in gems/aws-sigv4/lib/aws-sigv4/signer.rb [64:79]
def initialize(options = {})
@service = extract_service(options)
@region = extract_region(options)
@credentials_provider = extract_credentials_provider(options)
@unsigned_headers = Set.new((options.fetch(:unsigned_headers, []))
.map(&:downcase))
@unsigned_headers << 'authorization'
@unsigned_headers << 'x-amzn-trace-id'
@unsigned_headers << 'expect'
@uri_escape_path = options.fetch(:uri_escape_path, true)
@apply_checksum_header = options.fetch(:apply_checksum_header, true)
@signing_algorithm = options.fetch(:signing_algorithm, :sigv4)
@normalize_path = options.fetch(:normalize_path, true)
@omit_session_token = options.fetch(:omit_session_token, false)
end