Fix preferred_aggregation + preferred_temporality example (#2911)

Author: lzchen

CHANGELOG.md

@@ -15,6 +15,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#2870](https://github.com/open-telemetry/opentelemetry-python/pull/2870))
 - Fix: Remove `LogEmitter.flush()` to align with OTel Log spec
   ([#2863](https://github.com/open-telemetry/opentelemetry-python/pull/2863))
+- Fix metric reader examples + added `preferred_temporality` and `preferred_aggregation`
+  for `ConsoleMetricExporter`
+  ([#2911](https://github.com/open-telemetry/opentelemetry-python/pull/2911))
 - Add support for setting OTLP export protocol with env vars, as defined in the
   [specifications](https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/protocol/exporter.md#specify-protocol)
   ([#2893](https://github.com/open-telemetry/opentelemetry-python/pull/2893))

docs/examples/metrics/reader/preferred_aggregation.py

@@ -22,15 +22,17 @@
 )
 from opentelemetry.sdk.metrics.view import LastValueAggregation
 
-# Use console exporter for the example
-exporter = ConsoleMetricExporter()
-
 aggregation_last_value = {Counter: LastValueAggregation()}
 
-# Create a metric reader with custom preferred aggregation
+# Use console exporter for the example
+exporter = ConsoleMetricExporter(
+    preferred_aggregation=aggregation_last_value,
+)
+
+# The PeriodicExportingMetricReader takes the preferred aggregation
+# from the passed in exporter
 reader = PeriodicExportingMetricReader(
     exporter,
-    preferred_aggregation=aggregation_last_value,
     export_interval_millis=5_000,
 )
 

docs/examples/metrics/reader/preferred_temporality.py

@@ -22,25 +22,35 @@
     PeriodicExportingMetricReader,
 )
 
-# Use console exporter for the example
-exporter = ConsoleMetricExporter()
-
 temporality_cumulative = {Counter: AggregationTemporality.CUMULATIVE}
 temporality_delta = {Counter: AggregationTemporality.DELTA}
-# Create a metric reader with cumulative preferred temporality
-# The metrics that are exported using this reader will represent a cumulative value
+
+# Use console exporters for the example
+
+# The metrics that are exported using this exporter will represent a cumulative value
+exporter = ConsoleMetricExporter(
+    preferred_temporality=temporality_cumulative,
+)
+
+# The metrics that are exported using this exporter will represent a delta value
+exporter2 = ConsoleMetricExporter(
+    preferred_temporality=temporality_delta,
+)
+
+# The PeriodicExportingMetricReader takes the preferred aggregation
+# from the passed in exporter
 reader = PeriodicExportingMetricReader(
     exporter,
-    preferred_temporality=temporality_cumulative,
     export_interval_millis=5_000,
 )
-# Create a metric reader with delta preferred temporality
-# The metrics that are exported using this reader will represent a delta value
+
+# The PeriodicExportingMetricReader takes the preferred aggregation
+# from the passed in exporter
 reader2 = PeriodicExportingMetricReader(
-    exporter,
-    preferred_temporality=temporality_delta,
+    exporter2,
     export_interval_millis=5_000,
 )
+
 provider = MeterProvider(metric_readers=[reader, reader2])
 set_meter_provider(provider)
 
@@ -49,10 +59,10 @@
 counter = meter.create_counter("my-counter")
 
 # Two metrics are expected to be printed to the console per export interval.
-# The metric originating from the metric reader with a preferred temporality
+# The metric originating from the metric exporter with a preferred temporality
 # of cumulative will keep a running sum of all values added.
-# The metric originating from the metric reader with a preferred temporality
+# The metric originating from the metric exporter with a preferred temporality
 # of delta will have the sum value reset each export interval.
-for x in range(10):
-    counter.add(x)
-    time.sleep(2.0)
+counter.add(5)
+time.sleep(10)
+counter.add(20)

opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/export/__init__.py

@@ -136,8 +136,15 @@ def __init__(
             ["opentelemetry.sdk.metrics.export.MetricsData"], str
         ] = lambda metrics_data: metrics_data.to_json()
         + linesep,
+        preferred_temporality: Dict[type, AggregationTemporality] = None,
+        preferred_aggregation: Dict[
+            type, "opentelemetry.sdk.metrics.view.Aggregation"
+        ] = None,
     ):
-        super().__init__()
+        super().__init__(
+            preferred_temporality=preferred_temporality,
+            preferred_aggregation=preferred_aggregation,
+        )
         self.out = out
         self.formatter = formatter