add feature flags on start (open-telemetry#314)

* add feature flags on start

* revert sleep change

* document feature flags

* feature flag definitions

* Revert "document feature flags"

This reverts commit c975f5d.

* document feature flags

* document feature flags

* add reference to feature flags

* fix nits

CHANGELOG.md

@@ -75,6 +75,8 @@ significant modifications will be credited to OpenTelemetry Authors.
 ([#245](https://github.com/open-telemetry/opentelemetry-demo/pull/245))
 * Added Frontend Instrumentation
 ([#293](https://github.com/open-telemetry/opentelemetry-demo/pull/293))
+* Add Feature Flags definitions
+([#314](https://github.com/open-telemetry/opentelemetry-demo/pull/314))
 * Enable Locust loadgen environment variable config options
 ([#316](https://github.com/open-telemetry/opentelemetry-demo/pull/316))
 * Simplified and cleaned up ProductCatalogService

README.md

@@ -19,6 +19,7 @@ This repo is a work in progress. If you'd like to help, check out our
 ## Documentation
 
 - [Demo Screenshots](./docs/demo_screenshots.md)
+- [Feature Flags](./docs/feature_flags.md)
 - [Manual Span Attributes](./docs/manual_span_attributes.md)
 - [Metric Feature Coverage by Service](./docs/metric_service_features.md)
 - [Requirements](./docs/requirements/README.md)

docs/feature_flags.md

@@ -0,0 +1,11 @@
+# Feature Flags
+
+This demo comes with several feature flags which can control failure conditions
+in specific services. By default the flags are disabled. Using the Feature Flags
+UI <http://localhost:8081> you will be able to control the status of these
+feature flags.
+
+| Feature Flag            | Service(s)      | Description                                                               |
+|-------------------------|-----------------|---------------------------------------------------------------------------|
+| `productCatalogFailure` | Product Catalog | Generate an error for `GetProduct` requests with product id: `OLJCESPC7Z` |
+| `shippingFailure`       | Shipping        | Induce very long latency when shipping outside of USA                     |

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

@@ -11,5 +11,24 @@ defmodule Featureflagservice.Repo.Migrations.CreateFeatureflags do
     end
 
     create unique_index(:featureflags, [:name])
+
+    execute(&execute_up/0, &execute_down/0)
+  end
+
+  defp execute_up do
+    repo().insert(%Featureflagservice.FeatureFlags.FeatureFlag{
+      name: "productCatalogFailure",
+      description: "Fail product catalog service on a specific product",
+      enabled: false})
+
+    repo().insert(%Featureflagservice.FeatureFlags.FeatureFlag{
+      name: "shippingFailure",
+      description: "Fail shipping service when shipping a product to a non-USA address",
+      enabled: false})
+  end
+
+  defp execute_down do
+    repo().delete(%Featureflagservice.FeatureFlags.FeatureFlag{name: "productCatalogFailure"})
+    repo().delete(%Featureflagservice.FeatureFlags.FeatureFlag{name: "shippingFailure"})
   end
 end