Specify payload file using CLI arg for deliver.rb

deliver.rb

@@ -1,9 +1,11 @@
+#!/usr/bin/ruby
+
 # https://blog.joinmastodon.org/2018/06/how-to-implement-a-basic-activitypub-server/
 
 require 'http'
 require 'openssl'
 
-document      = File.read('message')
+document      = File.read(ARGV[0])
 date          = Time.now.utc.httpdate
 keypair       = OpenSSL::PKey::RSA.new(File.read('private.pem'))
 signed_string = "(request-target): post /inbox\nhost: git.exozy.me\ndate: #{date}"