Derive smtp_from_address from BASE_URL when no SMTP_FROM_ADDRESS set

.env.production.sample

@@ -1,8 +1,6 @@
 ## Base URL of your asciinema web app instance
 BASE_URL=http://localhost:3000
 
-MAILNAME=localhost
-
 ## Run `docker-compose run --rm web bundle exec rake secret`
 ## and copy generated secret here
 SECRET_KEY_BASE=
@@ -10,6 +8,15 @@ SECRET_KEY_BASE=
 DATABASE_URL=postgresql://postgres@postgres/postgres
 REDIS_URL=redis://redis:6379
 
+### E-mail delivery
+
+## Outgoing mail hostname, used by namshi/smtp container.
+MAILNAME=localhost
+
+## "From" field for all emails sent by this instance.
+## Default: asciinema <hello@hostname-from-base-url>
+# SMTP_FROM_ADDRESS=admin@example.com
+
 ### File store
 
 ## By default we use local filesystem dir ("uploads" in app root dir).

app/mailers/notifications.rb

@@ -1,5 +1,5 @@
 class Notifications < ActionMailer::Base
-  default from: CFG.from_email
+  default from: CFG.smtp_from_address
 
   def self.delay_login_request(user_id, token)
     delay.login_request(user_id, token)

config/cfg.rb

@@ -16,7 +16,7 @@ module Asciinema
     attribute :secret_key_base,                String
     attribute :admin_ids,                      Array[Integer]
     attribute :smtp_settings,                  Hash
-    attribute :from_email,                     String, default: "asciinema <hello@asciinema.org>"
+    attribute :smtp_from_address,              String
 
     def home_asciicast
       if home_asciicast_id
@@ -30,6 +30,10 @@ module Asciinema
       URI.parse(base_url).scheme
     end
 
+    def hostname
+      URI.parse(base_url).hostname
+    end
+
     def hostname_with_port
       uri = URI.parse(base_url)
       hwp = uri.hostname
@@ -45,6 +49,9 @@ module Asciinema
       scheme == 'https'
     end
 
+    def smtp_from_address
+      super || "asciinema <hello@#{hostname}>"
+    end
   end
 end