feat: add 'metric' logger method to accept otel metrics (#65)

* feat: add 'metric' logger method to accept otel metrics

* feat: server support to recognize `metrics` from the frontend

server/server.js

@@ -10,6 +10,11 @@ type ExpressResponse = express$Response; // eslint-disable-line no-undef
 
 type Payload = { [string]: string };
 
+export type Metric = {|
+  name: string,
+  dimensions: Payload,
+|};
+
 type Logger = {|
   log: (
     req: ExpressRequest,
@@ -19,6 +24,7 @@ type Logger = {|
     meta?: Payload
   ) => void,
   track: (req: ExpressRequest, payload: Payload, meta?: Payload) => void,
+  metric: (req: ExpressRequest, payload: Metric, meta?: Payload) => void,
   meta: (req: ExpressRequest, meta: Payload) => void,
 |};
 
@@ -66,6 +72,18 @@ export const defaultLogger: Logger = {
     );
   },
 
+  metric(req, metric) {
+    console.log(
+      `[metric].${metric.name}\n`,
+      Object.keys(metric.dimensions)
+        .map((key) => {
+          return `\t${key}: ${metric.dimensions[key]}`;
+        })
+        .join("\n"),
+      "\n"
+    );
+  },
+
   meta(req, meta) {
     console.log(
       "[meta]\n",
@@ -85,11 +103,13 @@ export function log(
   logs: {|
     events: $ReadOnlyArray<Event>,
     tracking?: $ReadOnlyArray<Tracking>,
+    metrics?: $ReadOnlyArray<Metric>,
     meta?: Meta,
   |}
 ) {
   const events = logs.events || [];
   const tracking = logs.tracking || [];
+  const metrics = logs.metrics || [];
   const meta = logs.meta || {};
 
   if (logger.meta) {
@@ -115,6 +135,12 @@ export function log(
       logger.track(req, track, meta);
     });
   }
+
+  if (logger.metric) {
+    metrics.forEach((metric) => {
+      logger.metric(req, metric);
+    });
+  }
 }
 
 type Query = {
@@ -126,6 +152,7 @@ type Query = {
 type Body = {|
   events: $ReadOnlyArray<Event>,
   tracking?: $ReadOnlyArray<Tracking>,
+  metrics?: $ReadOnlyArray<Metric>,
   meta: Meta,
 |};
 
@@ -140,8 +167,8 @@ export function handleRequest(req: ExpressRequest, logger: Logger) {
   const body: Body = req.body || {};
 
   if (method.toLowerCase() === "post") {
-    const { events, tracking, meta } = body;
-    log(req, logger, { events, tracking, meta });
+    const { events, tracking, metrics, meta } = body;
+    log(req, logger, { events, tracking, metrics, meta });
   } else {
     const { event, level = LOG_LEVEL.INFO, ...payload } = query;
 

src/logger.js

@@ -19,7 +19,7 @@ import {
 import { LOG_LEVEL, PROTOCOL } from "./constants";
 import { extendIfDefined } from "./util";
 import { type Transport, getHTTPTransport } from "./http";
-import type { Payload } from "./types";
+import type { Metric, Payload } from "./types";
 
 type LoggerOptions = {|
   url?: string,
@@ -34,6 +34,7 @@ type LoggerOptions = {|
 type ClientPayload = Payload;
 type Log = (name: string, payload?: ClientPayload) => LoggerType; // eslint-disable-line no-use-before-define
 type Track = (payload: ClientPayload) => LoggerType; // eslint-disable-line no-use-before-define
+type LogMetric = (payload: Metric) => LoggerType; // eslint-disable-line no-use-before-define
 
 type Builder = (Payload) => ClientPayload;
 type AddBuilder = (Builder) => LoggerType; // eslint-disable-line no-use-before-define
@@ -45,6 +46,7 @@ export type LoggerType = {|
   error: Log,
 
   track: Track,
+  metric: LogMetric,
 
   flush: () => ZalgoPromise<void>,
   immediateFlush: () => ZalgoPromise<void>,
@@ -73,6 +75,7 @@ export function Logger({
     payload: Payload,
   |}> = [];
   let tracking: Array<Payload> = [];
+  let metrics: Array<Metric> = [];
 
   const payloadBuilders: Array<Builder> = [];
   const metaBuilders: Array<Builder> = [];
@@ -119,7 +122,7 @@ export function Logger({
         return;
       }
 
-      if (!events.length && !tracking.length) {
+      if (!events.length && !tracking.length && !metrics.length) {
         return;
       }
 
@@ -144,6 +147,7 @@ export function Logger({
             events,
             meta,
             tracking,
+            metrics,
           },
           enableSendBeacon,
         }).catch(noop);
@@ -171,6 +175,7 @@ export function Logger({
 
       events = [];
       tracking = [];
+      metrics = [];
 
       return ZalgoPromise.resolve(res).then(noop);
     });
@@ -276,6 +281,22 @@ export function Logger({
     return logger; // eslint-disable-line no-use-before-define
   }
 
+  function metric(metricPayload: Metric): LoggerType {
+    if (!isBrowser()) {
+      return logger; // eslint-disable-line no-use-before-define
+    }
+
+    print(
+      LOG_LEVEL.DEBUG,
+      `metric.${metricPayload.name}`,
+      metricPayload.dimensions
+    );
+
+    metrics.push(metricPayload);
+
+    return logger; // eslint-disable-line no-use-before-define
+  }
+
   function setTransport(newTransport: Transport): LoggerType {
     transport = newTransport;
     return logger; // eslint-disable-line no-use-before-define
@@ -337,6 +358,7 @@ export function Logger({
     warn,
     error,
     track,
+    metric,
     flush,
     immediateFlush,
     addPayloadBuilder,

src/types.js

@@ -1,3 +1,8 @@
 /* @flow */
 
 export type Payload = { [string]: string | boolean | null | void };
+
+export type Metric = {|
+  name: string,
+  dimensions: Payload,
+|};