LogTenSafe: Rails Back-End

LogTenSafe is a website (at logtensafe.com) and a macOS application that backs up logbook data from LogTen Pro, in case iCloud sync poops the bed, or some other unforeseen badness happens.

This project is the back-end for the LogTenSafe website. The back-end is powered by Ruby on Rails. It is an API-only back-end, with the front-end and application being in entirely separate repositories. This back-end stores user and backup data, and renders API responses and WebSocket connections.

Installation and Usage

LogTenSafe is a straightforward API-only Rails site. The targeted Ruby version is in .ruby-version. Run brew install to install all other required dependencies with Homebrew (or inspect the contents of Brewfile manually), then run bundle install to install all required gems.

You will also need to generate your own credentials.yml.enc and master.key files using the rails credentials:edit task. The YAML should be of the following format:

secret_key_base:

aws:
  access_key_id:
  secret_access_key:

bugsnag_api_key:

devise:
  key_base:
  jwt_secret_key:

Run rails server to run the back-end server. Note that the front-end expects the back-end to be running on port 5000 in development, for the development proxy to work. Run bin/cable to start the WebSockets server on port 28080.

YARD documentation is generated to the doc/ directory by running rails yard.

Architecture

The LogTenSafe back-end stores user and backup data, analyzes logbook data, and exposes that information via HTTP and WebSockets APIs.

Models

There are two models in LogTenSafe, {User} and {Backup}. A User has many Backups, one for each logbook that is uploaded. A validation on Backup ensures that duplicate logbooks are not uploaded twice.

Data Store

After being uploaded, the logbook is stored to AWS using Active Storage. The {LogbookAnalyzer} Active Storage analyzer loads the logbook using SQLite, and performs queries to calculate a summary of the logbook data, which is saved to the blob metadata.

Jobs

Offline processing is powered by Sidekiq. There are no application-specific jobs, only the default jobs that perform Active Storage analysis, etc.

API

This website exposes a JSON API for getting user and backup information, and uploading or deleting backups. Downloading backups is also possible using the expiring URL system exposed by Active Storage.

Authorization

Authorization is handled by Devise, which provides the routes for signing up, logging in, retrieving passwords, etc.

Authorization is mediated using JSON Web Tokens (JWT). When a user logs in, the response will have an Authorization header containing the JWT. That JWT can be used in the Authorization header of subsequent requests to authenticate those requests, until it expires.

WebSockets

By making an HTTP Upgrade request to /cable on the WebSockets server, the client can open a connection Action Cable. Action Cable has one channel, BackupsChannel, which streams any additions, deletions, or changes to the user's list of backups.

The WebSockets must be authenticated using the JWT, passed as a query parameter to /cable.

Testing

Unit tests are written using RSpec, and can be run by executing rspec spec. E2E tests are handled by the front-end.