Merge branch 'main' into manual_metrics_recommendationservice

docs/services/checkoutservice.md

@@ -109,7 +109,49 @@ Adding a span event with additional attributes:
 
 ## Metrics
 
-TBD
+### Initialize meter provider
+
+The OpenTelemetry SDK is initialized from `main` using the `initMeterProvider`
+function.
+
+```go
+func initMeterProvider() *sdkmetric.MeterProvider {
+    ctx := context.Background()
+
+    exporter, err := otlpmetricgrpc.New(ctx)
+    if err != nil {
+        log.Fatalf("new otlp metric grpc exporter failed: %v", err)
+    }
+
+    mp := sdkmetric.NewMeterProvider(sdkmetric.WithReader(sdkmetric.NewPeriodicReader(exporter)))
+    global.SetMeterProvider(mp)
+    return mp
+}
+```
+
+You should call `MeterProvider.Shutdown()` when your service is shutdown to
+ensure all records are exported. This service makes that call as part of a
+deferred function in main
+
+```go
+    mp := initMeterProvider()
+    defer func() {
+        if err := mp.Shutdown(context.Background()); err != nil {
+            log.Printf("Error shutting down meter provider: %v", err)
+        }
+    }()
+```
+
+### Adding golang runtime auto-instrumentation
+
+Golang runtime are instrumented in the main function
+
+```go
+    err := runtime.Start(runtime.WithMinimumReadMemStatsInterval(time.Second))
+    if err != nil {
+        log.Fatal(err)
+    }
+```
 
 ## Logs
 

src/recommendationservice/recommendation_server.py

@@ -68,19 +68,25 @@ def Watch(self, request, context):
 def get_product_list(request_product_ids):
     with tracer.start_as_current_span("get_product_list") as span:
         max_responses = 5
-        # fetch list of products from product catalog stub
+
+        # Formulate the list of characters to list of strings
+        request_product_ids_str = ''.join(request_product_ids)
+        request_product_ids = request_product_ids_str.split(',')
+
+        # Fetch list of products from product catalog stub
         cat_response = product_catalog_stub.ListProducts(demo_pb2.Empty())
         product_ids = [x.id for x in cat_response.products]
         span.set_attribute("app.products.count", len(product_ids))
 
+        # Create a filtered list of products excluding the products received as input
         filtered_products = list(set(product_ids) - set(request_product_ids))
         num_products = len(filtered_products)
         span.set_attribute("app.filtered_products.count", num_products)
-
         num_return = min(max_responses, num_products)
-        # sample list of indicies to return
+
+        # Sample list of indicies to return
         indices = random.sample(range(num_products), num_return)
-        # fetch product ids from indices
+        # Fetch product ids from indices
         prod_list = [filtered_products[i] for i in indices]
         return prod_list