Add a configuration manager (#466)

Fixes #123

This basically removes loader.py (uses entry points instead) and all the calls
for set_preferred_implementation* in order to cleanly separate user code from
configuration. It introduces a configuration manager that can have
configuration set by a configuration file or environment variables that
override the former configuration method.

Co-authored-by: Mauricio Vásquez <mauricio@kinvolk.io>
Co-authored-by: Chris Kleinknecht <libc@google.com>

docs/api/api.rst

@@ -9,4 +9,3 @@ OpenTelemetry Python API
     context
     metrics
     trace
-    util.loader

docs/examples/basic_tracer/tracer.py

@@ -45,19 +45,16 @@
     print("Using ConsoleSpanExporter")
     exporter = ConsoleSpanExporter()
 
-# The preferred tracer implementation must be set, as the opentelemetry-api
-# defines the interface with a no-op implementation.
-trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
-
+trace.set_tracer_provider(TracerProvider())
 # We tell OpenTelemetry who it is that is creating spans. In this case, we have
 # no real name (no setup.py), so we make one up. If we had a version, we would
 # also specify it here.
 tracer = trace.get_tracer(__name__)
 
 # SpanExporter receives the spans and send them to the target location.
 span_processor = BatchExportSpanProcessor(exporter)
+trace.get_tracer_provider().add_span_processor(span_processor)
 
-trace.tracer_provider().add_span_processor(span_processor)
 with tracer.start_as_current_span("foo"):
     with tracer.start_as_current_span("bar"):
         with tracer.start_as_current_span("baz"):

docs/examples/http/server.py

@@ -39,19 +39,17 @@
 else:
     exporter = ConsoleSpanExporter()
 
-# The preferred tracer implementation must be set, as the opentelemetry-api
-# defines the interface with a no-op implementation.
-trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
 tracer = trace.get_tracer(__name__)
 
 # SpanExporter receives the spans and send them to the target location.
 span_processor = BatchExportSpanProcessor(exporter)
-trace.tracer_provider().add_span_processor(span_processor)
+trace.set_tracer_provider(TracerProvider())
+trace.get_tracer_provider().add_span_processor(span_processor)
 
 # Integrations are the glue that binds the OpenTelemetry API and the
 # frameworks and libraries that are used together, automatically creating
 # Spans and propagating context as appropriate.
-http_requests.enable(trace.tracer_provider())
+http_requests.enable(trace.get_tracer_provider())
 app = flask.Flask(__name__)
 app.wsgi_app = OpenTelemetryMiddleware(app.wsgi_app)
 

docs/examples/http/tracer_client.py

@@ -37,10 +37,8 @@
 else:
     exporter = ConsoleSpanExporter()
 
-# The preferred tracer implementation must be set, as the opentelemetry-api
-# defines the interface with a no-op implementation.
-trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
-tracer_provider = trace.tracer_provider()
+trace.set_tracer_provider(TracerProvider())
+tracer_provider = trace.get_tracer_provider()
 
 # SpanExporter receives the spans and send them to the target location.
 span_processor = BatchExportSpanProcessor(exporter)

docs/examples/metrics/observer_example.py

@@ -19,15 +19,14 @@
 import psutil
 
 from opentelemetry import metrics
-from opentelemetry.sdk.metrics import LabelSet, MeterProvider
+from opentelemetry.sdk.metrics import LabelSet
 from opentelemetry.sdk.metrics.export import ConsoleMetricsExporter
 from opentelemetry.sdk.metrics.export.batcher import UngroupedBatcher
 from opentelemetry.sdk.metrics.export.controller import PushController
 
 # Configure a stateful batcher
 batcher = UngroupedBatcher(stateful=True)
 
-metrics.set_preferred_meter_provider_implementation(lambda _: MeterProvider())
 meter = metrics.get_meter(__name__)
 
 # Exporter to export metrics to the console

docs/examples/metrics/prometheus.py

@@ -21,14 +21,13 @@
 
 from opentelemetry import metrics
 from opentelemetry.ext.prometheus import PrometheusMetricsExporter
-from opentelemetry.sdk.metrics import Counter, MeterProvider
+from opentelemetry.sdk.metrics import Counter
 from opentelemetry.sdk.metrics.export.controller import PushController
 
 # Start Prometheus client
 start_http_server(port=8000, addr="localhost")
 
 # Meter is responsible for creating and recording metrics
-metrics.set_preferred_meter_provider_implementation(lambda _: MeterProvider())
 meter = metrics.get_meter(__name__)
 # exporter to export metrics to Prometheus
 prefix = "MyAppPrefix"

docs/examples/metrics/record.py

@@ -19,13 +19,10 @@
 import time
 
 from opentelemetry import metrics
-from opentelemetry.sdk.metrics import Counter, MeterProvider
+from opentelemetry.sdk.metrics import Counter
 from opentelemetry.sdk.metrics.export import ConsoleMetricsExporter
 from opentelemetry.sdk.metrics.export.controller import PushController
 
-# The preferred tracer implementation must be set, as the opentelemetry-api
-# defines the interface with a no-op implementation.
-metrics.set_preferred_meter_provider_implementation(lambda _: MeterProvider())
 # Meter is responsible for creating and recording metrics
 meter = metrics.get_meter(__name__)
 # exporter to export metrics to the console

docs/examples/metrics/simple_example.py

@@ -23,7 +23,7 @@
 import time
 
 from opentelemetry import metrics
-from opentelemetry.sdk.metrics import Counter, Measure, MeterProvider
+from opentelemetry.sdk.metrics import Counter, Measure
 from opentelemetry.sdk.metrics.export import ConsoleMetricsExporter
 from opentelemetry.sdk.metrics.export.controller import PushController
 
@@ -44,7 +44,6 @@ def usage(argv):
         sys.exit(1)
 
 # Meter is responsible for creating and recording metrics
-metrics.set_preferred_meter_provider_implementation(lambda _: MeterProvider())
 
 # Meter's namespace corresponds to the string passed as the first argument Pass
 # in True/False to indicate whether the batcher is stateful. True indicates the

docs/examples/opentelemetry-example-app/src/opentelemetry_example_app/flask_example.py

@@ -23,7 +23,6 @@
 import opentelemetry.ext.http_requests
 from opentelemetry import trace
 from opentelemetry.ext.flask import instrument_app
-from opentelemetry.sdk.trace import TracerProvider
 
 
 def configure_opentelemetry(flask_app: flask.Flask):
@@ -42,20 +41,14 @@ def configure_opentelemetry(flask_app: flask.Flask):
     """
     # Start by configuring all objects required to ensure
     # a complete end to end workflow.
-    # The preferred implementation of these objects must be set,
-    # as the opentelemetry-api defines the interface with a no-op
-    # implementation.
-    trace.set_preferred_tracer_provider_implementation(
-        lambda _: TracerProvider()
-    )
 
     # Next, we need to configure how the values that are used by
     # traces and metrics are propagated (such as what specific headers
     # carry this value).
     # Integrations are the glue that binds the OpenTelemetry API
     # and the frameworks and libraries that are used together, automatically
     # creating Spans and propagating context as appropriate.
-    opentelemetry.ext.http_requests.enable(trace.tracer_provider())
+    opentelemetry.ext.http_requests.enable(trace.get_tracer_provider())
     instrument_app(flask_app)
 
 

docs/examples/opentracing/main.py

@@ -3,13 +3,10 @@
 from opentelemetry import trace
 from opentelemetry.ext import opentracing_shim
 from opentelemetry.ext.jaeger import JaegerSpanExporter
-from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import SimpleExportSpanProcessor
 from rediscache import RedisCache
 
-# Configure the tracer using the default implementation
-trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
-tracer_provider = trace.tracer_provider()
+tracer_provider = trace.get_tracer_provider()
 
 # Configure the tracer to export traces to Jaeger
 jaeger_exporter = JaegerSpanExporter(

examples/metrics/collector.py

@@ -21,11 +21,10 @@
 from opentelemetry.ext.otcollector.metrics_exporter import (
     CollectorMetricsExporter,
 )
-from opentelemetry.sdk.metrics import Counter, MeterProvider
+from opentelemetry.sdk.metrics import Counter
 from opentelemetry.sdk.metrics.export.controller import PushController
 
 # Meter is responsible for creating and recording metrics
-metrics.set_preferred_meter_provider_implementation(lambda _: MeterProvider())
 meter = metrics.get_meter(__name__)
 # exporter to export metrics to OT Collector
 exporter = CollectorMetricsExporter(

ext/opentelemetry-ext-dbapi/README.rst

@@ -15,7 +15,6 @@ Usage
     from opentelemetry.trace import tracer_provider
     from opentelemetry.ext.dbapi import trace_integration
 
-    trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
     tracer = trace.get_tracer(__name__)
     # Ex: mysql.connector
     trace_integration(tracer_provider(), mysql.connector, "connect", "mysql", "sql")

ext/opentelemetry-ext-jaeger/README.rst

@@ -32,10 +32,8 @@ gRPC is still not supported by this implementation.
 
     from opentelemetry import trace
     from opentelemetry.ext import jaeger
-    from opentelemetry.sdk.trace import TracerProvider
     from opentelemetry.sdk.trace.export import BatchExportSpanProcessor
 
-    trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
     tracer = trace.get_tracer(__name__)
 
     # create a JaegerSpanExporter

ext/opentelemetry-ext-jaeger/examples/jaeger_exporter_example.py

@@ -2,10 +2,8 @@
 
 from opentelemetry import trace
 from opentelemetry.ext import jaeger
-from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import BatchExportSpanProcessor
 
-trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
 tracer = trace.get_tracer(__name__)
 
 # create a JaegerSpanExporter
@@ -26,7 +24,7 @@
 span_processor = BatchExportSpanProcessor(jaeger_exporter)
 
 # add to the tracer factory
-trace.tracer_provider().add_span_processor(span_processor)
+trace.get_tracer_provider().add_span_processor(span_processor)
 
 # create some spans for testing
 with tracer.start_as_current_span("foo") as foo:

ext/opentelemetry-ext-opentracing-shim/src/opentelemetry/ext/opentracing_shim/__init__.py

@@ -29,12 +29,8 @@
     import time
 
     from opentelemetry import trace
-    from opentelemetry.sdk.trace import TracerProvider
     from opentelemetry.ext.opentracing_shim import create_tracer
 
-    # Tell OpenTelemetry which Tracer implementation to use.
-    trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
-
     # Create an OpenTelemetry Tracer.
     otel_tracer = trace.get_tracer(__name__)
 

ext/opentelemetry-ext-opentracing-shim/tests/test_shim.py

@@ -43,19 +43,11 @@ class TestShim(TestCase):
 
     def setUp(self):
         """Create an OpenTelemetry tracer and a shim before every test case."""
-
-        self.shim = opentracingshim.create_tracer(trace.tracer_provider())
+        trace.set_tracer_provider(TracerProvider())
+        self.shim = opentracingshim.create_tracer(trace.get_tracer_provider())
 
     @classmethod
     def setUpClass(cls):
-        """Set preferred tracer implementation only once rather than before
-        every test method.
-        """
-
-        trace.set_preferred_tracer_provider_implementation(
-            lambda T: TracerProvider()
-        )
-
         # Save current propagator to be restored on teardown.
         cls._previous_propagator = propagators.get_global_httptextformat()
 

ext/opentelemetry-ext-otcollector/tests/test_otcollector_metrics_exporter.py

@@ -34,25 +34,11 @@ class TestCollectorMetricsExporter(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
         # pylint: disable=protected-access
-        cls._meter_defaults = (
-            metrics._METER_PROVIDER,
-            metrics._METER_PROVIDER_FACTORY,
-        )
-        metrics.set_preferred_meter_provider_implementation(
-            lambda _: MeterProvider()
-        )
+        metrics.set_meter_provider(MeterProvider())
         cls._meter = metrics.get_meter(__name__)
         kvp = {"environment": "staging"}
         cls._test_label_set = cls._meter.get_label_set(kvp)
 
-    @classmethod
-    def tearDownClass(cls):
-        # pylint: disable=protected-access
-        (
-            metrics._METER_PROVIDER,
-            metrics._METER_PROVIDER_FACTORY,
-        ) = cls._meter_defaults
-
     def test_constructor(self):
         mock_get_node = mock.Mock()
         patch = mock.patch(

ext/opentelemetry-ext-prometheus/README.rst

@@ -29,15 +29,14 @@ The **OpenTelemetry Prometheus Exporter** allows to export `OpenTelemetry`_ metr
 
     from opentelemetry import metrics
     from opentelemetry.ext.prometheus import PrometheusMetricsExporter
-    from opentelemetry.sdk.metrics import Counter, Meter
+    from opentelemetry.sdk.metrics import Counter
     from opentelemetry.sdk.metrics.export.controller import PushController
     from prometheus_client import start_http_server
 
     # Start Prometheus client
     start_http_server(port=8000, addr="localhost")
 
     # Meter is responsible for creating and recording metrics
-    metrics.set_preferred_meter_implementation(lambda _: Meter())
     meter = metrics.meter()
     # exporter to export metrics to Prometheus
     prefix = "MyAppPrefix"

ext/opentelemetry-ext-prometheus/tests/test_prometheus_exporter.py

@@ -21,14 +21,16 @@
     CustomCollector,
     PrometheusMetricsExporter,
 )
+from opentelemetry.metrics import get_meter_provider, set_meter_provider
 from opentelemetry.sdk import metrics
 from opentelemetry.sdk.metrics.export import MetricRecord, MetricsExportResult
 from opentelemetry.sdk.metrics.export.aggregate import CounterAggregator
 
 
 class TestPrometheusMetricExporter(unittest.TestCase):
     def setUp(self):
-        self._meter = metrics.MeterProvider().get_meter(__name__)
+        set_meter_provider(metrics.MeterProvider())
+        self._meter = get_meter_provider().get_meter(__name__)
         self._test_metric = self._meter.create_metric(
             "testname",
             "testdesc",
@@ -74,7 +76,7 @@ def test_export(self):
             self.assertIs(result, MetricsExportResult.SUCCESS)
 
     def test_counter_to_prometheus(self):
-        meter = metrics.MeterProvider().get_meter(__name__)
+        meter = get_meter_provider().get_meter(__name__)
         metric = meter.create_metric(
             "test@name",
             "testdesc",
@@ -110,8 +112,7 @@ def test_counter_to_prometheus(self):
     # TODO: Add unit test once Measure Aggregators are available
 
     def test_invalid_metric(self):
-
-        meter = metrics.MeterProvider().get_meter(__name__)
+        meter = get_meter_provider().get_meter(__name__)
         metric = meter.create_metric(
             "tesname", "testdesc", "unit", int, TestMetric
         )

ext/opentelemetry-ext-psycopg2/README.rst

@@ -13,10 +13,8 @@ Usage
 
     import psycopg2
     from opentelemetry import trace
-    from opentelemetry.sdk.trace import TracerProvider
     from opentelemetry.trace.ext.psycopg2 import trace_integration
 
-    trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
     tracer = trace.get_tracer(__name__)
     trace_integration(tracer)
     cnx = psycopg2.connect(database='Database')

ext/opentelemetry-ext-testutil/src/opentelemetry/ext/testutil/wsgitestutil.py

@@ -16,10 +16,8 @@ class WsgiTestBase(unittest.TestCase):
     @classmethod
     def setUpClass(cls):
         global _MEMORY_EXPORTER  # pylint:disable=global-statement
-        trace_api.set_preferred_tracer_provider_implementation(
-            lambda T: TracerProvider()
-        )
-        tracer_provider = trace_api.tracer_provider()
+        trace_api.set_tracer_provider(TracerProvider())
+        tracer_provider = trace_api.get_tracer_provider()
         _MEMORY_EXPORTER = InMemorySpanExporter()
         span_processor = export.SimpleExportSpanProcessor(_MEMORY_EXPORTER)
         tracer_provider.add_span_processor(span_processor)

ext/opentelemetry-ext-zipkin/README.rst

@@ -30,10 +30,8 @@ This exporter always send traces to the configured Zipkin collector using HTTP.
 
     from opentelemetry import trace
     from opentelemetry.ext import zipkin
-    from opentelemetry.sdk.trace import TracerProvider
     from opentelemetry.sdk.trace.export import BatchExportSpanProcessor
 
-    trace.set_preferred_tracer_provider_implementation(lambda T: TracerProvider())
     tracer = trace.get_tracer(__name__)
 
     # create a ZipkinSpanExporter