Support sticky sessions configuration (source-academy#3416)

* Add new environment variable

* Update example .env file

Author: RichDom2185

.env.example

@@ -1,6 +1,7 @@
 REACT_APP_DEPLOYMENT_NAME=Source Academy
 
 REACT_APP_BACKEND_URL=http://localhost:4000
+REACT_APP_FORWARD_LOAD_BALANCER_COOKIES=FALSE
 REACT_APP_USE_BACKEND=TRUE
 REACT_APP_USE_EMPTY_ASSET_PREFIX=FALSE
 REACT_APP_PLAYGROUND_ONLY=FALSE

src/commons/utils/Constants.ts

@@ -21,6 +21,11 @@ const storiesBackendUrl = process.env.REACT_APP_STORIES_BACKEND_URL;
 const cadetLoggerUrl = isTest ? undefined : process.env.REACT_APP_CADET_LOGGER;
 const cadetLoggerInterval = parseInt(process.env.REACT_APP_CADET_LOGGER_INTERVAL || '10000', 10);
 const useBackend = !isTest && isTrue(process.env.REACT_APP_USE_BACKEND);
+/**
+ * Whether or not attach cookies to every API call. Useful for load balancers that
+ * route requests based on cookies (e.g. for sticky sessions).
+ */
+const forwardLoadBalancerCookies = isTrue(process.env.REACT_APP_FORWARD_LOAD_BALANCER_COOKIES);
 const useEmptyAssetPrefix = isTrue(process.env.REACT_APP_USE_EMPTY_ASSET_PREFIX);
 const defaultSourceChapter = Chapter.SOURCE_4;
 const defaultSourceVariant = Variant.DEFAULT;
@@ -158,6 +163,7 @@ const Constants = {
   storiesBackendUrl,
   cadetLoggerUrl,
   useBackend,
+  forwardLoadBalancerCookies,
   useEmptyAssetPrefix,
   defaultSourceChapter,
   defaultSourceVariant,

src/commons/utils/RequestHelper.tsx

@@ -51,6 +51,10 @@ export const request = async (
   opts: RequestOptions,
   rawUrl?: string
 ): Promise<Response | null> => {
+  if (Constants.forwardLoadBalancerCookies) {
+    // Always attach cookies to every API call
+    opts.withCredentials = true;
+  }
   const fetchOptions = generateApiCallHeadersAndFetchOptions(method, opts);
 
   try {