/entry_points.rst

@@ -0,0 +1,77 @@
+Entry Points
+============
+
+OpenTelemetry Python uses Python's **entry points** mechanism to provide a pluggable architecture. Entry points allow you to register custom components (exporters, samplers, etc.) that can be discovered and loaded at runtime.
+
+Configuration
+-------------
+
+Entry points are controlled via environment variables:
+
+* ``OTEL_TRACES_EXPORTER`` - Trace exporters (e.g., ``console``, ``otlp_proto_grpc``)
+* ``OTEL_METRICS_EXPORTER`` - Metrics exporters (e.g., ``console``, ``prometheus``)  
+* ``OTEL_LOGS_EXPORTER`` - Log exporters (e.g., ``console``, ``otlp_proto_http``)
+* ``OTEL_TRACES_SAMPLER`` - Trace samplers (e.g., ``always_on``, ``traceidratio``)
+* ``OTEL_PROPAGATORS`` - Context propagators (e.g., ``tracecontext,baggage``)
+
+Available Entry Point Groups
+----------------------------
+
+**Exporters** - Send telemetry data to backends:
+
+* ``opentelemetry_traces_exporter`` - Trace exporters
+* ``opentelemetry_metrics_exporter`` - Metrics exporters  
+* ``opentelemetry_logs_exporter`` - Log exporters
+
+**Configuration** - Control telemetry behavior:
+
+* ``opentelemetry_traces_sampler`` - Decide which traces to collect
+* ``opentelemetry_id_generator`` - Generate trace/span IDs
+* ``opentelemetry_resource_detector`` - Detect environment info
+
+**Context** - Manage distributed tracing context:
+
+* ``opentelemetry_propagator`` - Cross-service context propagation
+* ``opentelemetry_context`` - Context storage mechanism
+
+**Providers** - Core telemetry factories:
+
+* ``opentelemetry_tracer_provider`` - Create tracers
+* ``opentelemetry_meter_provider`` - Create meters
+* ``opentelemetry_logger_provider`` - Create loggers
+
+Creating a Custom Exporter
+---------------------------
+
+1. **Create your exporter class**:
+
+.. code-block:: python
+
+   from opentelemetry.sdk.trace.export import SpanExporter
+   
+   class MyExporter(SpanExporter):
+       def export(self, spans):
+           # Your export logic here
+           for span in spans:
+               print(f"Exporting: {span.name}")
+
+2. **Register in pyproject.toml**:
+
+.. code-block:: toml
+
+   [project.entry-points.opentelemetry_traces_exporter]
+   my_exporter = "mypackage.exporters:MyExporter"
+
+3. **Use it**:
+
+.. code-block:: bash
+
+   export OTEL_TRACES_EXPORTER=my_exporter
+   python your_app.py
+
+See Also
+--------
+
+* :doc:`trace` - Trace SDK documentation
+* :doc:`metrics` - Metrics SDK documentation  
+* :doc:`environment_variables` - Environment variable reference 

docs/sdk/index.rst

@@ -12,3 +12,4 @@ OpenTelemetry Python SDK
     metrics
     error_handler
     environment_variables
+    entry_points