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require "securerandom"
require "active_support/core_ext/string/access"
module ActionDispatch
# Makes a unique request id available to the action_dispatch.request_id env variable (which is then accessible through
# ActionDispatch::Request#uuid or the alias ActionDispatch::Request#request_id) and sends the same id to the client via the X-Request-Id header.
#
# The unique request id is either based on 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
X_REQUEST_ID = "X-Request-Id".freeze # :nodoc:
def initialize(app)
@app = app
end
def call(env)
req = ActionDispatch::Request.new env
req.request_id = make_request_id(req.x_request_id)
@app.call(env).tap { |_status, headers, _body| headers[X_REQUEST_ID] = req.request_id }
end
private
def make_request_id(request_id)
if request_id.presence
request_id.gsub(/[^\w\-]/, "".freeze).first(255)
else
internal_request_id
end
end
def internal_request_id
SecureRandom.uuid
end
end
end