cowboy_req:inform - Send an informational response


inform(Status, Req :: cowboy_req:req())
    -> inform(StatusCode, #{}, Req)

inform(Status, Headers, Req :: cowboy_req:req())
    -> ok

Status  :: cowboy:http_status()
Headers :: cowboy:http_headers()

Send an informational response.

Informational responses use a status code between 100 and 199. They cannot include a body. This function will not use any of the previously set headers. All headers to be sent must be given directly.

Any number of informational responses can be sent as long as they are sent before the proper response. Attempting to use this function after sending a normal response will result in an error.

The header names must be given as lowercase binary strings. While header names are case insensitive, Cowboy requires them to be given as lowercase to function properly.



The status code for the response.


The response headers.

Header names must be given as lowercase binary strings.


The Req object.

Return value

The atom ok is always returned. It can be safely ignored.


  • 2.1: Function introduced.


Send an informational response
Req = cowboy_req:inform(102, Req0).
Send an informational response with headers
Req = cowboy_req:inform(103, #{
    <<"link">> => <<"</style.css>; rel=preload; as=style">>,
    <<"link">> => <<"</script.js>; rel=preload; as=script">>
}, Req0).

See also

cowboy_req(3), cowboy_req:reply(3), cowboy_req:stream_reply(3), cowboy_req:push(3)

Cowboy 2.7 Function Reference


Version select

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