From cd9c3e1594e0d14825e112a5a474ba30dce08746 Mon Sep 17 00:00:00 2001
From: Pierre Tessier <pierre@pierretessier.com>
Date: Wed, 22 Jun 2022 23:55:11 -0400
Subject: [PATCH] [payment] - add manual instrumentation (#157)

* add manual instrumentation

* use service name for tracer
---
 src/paymentservice/charge.js | 13 +++++++++++++
 src/paymentservice/server.js | 13 +++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/paymentservice/charge.js b/src/paymentservice/charge.js
index 2e1fa40c50..bf5ef5bd7c 100644
--- a/src/paymentservice/charge.js
+++ b/src/paymentservice/charge.js
@@ -15,6 +15,8 @@
 const cardValidator = require('simple-card-validator');
 const { v4: uuidv4 } = require('uuid');
 const pino = require('pino');
+const opentelemetry = require('@opentelemetry/api');
+const tracer = opentelemetry.trace.getTracer("paymentservice");
 
 const logger = pino({
   name: 'paymentservice-charge',
@@ -56,6 +58,9 @@ class ExpiredCreditCard extends CreditCardError {
  * @return transaction_id - a random uuid v4.
  */
 module.exports = function charge (request) {
+  // create and start span
+  const span = tracer.startSpan("charge")
+
   const { amount, credit_card: creditCard } = request;
   const cardNumber = creditCard.credit_card_number;
   const cardInfo = cardValidator(cardNumber);
@@ -63,6 +68,10 @@ module.exports = function charge (request) {
     card_type: cardType,
     valid
   } = cardInfo.getCardDetails();
+  span.setAttributes({
+    "app.payment.charge.cardType": cardType,
+    "app.payment.charge.valid": valid
+  })
 
   if (!valid) { throw new InvalidCreditCard(); }
 
@@ -79,5 +88,9 @@ module.exports = function charge (request) {
   logger.info(`Transaction processed: ${cardType} ending ${cardNumber.substr(-4)} \
     Amount: ${amount.currency_code}${amount.units}.${amount.nanos}`);
 
+  span.setAttribute("app.payment.charged", true);
+  // a manually created span needs to be ended
+  span.end();
+
   return { transaction_id: uuidv4() };
 };
diff --git a/src/paymentservice/server.js b/src/paymentservice/server.js
index 7e695e2d04..406022c874 100644
--- a/src/paymentservice/server.js
+++ b/src/paymentservice/server.js
@@ -16,6 +16,7 @@ const path = require('path');
 const grpc = require('@grpc/grpc-js');
 const pino = require('pino');
 const protoLoader = require('@grpc/proto-loader');
+const opentelemetry = require('@opentelemetry/api');
 
 const charge = require('./charge');
 
@@ -45,11 +46,23 @@ class HipsterShopServer {
    * @param {*} callback  fn(err, ChargeResponse)
    */
   static ChargeServiceHandler(call, callback) {
+    // get the current auto-instrumented span in context
+    const span = opentelemetry.trace.getSpan(opentelemetry.context.active())
     try {
+      const amount = call.request.amount;
+      span.setAttributes({
+        "app.payment.currency": amount.currency_code,
+        "app.payment.cost": parseFloat(amount.units + "." + amount.nanos)
+      });
       logger.info(`PaymentService#Charge invoked with request ${JSON.stringify(call.request)}`);
+
       const response = charge(call.request);
       callback(null, response);
+
     } catch (err) {
+      // record exception in span (will create a span event)
+      span.recordException(err);
+      span.setStatus({code: opentelemetry.SpanStatusCode.ERROR})
       console.warn(err);
       callback(err);
     }