View Source Plug.RequestId (Plug v1.15.1)

A plug for generating a unique request id for each request.

The generated request id will be in the format "uq8hs30oafhj5vve8ji5pmp7mtopc08f".

If a request id already exists as the "x-request-id" HTTP request header, then that value will be used assuming it is between 20 and 200 characters. If it is not, a new request id will be generated.

The request id is added to the Logger metadata as :request_id and the response as the "x-request-id" HTTP header. To see the request id in your log output, configure your logger backends to include the :request_id metadata:

config :logger, :console, metadata: [:request_id]

It is recommended to include this metadata configuration in your production configuration file.

You can also access the request_id programmatically by calling Logger.metadata[:request_id]. Do not access it via the request header, as the request header value has not been validated and it may not always be present.

To use this plug, just plug it into the desired module:

plug Plug.RequestId


  • :http_header - The name of the HTTP request header to check for existing request ids. This is also the HTTP response header that will be set with the request id. Default value is "x-request-id"

    plug Plug.RequestId, http_header: "custom-request-id"