Class: Rack::S3

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/s3.rb

Overview

Serve static s3 content, like Rack::Files

Instance Method Summary collapse

Constructor Details

#initialize(url: nil, bucket: nil, prefix: nil, client: Aws::S3::Client.new) ⇒ S3

Returns a new instance of S3.



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# File 'lib/rack/s3.rb', line 8

def initialize(url: nil, bucket: nil, prefix: nil, client: Aws::S3::Client.new)
  if url
    uri = URI.parse(url)
    raise "Not an S3 url" unless uri.scheme == "s3"
    bucket = uri.host
    prefix = uri.path.delete_prefix("/")
  end

  prefix = nil if prefix == "" || prefix == "/"

  @bucket = bucket
  @prefix = prefix
  @client = client
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/rack/s3.rb', line 23

def call(env)
  request = Rack::Request.new(env)

  # Only allow GET
  return error(405, { "Allow" => "GET" }) unless request.get?

  # Don't allow odd encodings in paths
  path_info = Rack::Utils.unescape_path request.path_info
  return error(400) unless Rack::Utils.valid_path?(path_info)

  # Redirect when logical uri path ends with a slash, but not really
  # i.e. mount Rack::S3.new(...), at: "blah" # => /blah => /blah/
  if (path_info.nil? || path_info.empty? || path_info.end_with?("/")) && !request.fullpath.end_with?("/")
    return redirect(request.fullpath + "/")
  end

  # Rails routes with mount "/blah" => Rack::S3.new(...), and a request to
  # "/blah" produces a script_path of "/blah" and path_info of "/". If we
  # serve an index.html at that uri then relative references will not work.
  # So consult the request_path, if we can, to double check.
  if env["REQUEST_PATH"] && request.fullpath.end_with?("/") && !env["REQUEST_PATH"].end_with?("/")
    return redirect(request.fullpath)
  end

  # Reject any traversals, etc
  clean_path = Rack::Utils.clean_path_info(path_info)
  return error(400) unless clean_path == path_info

  key = path_info.delete_prefix("/")

  key = "#{@prefix}/#{key}" if @prefix

  # Basic index file support
  if key.empty? || key.end_with?("/")
    key << "index.html"
  end

  # It would be nice to only head the object if we need to (if modified
  # since, etc), but aws-sdk-s3 doesn't expose a nice way to get an object,
  # use its response headers, and then stream the body -- you can only
  # receive a response with a buffered body, or stream the body before
  # getting the headers.
  head = @client.head_object(bucket: @bucket, key: key)

  etag = head.etag
  if none_match = request.get_header("HTTP_IF_NONE_MATCH")
    return not_modified if none_match == etag
  end

  last_modified = head.last_modified.httpdate
  if modified_since = request.get_header("HTTP_IF_MODIFIED_SINCE")
    return not_modified if modified_since == last_modified
  end

  headers = {
    "Content-Length" => head.content_length.to_s,
    "Content-Type" => head.content_type,
    "ETag" => etag,
    "Last-Modified" => last_modified,
  }

  body = Enumerator.new do |enum|
    @client.get_object(bucket: @bucket, key: key) do |chunk|
      enum.yield chunk
    end
  end

  [200, headers, body]
rescue Aws::S3::Errors::Forbidden
  error(403)
rescue Aws::S3::Errors::NotFound
  error(404)
end