chore!: split metrics into its own api package (open-telemetry#1797)

Author: dyladan

api/README.md

@@ -10,7 +10,7 @@ This package provides everything needed to interact with the OpenTelemetry API,
 
 ## Quick Start
 
-To get started you need to install the SDK and plugins, create a TracerProvider and/or MeterProvider, and register it with the API.
+To get started you need to install the SDK and plugins, create a TracerProvider, and register it with the API.
 
 ### Install Dependencies
 
@@ -23,11 +23,6 @@ $ npm install \
     @opentelemetry/tracing \
     @opentelemetry/exporter-jaeger \ # add exporters as needed
     @opentelemetry/plugin-http # add plugins as needed
-
-$ # Install metrics dependencies
-$ npm install \
-    @opentelemetry/metrics \
-    @opentelemetry/exporter-prometheus # add exporters as needed
 ```
 
 > Note: this example is for node.js. See [examples/tracer-web](https://github.com/open-telemetry/opentelemetry-js/tree/master/examples/tracer-web) for a browser example.
@@ -74,27 +69,6 @@ tracerProvider.addSpanProcessor(
 tracerProvider.register();
 ```
 
-#### Metrics
-
-```javascript
-const api = require("@opentelemetry/api");
-const { MeterProvider } = require("@opentelemetry/metrics");
-const { PrometheusExporter } = require("@opentelemetry/exporter-prometheus");
-
-const meterProvider = new MeterProvider({
-  // The Prometheus exporter runs an HTTP server which
-  // the Prometheus backend scrapes to collect metrics.
-  exporter: new PrometheusExporter({ startServer: true }),
-  interval: 1000,
-});
-
-/**
- * Registering the provider with the API allows it to be discovered
- * and used by instrumentation libraries.
- */
-api.metrics.setGlobalMeterProvider(meterProvider);
-```
-
 ## Version Compatibility
 
 Because the npm installer and node module resolution algorithm could potentially allow two or more copies of any given package to exist within the same `node_modules` structure, the OpenTelemetry API takes advantage of a variable on the `global` object to store the global API. When an API method in the API package is called, it checks if this `global` API exists and proxies calls to it if and only if it is a compatible API version. This means if a package has a dependency on an OpenTelemetry API version which is not compatible with the API used by the end user, the package will receive a no-op implementation of the API.
@@ -122,7 +96,6 @@ tracerProvider.register({
 If you are writing an instrumentation library, or prefer to call the API methods directly rather than using the `register` method on the Tracer/Meter Provider, OpenTelemetry provides direct access to the underlying API methods through the `@opentelemetry/api` package. API entry points are defined as global singleton objects `trace`, `metrics`, `propagation`, and `context` which contain methods used to initialize SDK implementations and acquire resources from the API.
 
 - [Trace API Documentation][trace-api-docs]
-- [Metrics API Documentation][metrics-api-docs]
 - [Propagation API Documentation][propagation-api-docs]
 - [Context API Documentation][context-api-docs]
 
@@ -136,13 +109,6 @@ api.trace.getTracerProvider();
 /* returns a tracer from the registered global tracer provider (no-op if a working provider has not been initialized) */
 api.trace.getTracer(name, version);
 
-/* Initialize MeterProvider */
-api.metrics.setGlobalMeterProvider(meterProvider);
-/* returns meterProvider (no-op if a working provider has not been initialized) */
-api.metrics.getMeterProvider();
-/* returns a meter from the registered global meter provider (no-op if a working provider has not been initialized) */
-api.metrics.getMeter(name, version);
-
 /* Initialize Propagator */
 api.propagation.setGlobalPropagator(httpTraceContextPropagator);
 

api/package.json

@@ -30,7 +30,6 @@
     "browser",
     "tracing",
     "profiling",
-    "metrics",
     "stats",
     "monitoring"
   ],

api/src/api/global-utils.ts

@@ -16,16 +16,13 @@
 
 import { ContextManager } from '@opentelemetry/context-base';
 import { TextMapPropagator } from '../context/propagation/TextMapPropagator';
-import { MeterProvider } from '../metrics/MeterProvider';
 import { TracerProvider } from '../trace/tracer_provider';
 import { _globalThis } from '../platform';
 
 export const GLOBAL_CONTEXT_MANAGER_API_KEY = Symbol.for(
   'io.opentelemetry.js.api.context'
 );
-export const GLOBAL_METRICS_API_KEY = Symbol.for(
-  'io.opentelemetry.js.api.metrics'
-);
+
 export const GLOBAL_PROPAGATION_API_KEY = Symbol.for(
   'io.opentelemetry.js.api.propagation'
 );
@@ -34,7 +31,6 @@ export const GLOBAL_TRACE_API_KEY = Symbol.for('io.opentelemetry.js.api.trace');
 type Get<T> = (version: number) => T;
 type OtelGlobal = Partial<{
   [GLOBAL_CONTEXT_MANAGER_API_KEY]: Get<ContextManager>;
-  [GLOBAL_METRICS_API_KEY]: Get<MeterProvider>;
   [GLOBAL_PROPAGATION_API_KEY]: Get<TextMapPropagator>;
   [GLOBAL_TRACE_API_KEY]: Get<TracerProvider>;
 }>;

api/src/api/metrics.ts

@@ -22,15 +22,6 @@ export * from './context/propagation/TextMapPropagator';
 export * from './context/propagation/NoopTextMapPropagator';
 export * from './baggage/Baggage';
 export * from './baggage/EntryValue';
-export * from './metrics/BatchObserverResult';
-export * from './metrics/BoundInstrument';
-export * from './metrics/Meter';
-export * from './metrics/MeterProvider';
-export * from './metrics/Metric';
-export * from './metrics/NoopMeter';
-export * from './metrics/NoopMeterProvider';
-export * from './metrics/Observation';
-export * from './metrics/ObserverResult';
 export * from './trace/attributes';
 export * from './trace/Event';
 export * from './trace/link_context';
@@ -78,17 +69,12 @@ import { TraceAPI } from './api/trace';
 /** Entrypoint for trace API */
 export const trace = TraceAPI.getInstance();
 
-import { MetricsAPI } from './api/metrics';
-/** Entrypoint for metrics API */
-export const metrics = MetricsAPI.getInstance();
-
 import { PropagationAPI } from './api/propagation';
 /** Entrypoint for propagation API */
 export const propagation = PropagationAPI.getInstance();
 
 export default {
   trace,
-  metrics,
   context,
   propagation,
 };