Skip to content
Find file
Fetching contributors…
Cannot retrieve contributors at this time
40 lines (34 sloc) 1.43 KB
require 'securerandom'
require 'active_support/core_ext/string/access'
require 'active_support/core_ext/object/blank'
module ActionDispatch
# Makes a unique request id available to the action_dispatch.request_id env variable (which is then accessible through
# ActionDispatch::Request#uuid) and sends the same id to the client via the X-Request-Id header.
# The unique request id is either based off the X-Request-Id header in the request, which would typically be generated
# by a firewall, load balancer, or the web server, or, if this header is not available, a random uuid. If the
# header is accepted from the outside world, we sanitize it to a max of 255 chars and alphanumeric and dashes only.
# The unique request id can be used to trace a request end-to-end and would typically end up being part of log files
# from multiple pieces of the stack.
class RequestId
def initialize(app)
@app = app
def call(env)
env["action_dispatch.request_id"] = external_request_id(env) || internal_request_id
status, headers, body =
headers["X-Request-Id"] = env["action_dispatch.request_id"]
[ status, headers, body ]
def external_request_id(env)
if request_id = env["HTTP_X_REQUEST_ID"].presence
request_id.gsub(/[^\w\-]/, "").first(255)
def internal_request_id
Something went wrong with that request. Please try again.