Adds metric prototype

Fixes open-telemetry#1835

CHANGELOG.md

@@ -88,6 +88,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#1877](https://github.com/open-telemetry/opentelemetry-python/pull/1877))
 - Added support for CreateKey functionality.
   ([#1853](https://github.com/open-telemetry/opentelemetry-python/pull/1853))
+- Add metrics
+  ([#1887](https://github.com/open-telemetry/opentelemetry-python/pull/1887))
 
 ### Changed
 - Updated get_tracer to return an empty string when passed an invalid name

docs/api/api.rst

@@ -9,4 +9,5 @@ OpenTelemetry Python API
     baggage
     context
     trace
+    metrics
     environment_variables

docs/examples/metrics/grocery/README.rst

@@ -0,0 +1,10 @@
+Grocery
+=======
+
+This is the implementation of the grocery scenario.
+
+
+Useful links
+------------
+
+.. _Grocery: https://github.com/open-telemetry/oteps/blob/main/text/metrics/0146-metrics-prototype-scenarios.md#scenario-1-grocery

docs/examples/metrics/grocery/grocery.py

@@ -0,0 +1,94 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from opentelemetry.metrics import get_meter_provider
+from opentelemetry.sdk.metrics.export import ConsoleExporter
+
+exporter = ConsoleExporter()
+
+get_meter_provider().start_pipeline_equivalent(exporter, 5)
+
+meter = get_meter_provider().get_meter()
+
+
+order_counter = meter.create_counter(
+    name="orders",
+    description="number of orders",
+    unit="order",
+    value_type=int,
+)
+
+amount_counter = meter.create_counter(
+    name="amount",
+    description="amount paid",
+    unit="dollar",
+    value_type=int,
+)
+
+sold_items_counter = meter.create_counter(
+    name="sold items",
+    description="number of sold items",
+    unit="item",
+    value_type=int,
+)
+
+customers_in_store = meter.create_up_down_counter(
+    name="customers in store",
+    description="amount of customers present in store",
+    unit="customer",
+    value_type=int,
+)
+
+
+class GroceryStore:
+    def __init__(self, name):
+        self._name = name
+
+    def process_order(self, customer_name, potatoes=0, tomatoes=0):
+        order_counter.add(1, {"store": self._name, "customer": customer_name})
+
+        amount_counter.add(
+            (potatoes * 1) + (tomatoes * 3),
+            {"store": self._name, "customer": customer_name},
+        )
+
+        sold_items_counter.add(
+            potatoes,
+            {
+                "store": self._name,
+                "customer": customer_name,
+                "item": "potato",
+            },
+        )
+
+        sold_items_counter.add(
+            tomatoes,
+            {
+                "store": self._name,
+                "customer": customer_name,
+                "item": "tomato",
+            },
+        )
+
+    def enter_customer(self, customer_name, account_type):
+
+        customers_in_store.add(
+            1, {"store": self._name, "account_type": account_type}
+        )
+
+    def exit_customer(self, customer_name, account_type):
+
+        customers_in_store.add(
+            -1, {"store": self._name, "account_type": account_type}
+        )

docs/getting_started/otlpcollector_example.py

@@ -14,10 +14,13 @@
 
 # otcollector.py
 
-from opentelemetry import trace
+from opentelemetry import metrics, trace
+from opentelemetry.exporter.otlp.metrics_exporter import OTLPMetricsExporter
 from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import (
     OTLPSpanExporter,
 )
+from opentelemetry.sdk.metrics import MeterProvider
+from opentelemetry.sdk.metrics.export import PushController
 from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import BatchSpanProcessor
 

docs/sdk/sdk.rst

@@ -8,5 +8,6 @@ OpenTelemetry Python SDK
 
     resources
     trace
+    metrics
     error_handler
     environment_variables

exporter/opentelemetry-exporter-otlp-proto-grpc/src/opentelemetry/exporter/otlp/proto/grpc/exporter.py

@@ -125,7 +125,7 @@ def _translate_key_values(key: Text, value: Any) -> KeyValue:
     return KeyValue(key=key, value=_translate_value(value))
 
 
-def get_resource_data(
+def _get_resource_data(
     sdk_resource_instrumentation_library_data: Dict[
         SDKResource, ResourceDataT
     ],

opentelemetry-api/src/opentelemetry/environment_variables/__init__.py

@@ -41,3 +41,14 @@
 """
 .. envvar:: OTEL_PYTHON_TRACER_PROVIDER
 """
+
+OTEL_PYTHON_METER_PROVIDER = "OTEL_PYTHON_METER_PROVIDER"
+"""
+.. envvar:: OTEL_PYTHON_METER_PROVIDER
+"""
+
+OTEL_METRICS_EXPORTER = "OTEL_METRICS_EXPORTER"
+"""
+.. envvar:: OTEL_METRICS_EXPORTER
+
+"""

opentelemetry-api/src/opentelemetry/metrics/instrument.py

@@ -0,0 +1,140 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# pylint: disable=abstract-class-instantiated
+# pylint: disable=too-many-ancestors
+# pylint: disable=useless-super-delegation
+
+
+from abc import ABC, abstractmethod
+from logging import getLogger
+from re import ASCII
+from re import compile as compile_
+from typing import Callable
+
+_logger = getLogger(__name__)
+
+
+class Instrument(ABC):
+
+    _name_regex = compile_(r"[a-zA-Z][-.\w]{0,62}", ASCII)
+
+    @abstractmethod
+    def __init__(self, name, unit="", description=""):
+
+        if self._name_regex.fullmatch(name) is None:
+            raise Exception("Invalid instrument name {}".format(name))
+
+        if len(unit) > 63 or any(ord(character) > 127 for character in unit):
+            raise Exception("unit must be 63 characters or shorter")
+
+
+class Synchronous(Instrument):
+    pass
+
+
+class Asynchronous(Instrument):
+    @abstractmethod
+    def __init__(self, name, callback, unit="", description=""):
+
+        if not isinstance(callback, Callable):
+            raise Exception("callback must be callable")
+
+        super().__init__(name, unit=unit, description=description)
+
+
+class Adding(Instrument):
+    pass
+
+
+class Grouping(Instrument):
+    pass
+
+
+class Monotonic(Adding):
+    pass
+
+
+class NonMonotonic(Adding):
+    pass
+
+
+class Counter(Monotonic, Synchronous):
+    @abstractmethod
+    def add(self, amount, **attributes):
+        if amount < 0:
+            raise Exception("Amount must be non-negative")
+
+
+class DefaultCounter(Counter):
+    def __init__(self, name, unit="", description=""):
+        super().__init__(name, unit=unit, description=description)
+
+    def add(self, amount, **attributes):
+        return super().add(amount, **attributes)
+
+
+class UpDownCounter(NonMonotonic, Synchronous):
+    @abstractmethod
+    def add(self, amount, **attributes):
+        pass
+
+
+class DefaultUpDownCounter(UpDownCounter):
+    def __init__(self, name, unit="", description=""):
+        super().__init__(name, unit=unit, description=description)
+
+    def add(self, amount, **attributes):
+        return super().add(amount, **attributes)
+
+
+class ObservableCounter(Monotonic, Asynchronous):
+    pass
+
+
+class DefaultObservableCounter(ObservableCounter):
+    def __init__(self, name, callback, unit="", description=""):
+        super().__init__(name, callback, unit=unit, description=description)
+
+
+class ObservableUpDownCounter(NonMonotonic, Asynchronous):
+    pass
+
+
+class DefaultObservableUpDownCounter(ObservableUpDownCounter):
+    def __init__(self, name, callback, unit="", description=""):
+        super().__init__(name, callback, unit=unit, description=description)
+
+
+class Histogram(Grouping, Synchronous):
+    @abstractmethod
+    def record(self, amount, **attributes):
+        pass
+
+
+class DefaultHistogram(Histogram):
+    def __init__(self, name, unit="", description=""):
+        super().__init__(name, unit=unit, description=description)
+
+    def record(self, amount, **attributes):
+        return super().record(amount, **attributes)
+
+
+class ObservableGauge(Grouping, Asynchronous):
+    pass
+
+
+class DefaultObservableGauge(ObservableGauge):
+    def __init__(self, name, callback, unit="", description=""):
+        super().__init__(name, callback, unit=unit, description=description)