fix: Set environment variables required to run the app

Author: akash1810

dotcom-rendering/cdk/lib/__snapshots__/renderingStack.test.ts.snap

@@ -2138,6 +2138,24 @@ exports[`The RenderingCDKStack matches the snapshot for Tag Page Rendering CODE
                 "Ref": "RiffRaffDeploymentId",
               },
             },
+            "Environment": [
+              {
+                "Name": "NODE_ENV",
+                "Value": "production",
+              },
+              {
+                "Name": "GU_STAGE",
+                "Value": "CODE",
+              },
+              {
+                "Name": "GU_APP",
+                "Value": "tag-page-rendering",
+              },
+              {
+                "Name": "GU_STACK",
+                "Value": "frontend",
+              },
+            ],
             "Essential": true,
             "Image": {
               "Fn::Join": [

dotcom-rendering/cdk/lib/renderingStack.ts

@@ -295,6 +295,22 @@ export class RenderingCDKStack extends CDKStack {
 					}),
 		});
 
+		if (imageIdentifier != null) {
+			const ecsEnvVars: Record<string, string> = {
+				NODE_ENV: 'production',
+				GU_STAGE: stage,
+				GU_APP: guApp,
+				GU_STACK: guStack,
+			};
+
+			for (const [key, value] of Object.entries(ecsEnvVars)) {
+				app.ecsService?.taskDefinition.defaultContainer?.addEnvironment(
+					key,
+					value,
+				);
+			}
+		}
+
 		/**
 		 * The default Node server keep alive timeout is 5 seconds
 		 * @see https://nodejs.org/api/http.html#serverkeepalivetimeout