The document summarizes a Tokyo Rails Meetup that included a presentation on semi-automating bank transfers with Rails and Shinsei Bank. The meetup included doors opening at 19:00, a presentation from 19:30-20:10 on automating bank transfers with Rails and the Shinsei Bank API, drinks and networking from 20:10-20:40, a project show and tell from 20:40-21:20, and wrapping up at 21:20 before doors closed at 22:00. The presentation discussed using the shinseibank-ruby gem, the Thor toolkit, envchain for securely storing secrets, scheduling with the ice_cube gem, and automating monthly rent transfers with

1. Tokyo Rails Meetup #36
July 24th, 2017
19:00 - Doors Open
19:30 - Semi-automated bank transfers with Rails and
Shinsei - David Stosik
20:10 - Drinks, food, and networking
20:40 - Project Show and Tell
21:20 - Wrapping up
22:00 - Doors Close

2. Semi-Automating Bank
Transfers
With Rails and ShinseiBank-Ruby
David Stosik

3. Who am I?
David Stosik
@davidstosik
Engineer @ Cookpad
Global Team
Rails developer
French
In Japan since 2010
Video game fan

4. Disclaimers 🙏🏻
• 👶🏻 First talk
• ⏱ Last-minute prepared
• 🐞 Bugs are expected
• ⚠️ No responsibility
• ❓ Questions

5. shinseibank-ruby 🏦
• https://github.com/binzume/shinseib
ank-ruby
• December 2013 ~ July 2015
• Still works (!)
• Single file, 758 lines

9. Fork
• https://github.com/knshiro/shinseibank-ruby
• With @knshiro : Ugo Bataillard
• From need to automate operations (transfers,
accounting)
• Now a gem
• Provides CLI with Thor
• Active development: contributions are welcome!

10. Thor ⚡️
• https://github.com/erikhuda/thor
• Toolkit for building powerful command-line interfaces
• In shinseibank-ruby, allowed us to create a CLI to
perform common operations

13. envchain 🔑
• https://github.com/sorah/envchain
• By @sorah, Cookpad developer
• Securely stores secrets (Mac OS X: Keychain, Linux: Gnome’s
Keyring)
• Dynamically retrieves secrets and sets them as environment
variables
• Avoids storing secrets in clear text files

18. Difficulties
• Encoding:
• Shinsei’s Internet banking does not accept UTF-8
• String#toutf8:
This method decode MIME encoded string and convert
halfwidth katakana to fullwidth katakana. If you don't want it,
use
NKF.nkf('-wxm0', str) 🏻🏻♂️ ???
https://ruby-doc.org/stdlib-1.8.6/libdoc/nkf/rdoc/String.html#method-i-toutf8
• Testing

20. Goal 🎯
• Automate monthly rent transfer
• Open to evolutions
• Avoid issuing multiple transfers
• Security
• Keep last step manual

21. Solution
• Daily task checks if new transfer needs to be issued
• On new transfer:
• Create a transfer record with all details
• Send by email a one-time link that executes the transfer
• (Almost) No UI!
• https://github.com/davidstosik/auto_transfer

22. One-time links
Using Rails 5’s has_secure_token

26. Scheduling
Using the ice_cube gem

27. ice_cube ❄️
• https://github.com/seejohnrun/ice_cube
• Modeling schedules (events, with or without recurrence
rules)
• Powerful rule system
• Serializes to YAML, can be stored in database

30. Just a little bit more magic ✨
• Daily task that checks
schedules to issue new
transfers
• Mailer that sends email
with one-time link
• Plain text responses for
simplicity

31. Conclusions ✅
• Limits:
• Only Shinsei, not modular
• Shinsei is updating their Internet
banking! 😱
• No interface to manage
schedules
• One instance per user/account
• Learned:
• shinseibank-ruby gem uses
Shinsei’s design flaws as an
API
• CLI with Thor
• Scheduling with IceCube
• Rails 5’s has_secured_token

32. Thank you!
Feel free to ask questions.
Tokyo Rails Meetup is recruiting speakers,
please talk with us if you would like to share
your knowledge with the community.