sinatra_app

app.rb

# To start the server please use
# shotgun config.ru to have life reload
# or rackup
# plase notice that in both cases we have different port
require 'sinatra'
require 'sinatra/param'
require 'sinatra/json'

class ImageParserApp <  Sinatra::Application
  before do
    content_type 'application/json'
  end

  configure do
    set :raise_sinatra_param_exceptions, true
    set show_exceptions: false
  end

  post '/operations' do
     param :image,     String, required: true
     param :operation, String, in: ['blur', 'contrast']
     param :params, Hash

    "Logic"

  end

  error Sinatra::Param::InvalidParameterError do
    status 422
    param_name = env['sinatra.error'].param
    json( error: { param_name => 'param is invalid'})
  end
end

config.ru

require './app'
require 'rack/contrib'

use Rack::PostBodyContentTypeParser

run ImageParserApp

Gemfile

# A sample Gemfile
source "https://rubygems.org"

gem 'rack-contrib'
gem 'sinatra'
gem 'shotgun'
gem "sinatra-param", require: "sinatra/param"
gem 'sinatra-contrib'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    backports (3.6.8)
    git-version-bump (0.15.1)
    multi_json (1.12.1)
    rack (1.6.4)
    rack-contrib (1.4.0)
      git-version-bump (~> 0.15)
      rack (~> 1.4)
    rack-protection (1.5.3)
      rack
    rack-test (0.6.3)
      rack (>= 1.0)
    shotgun (0.9.2)
      rack (>= 1.0)
    sinatra (1.4.7)
      rack (~> 1.5)
      rack-protection (~> 1.4)
      tilt (>= 1.3, < 3)
    sinatra-contrib (1.4.7)
      backports (>= 2.0)
      multi_json
      rack-protection
      rack-test
      sinatra (~> 1.4.0)
      tilt (>= 1.3, < 3)
    sinatra-param (1.4.0)
      sinatra (~> 1.3)
    tilt (2.0.5)

PLATFORMS
  ruby

DEPENDENCIES
  rack-contrib
  shotgun
  sinatra
  sinatra-contrib
  sinatra-param