Sequeler

A simple server written in Elixir that receives a request, performs a query to a MySQL backend, and returns the response in JSON format.

It sits on top of Cowboy through a Plug layer, uses Emysql to communicate with MySQL, and uses Jazz to work with JSON.

The plan is to use Cipher, a cipher compatible with this spec. This way it can be used from Python, Ruby or Elixir apps.

There should be some tight query timeout, and maybe some injection prevention measures mainly to avoid accidents (requests are already signed).

I will use exrm to manage releases. (Seems too hacky to be used by now, too inmature yet)

I will use a custom docker image based on trenpixster docker image for elixir to ease development environment setup and use. That and some simple helper scripts to manage it. (Too much boilerplate but not really useful)

I will use custom low-level Elixir/Erlang scripts to control deploys:

• Bottler
• Harakiri

Development

• Install Elixir (sudo yum install erlang elixir on Fedora) See guide
• Getting deps mix deps.get
• Testing mix test
• Interactive console iex -S mix
• Deploy mix deploy
• etc...

Setup db for code:

    create database testdb;
    grant all privileges on testdb.* to 'testuser'@'localhost' identified by
        'testpassword' with grant option;
    flush privileges;

Open an interactive terminal with iex -S mix. That will get you a server on port 4000. Then you can play:

$ iex -S mix
Erlang/OTP 17 [erts-6.2] [source] [64-bit] [smp:2:2] [async-threads:10] [hipe] [kernel-poll:false]

Running Sequeler on http://localhost:4000
Interactive Elixir (1.0.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> k = Application.get_env(:sequeler, :key_phrase) |> Cipher.generate_key
"c7eaba361111a87f"
iex(2)> i = Application.get_env(:sequeler, :iv_phrase) |> Cipher.generate_iv
"testingphrasesfo"
iex(3)> sql = "show tables" |> URI.encode_www_form
"show+tables"
iex(4)> url = "/query?sql=" <> sql
"/query?sql=show+tables"
iex(5)> signed_url = url |> Cipher.sign_url(k,i)
"/query?sql=show+tables&signature=dN0s%2FVZJw%2FlWANRARyb0IvUBnKC1in4GEdVMI13Zy0oBr%2FHx28rNvU5q2nXOyDw%2F"
iex(6)> complete_url = "http://localhost:4000" <> signed_url |> to_char_list
'http://localhost:4000/query?sql=show+tables&signature=dN0s%2FVZJw%2FlWANRARyb0IvUBnKC1in4GEdVMI13Zy0rS%2B9o73VsFLvS6jp%2BZkBEU'
iex(7)> :httpc.request(complete_url)
{:ok,
 {{'HTTP/1.1', 200, 'OK'},
  [{'cache-control', 'max-age=0, private, must-revalidate'},
   {'connection', 'keep-alive'}, {'date', 'Mon, 10 Nov 2014 11:13:09 GMT'},
   {'server', 'Cowboy'}, {'content-length', '10'},
   {'content-type', 'application/json'}], '[["test"]]'}}

TODOS

• Get stable in production
• Complete readme
• Add to travis
• Consider packageability (yeah)
• Get time to play with docker