Add the worker to the elasticache security group.

cloudformation_templates/edx-reference-architecture.json

@@ -4070,6 +4070,14 @@
             "SourceSecurityGroupId":{
               "Ref":"EdxappServerSecurityGroup"
             }
+          },
+          {
+            "IpProtocol":"tcp",
+            "FromPort": { "Ref":"CacheNodePort" },
+            "ToPort": { "Ref":"CacheNodePort" },
+            "SourceSecurityGroupId":{
+              "Ref":"WorkerServerSecurityGroup"
+            }
           }
         ]
       }