rate-service

note: Ruby sucks. I'm tired of fighting to update this when a simple patch version bump of one dependency takes a full 1/2 hour debugging session due to gem/bundler issues. This is a terrible ecosystem. I'll try and make a Go version soon, but this service is no longer supported, please use at your own risk. There is a known rack vulnerability which I can't bother to update (again, because the Ruby software ecosystem sucks).

An exchange rate API for converting rates between various fiat and crypto-currency sources.

Abstracting this functionality to a separate service seemed like the best design choice for various software projects that I've been working on.

Currently only uses Poloniex spot price and doesn't consider volume/VWAP, etc., so there's a bit of work to be done.

Deployment via Docker

0. Install docker and docker-compose. Note that Ubuntu is notoriously slow in their package release process, and because of this, the docker-compose installed with apt-get on Ubuntu 16.10 won't work with this setup. I recommend installing the latest docker-compose ELF binary which is available on Github.

1. Clone the repo:

   git clone https://github.com/nmarley/rate-service.git && cd rate-service

2. Create the environment variables file nginx-variables.env with the appropriate values:

   NGINX_HOST=FQDN
   NGINX_SSL_CERT=/ssl/rates.cer
   NGINX_SSL_KEY=/ssl/rates.key
   NGINX_DHPARAM=/ssl/dh2048.pem
   

3. Add SSL certificate info to /data/ssl on the host machine (or alter the docker-compose.yml file accordingly). You can generate a DH params file by: openssl dhparam -out dh2048.pem 2048. Obtain SSL certificates in the usual manner (I recommend Let's Encrypt).

4. Start all containers:

   docker-compose up

5. Ensure a scheduled cron (or other) job is calling this API endpoint every minute, in order to pull the latest exchange rate data:

   http://<service>/service/ingest

Example:

curl -I http://localhost/service/ingest;echo

The endpoint doesn't have to be called from the Docker host -- it can be reached from anywhere.

That's it! Make sure and test the configuration.

Install via traditional manner

Clone this repo and install gems:

git clone https://github.com/nmarley/rate-service.git && cd rate-service
bundle install --binstubs --path vendor

Also install & run Redis on the standard port.

Run this cron command to fetch rates every minute:

# m h  dom mon dow   command
* * * * * /bin/bash <path-to-repo>/fetch-current-rates.sh >/dev/null 2>&1

Run the sinatra app using whatever deployment method:

bundle exec puma -C config/puma.rb config.ru &

You can put this behind an nginx reverse proxy:

  upstream rate {
    server 127.0.0.1:4568;
  }

  server {
      server_name rates.example.com;
      listen 80;

      location /rate {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_pass http://rate;
      }
  }