Generate random errors in cartservice (open-telemetry#824)

* Generate random errors from cart service

* Update migration script?

* Update changelog

* Update changelog

* Add Copyright to FeatureFlagHelper.cs

---------

Co-authored-by: Carter Socha <43380952+cartersocha@users.noreply.github.com>
Co-authored-by: Juliano Costa <julianocosta89@outlook.com>

Author: 3 people

CHANGELOG.md

@@ -7,6 +7,8 @@ release.
 
 ## Unreleased
 
+* Add cartServiceFailure feature flag triggering Cart Service errors
+  ([#824](https://github.com/open-telemetry/opentelemetry-demo/pull/824))
 * [paymentservice] update JS SDKs to 1.12.0/0.38.0
   ([#853](https://github.com/open-telemetry/opentelemetry-demo/pull/853))
 * [frontend] update JS SDKs to 1.12.0/0.38.0

docker-compose.yml

@@ -91,6 +91,7 @@ services:
       - "${CART_SERVICE_PORT}"
     environment:
       - CART_SERVICE_PORT
+      - FEATURE_FLAG_GRPC_SERVICE_ADDR
       - REDIS_ADDR
       - OTEL_EXPORTER_OTLP_ENDPOINT
       - OTEL_RESOURCE_ATTRIBUTES

src/cartservice/src/Program.cs

@@ -3,6 +3,7 @@
 using System;
 
 using cartservice.cartstore;
+using cartservice.featureflags;
 using cartservice.services;
 
 using Microsoft.AspNetCore.Builder;
@@ -30,6 +31,7 @@
 Console.WriteLine("Initialization completed");
 
 builder.Services.AddSingleton<ICartStore>(cartStore);
+builder.Services.AddSingleton<FeatureFlagHelper>();
 
 // see https://opentelemetry.io/docs/instrumentation/net/getting-started/
 

src/cartservice/src/featureflags/FeatureFlagHelper.cs

@@ -0,0 +1,32 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+using System;
+using System.Threading.Tasks;
+using Oteldemo;
+
+namespace cartservice.featureflags;
+
+public class FeatureFlagHelper
+{
+    private readonly static Random Random = new Random();
+    private readonly FeatureFlagService.FeatureFlagServiceClient _featureFlagServiceClient;
+
+    public FeatureFlagHelper()
+    {
+        var featureFlagServiceUri = new Uri($"http://{Environment.GetEnvironmentVariable("FEATURE_FLAG_GRPC_SERVICE_ADDR")}");
+        var channel = Grpc.Net.Client.GrpcChannel.ForAddress(featureFlagServiceUri);
+        _featureFlagServiceClient = new FeatureFlagService.FeatureFlagServiceClient(channel);
+    }
+
+    public async Task<bool> GenerateCartError()
+    {
+        if (Random.Next(10) != 1)
+        {
+            return false;
+        }
+
+        var getFlagRequest = new GetFlagRequest { Name = "cartServiceFailure" };
+        var getFlagResponse = await _featureFlagServiceClient.GetFlagAsync(getFlagRequest);
+        return getFlagResponse.Flag.Enabled;
+    }
+}

src/cartservice/src/services/CartService.cs

@@ -3,19 +3,24 @@
 using System.Diagnostics;
 using System.Threading.Tasks;
 using Grpc.Core;
+using OpenTelemetry.Trace;
 using cartservice.cartstore;
+using cartservice.featureflags;
 using Oteldemo;
 
 namespace cartservice.services
 {
     public class CartService : Oteldemo.CartService.CartServiceBase
     {
         private readonly static Empty Empty = new Empty();
+        private readonly static ICartStore BadCartStore = new RedisCartStore("badhost:1234");
         private readonly ICartStore _cartStore;
+        private readonly FeatureFlagHelper _featureFlagHelper;
 
-        public CartService(ICartStore cartStore)
+        public CartService(ICartStore cartStore, FeatureFlagHelper featureFlagService)
         {
             _cartStore = cartStore;
+            _featureFlagHelper = featureFlagService;
         }
 
         public async override Task<Empty> AddItem(AddItemRequest request, ServerCallContext context)
@@ -52,7 +57,24 @@ public async override Task<Empty> EmptyCart(EmptyCartRequest request, ServerCall
             activity?.SetTag("app.user.id", request.UserId);
             activity?.AddEvent(new("Empty cart"));
 
-            await _cartStore.EmptyCartAsync(request.UserId);
+            try
+            {
+                if (await _featureFlagHelper.GenerateCartError())
+                {
+                    await BadCartStore.EmptyCartAsync(request.UserId);
+                }
+                else
+                {
+                    await _cartStore.EmptyCartAsync(request.UserId);
+                }
+            }
+            catch (RpcException ex)
+            {
+                Activity.Current?.RecordException(ex);
+                Activity.Current?.SetStatus(ActivityStatusCode.Error, ex.Message);
+                throw;
+            }
+
             return Empty;
         }
     }

src/featureflagservice/priv/repo/migrations/20220524172636_create_featureflags.exs

@@ -32,11 +32,17 @@ defmodule Featureflagservice.Repo.Migrations.CreateFeatureflags do
       name: "adServiceFailure",
       description: "Fail ad service requests sporadically",
       enabled: false})
+
+    repo().insert(%Featureflagservice.FeatureFlags.FeatureFlag{
+      name: "cartServiceFailure",
+      description: "Fail cart service requests sporadically",
+      enabled: false})
   end
 
   defp execute_down do
     repo().delete(%Featureflagservice.FeatureFlags.FeatureFlag{name: "productCatalogFailure"})
     repo().delete(%Featureflagservice.FeatureFlags.FeatureFlag{name: "recommendationCache"})
     repo().delete(%Featureflagservice.FeatureFlags.FeatureFlag{name: "adServiceFailure"})
+    repo().delete(%Featureflagservice.FeatureFlags.FeatureFlag{name: "cartServiceFailure"})
   end
 end