Exporter and Propagator(s) are env var configurable

Author: tammy-baylis-swi

opentelemetry_distro_solarwinds/distro.py

@@ -1,43 +1,87 @@
 """Module to configure OpenTelemetry agent to work with SolarWinds backend"""
 
+import logging
+from os import environ
+from pkg_resources import iter_entry_points
+
 from opentelemetry import trace
-from opentelemetry.baggage.propagation import W3CBaggagePropagator
+from opentelemetry.environment_variables import OTEL_PROPAGATORS, OTEL_TRACES_EXPORTER
 from opentelemetry.instrumentation.distro import BaseDistro
 from opentelemetry.instrumentation.propagators import set_global_response_propagator
 from opentelemetry.propagate import set_global_textmap
 from opentelemetry.propagators.composite import CompositePropagator
 from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import BatchSpanProcessor
-from opentelemetry.trace.propagation.tracecontext import (
-    TraceContextTextMapPropagator,
-)
 
-from opentelemetry_distro_solarwinds.exporter import SolarWindsSpanExporter
-from opentelemetry_distro_solarwinds.propagator import SolarWindsPropagator
 from opentelemetry_distro_solarwinds.response_propagator import SolarWindsTraceResponsePropagator
 from opentelemetry_distro_solarwinds.sampler import ParentBasedSwSampler
 
+logger = logging.getLogger(__name__)
 
 class SolarWindsDistro(BaseDistro):
-    """SolarWinds custom distro for OpenTelemetry agents.
+    """SolarWinds custom distro for OpenTelemetry agents."""
+
+    _DEFAULT_OTEL_EXPORTER = "solarwinds_exporter"
+    _DEFAULT_OTEL_PROPAGATORS = [
+        "tracecontext",
+        "baggage",
+        "solarwinds_propagator",
+    ]
 
-    With this custom distro, the following functionality is introduced:
-        - no functionality added at this time
-    """
     def _configure(self, **kwargs):
-        # Automatically make use of custom SolarWinds sampler
+        # Automatically use custom SolarWinds sampler
         trace.set_tracer_provider(
             TracerProvider(sampler=ParentBasedSwSampler()))
-        # Automatically configure the SolarWinds Span exporter
-        span_exporter = BatchSpanProcessor(SolarWindsSpanExporter())
-        trace.get_tracer_provider().add_span_processor(span_exporter)
-        # Configure a CompositePropagator including SolarWinds
-        set_global_textmap(
-            CompositePropagator([
-                TraceContextTextMapPropagator(),
-                W3CBaggagePropagator(),
-                SolarWindsPropagator()
-            ])
+
+        # Customize Exporter else default to SolarWindsSpanExporter
+        environ_exporter = environ.get(
+            OTEL_TRACES_EXPORTER,
+            self._DEFAULT_OTEL_EXPORTER
         )
+        try:
+            exporter = next(
+                iter_entry_points(
+                    "opentelemetry_traces_exporter",
+                    environ_exporter
+                )).load()()
+        except:
+            logger.exception(
+                "Failed to load configured exporter `%s`", environ_exporter
+            )
+            raise
+
+        span_exporter = BatchSpanProcessor(exporter)
+        trace.get_tracer_provider().add_span_processor(span_exporter)
+
+        # Configure context propagators to always include
+        # tracecontext,baggage,solarwinds -- first and in that order
+        # -- plus any others specified by env var
+        environ_propagators = environ.get(
+            OTEL_PROPAGATORS,
+            ",".join(self._DEFAULT_OTEL_PROPAGATORS)
+        ).split(",")
+        if environ_propagators != self._DEFAULT_OTEL_PROPAGATORS:
+            for default in self._DEFAULT_OTEL_PROPAGATORS:
+                while default in environ_propagators:
+                    environ_propagators.remove(default)
+            environ_propagators = self._DEFAULT_OTEL_PROPAGATORS + environ_propagators
+        environ[OTEL_PROPAGATORS] = ",".join(environ_propagators)
+
+        # Init and set CompositePropagator globally, like OTel API
+        propagators = []
+        for propagator in environ_propagators:
+            try:
+                propagators.append(
+                    next(
+                        iter_entry_points("opentelemetry_propagator", propagator)
+                    ).load()()
+                )
+            except Exception:
+                logger.exception(
+                    "Failed to load configured propagator `%s`", propagator
+                )
+                raise
+        set_global_textmap(CompositePropagator(propagators))
+
         # Set global HTTP response propagator
         set_global_response_propagator(SolarWindsTraceResponsePropagator())