flush specific redis namespaces via rake (#421)

* flush specific redis namespaces via rake

* minor fix

* allow rake task to invoke environment for models

lib/tasks/redis.rake

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+namespace :redis do
+  desc 'Flush Vets.gov User/Sessions'
+  task flush_session: [:flush_session_store, :flush_users_store]
+
+  desc 'Flush RedisStore: Session'
+  task flush_session_store: :environment do
+    namespace = Session.new.redis_namespace.namespace
+    redis = Redis.current
+    redis.scan_each(match: "#{namespace}:*") do |key|
+      redis.del(key)
+    end
+  end
+
+  desc 'Flush RedisStore: User'
+  task flush_users_store: :environment do
+    namespace = User.new.redis_namespace.namespace
+    redis = Redis.current
+    redis.scan_each(match: "#{namespace}:*") do |key|
+      redis.del(key)
+    end
+  end
+end