diff --git a/.env.production.sample b/.env.production.sample
index b4ca2c6..4ee2faa 100644
--- a/.env.production.sample
+++ b/.env.production.sample
@@ -1,12 +1,23 @@
+### asciinema web app config file
+
+## Settings below that are un-commented are required, the rest is optional.
+## Values after "=" sign are taken as-is, so don't use double quotes for strings.
+
 ## Base URL of your asciinema web app instance
 BASE_URL=http://localhost:3000
 
+## Base secret key for signing cookies etc.
 ## Run `docker-compose run --rm web bundle exec rake secret`
-## and copy generated secret here
+## and copy generated secret here.
 SECRET_KEY_BASE=
 
-DATABASE_URL=postgresql://postgres@postgres/postgres
-REDIS_URL=redis://redis:6379
+## PostgreSQL connection URL.
+## Default: postgresql://postgres@postgres/postgres
+# DATABASE_URL=
+
+## Redis connection URL.
+## Default: redis://redis:6379
+# REDIS_URL=
 
 ## ID of the "demo" asciicast displayed on the homepage.
 ## Default: first public asciicast