Class: Swirl::AWS

Inherits:
Object
  • Object
show all
Includes:
Helpers::Compactor, Helpers::Expander
Defined in:
lib/swirl/aws.rb

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Helpers::Expander

expand

Methods included from Helpers::Compactor

compact, compact!

Constructor Details

#initialize(*args) ⇒ AWS

Returns a new instance of AWS.



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# File 'lib/swirl/aws.rb', line 38

def initialize(*args)
  opts = args.last.is_a?(Hash) ? args.pop : Hash.new
  name = args.shift

  service = self.class.services[name] || {}
  opts    = service.merge(opts)

  @url = URI(opts[:url]) ||
    raise(ArgumentError, "No url given")

  if region = opts[:region]
    parts = URI.split(@url.to_s)
    parts[2] = parts[2].split('.').insert(1, region).join('.')
    @url = URI::HTTPS.new(*parts)
  end

  @version = opts[:version] ||
    raise(ArgumentError, "No version given")

  @aws_access_key_id  = \
    opts[:aws_access_key_id] ||
    ENV["AWS_ACCESS_KEY_ID"] ||
    raise(ArgumentError, "No aws_access_key_id given")

  @aws_secret_access_key = \
    opts[:aws_secret_access_key] ||
    ENV["AWS_SECRET_ACCESS_KEY"] ||
    raise(ArgumentError, "No aws_secret_access_key given")

  @hmac = HMAC::SHA256.new(@aws_secret_access_key)
end

Class Method Details

.service(name, url, version) ⇒ Object 



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# File 'lib/swirl/aws.rb', line 28

def self.service(name, url, version)
  @services[name] = { :url => url, :version => version }
end

.services ⇒ Object 



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# File 'lib/swirl/aws.rb', line 23

def self.services
  # This must be modified using `service`
  @services.dup
end

Instance Method Details

#call(action, query = {}, &blk) ⇒ Object

Execute an EC2 command, expand the input, and compact the output

Examples:

ec2.call("DescribeInstances")
ec2.call("TerminateInstances", "InstanceId" => ["i-1234", "i-993j"]



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# File 'lib/swirl/aws.rb', line 95

def call(action, query={}, &blk)
  call!(action, expand(query)) do |code, data|
    case code
    when 200
      response = compact(data)
    when 400...500
      messages = if data["Response"]
        Array(data["Response"]["Errors"]).map {|_, e| e["Message"] }
      elsif data["ErrorResponse"]
        Array(data["ErrorResponse"]["Error"]["Code"])
      end
      raise InvalidRequest, messages.join(",")
    else
      msg = "unexpected response #{code} -> #{data.inspect}"
      raise InvalidRequest, msg
    end

    if blk
      blk.call(response)
    else
      response
    end
  end
end

#call!(action, query = {}, &blk) ⇒ Object 



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# File 'lib/swirl/aws.rb', line 120

def call!(action, query={}, &blk)
  log "Action: #{action}"
  log "Query:  #{query.inspect}"

  # Hard coding this here until otherwise needed
  method = "POST"

  query["Action"] = action
  query["AWSAccessKeyId"] = @aws_access_key_id
  query["SignatureMethod"] = "HmacSHA256"
  query["SignatureVersion"] = "2"
  query["Timestamp"] = Time.now.utc.strftime("%Y-%m-%dT%H:%M:%SZ")
  query["Version"] = @version

  body = compile_sorted_form_data(query)
  body += "&" + ["Signature", compile_signature(method, body)].join("=")

  post(body) do |code, xml|
    log "HTTP Response Code: #{code}"
    log xml.gsub("\n", "\n[swirl] ")

    data = Crack::XML.parse(xml)
    blk.call(code, data)
  end
end

#compile_signature(method, body) ⇒ Object 



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# File 'lib/swirl/aws.rb', line 80

def compile_signature(method, body)
  string_to_sign = [method, @url.host, "/", body] * "\n"
  hmac = @hmac.update(string_to_sign)
  encoded_sig = Base64.encode64(hmac.digest).chomp
  escape(encoded_sig)
end

#compile_sorted_form_data(query) ⇒ Object 



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# File 'lib/swirl/aws.rb', line 75

def compile_sorted_form_data(query)
  valid = query.reject {|_, v| v.nil? }
  valid.sort.map {|k,v| [k, escape(v)] * "=" } * "&"
end

#escape(value) ⇒ Object 



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# File 'lib/swirl/aws.rb', line 71

def escape(value)
  CGI.escape(value).gsub(/\+/, "%20")
end

#inspect ⇒ Object 



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# File 'lib/swirl/aws.rb', line 160

def inspect
  "<#{self.class.name} version: #{@version} url: #{@url} aws_access_key_id: #{@aws_access_key_id}>"
end

#log(msg) ⇒ Object 



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# File 'lib/swirl/aws.rb', line 164

def log(msg)
  if ENV["SWIRL_LOG"]
    $stderr.puts "[swirl] #{msg}"
  end
end

#post(body, &blk) ⇒ Object 



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# File 'lib/swirl/aws.rb', line 146

def post(body, &blk)
  headers = { "Content-Type" => "application/x-www-form-urlencoded" }

  http = Net::HTTP.new(@url.host, @url.port)
  http.use_ssl = true
  http.verify_mode = OpenSSL::SSL::VERIFY_NONE

  request = Net::HTTP::Post.new(@url.request_uri, headers)
  request.body = body

  response = http.request(request)
  blk.call(response.code.to_i, response.body)
end