cowboy_http - HTTP/1.1


The module cowboy_http implements HTTP/1.1 and HTTP/1.0 as a Ranch protocol.


opts() :: #{
    connection_type         => worker | supervisor,
    env                     => cowboy_middleware:env(),
    idle_timeout            => timeout(),
    inactivity_timeout      => timeout(),
    linger_timeout          => timeout(),
    max_empty_lines         => non_neg_integer(),
    max_header_name_length  => non_neg_integer(),
    max_header_value_length => non_neg_integer(),
    max_headers             => non_neg_integer(),
    max_keepalive           => non_neg_integer(),
    max_method_length       => non_neg_integer(),
    max_request_line_length => non_neg_integer(),
    max_skip_body_length    => non_neg_integer(),
    middlewares             => [module()],
    request_timeout         => timeout(),
    shutdown_timeout        => timeout(),
    stream_handlers         => [module()]

Configuration for the HTTP/1.1 protocol.

This configuration is passed to Cowboy when starting listeners using cowboy:start_clear/3 or cowboy:start_tls/3 functions.

It can be updated without restarting listeners using the Ranch functions ranch:get_protocol_options/1 and ranch:set_protocol_options/2.

The default value is given next to the option name:

connection_type (supervisor)

Whether the connection process also acts as a supervisor.

env (#{})

Middleware environment.

idle_timeout (60000)

Time in ms with no data received before Cowboy closes the connection.

inactivity_timeout (300000)

Time in ms with nothing received at all before Cowboy closes the connection.

linger_timeout (1000)

Time in ms that Cowboy will wait when closing the connection. This is necessary to avoid the TCP reset problem as described in the section 6.6 of RFC7230.

max_empty_lines (5)

Maximum number of empty lines before a request.

max_header_name_length (64)

Maximum length of header names.

max_header_value_length (4096)

Maximum length of header values.

max_headers (100)

Maximum number of headers allowed per request.

max_keepalive (100)

Maximum number of requests allowed per connection.

max_method_length (32)

Maximum length of the method.

max_request_line_length (8000)

Maximum length of the request line.

max_skip_body_length (1000000)

Maximum length Cowboy is willing to skip when the user code did not read the body fully. When the remaining length is too large or unknown Cowboy will close the connection.

middlewares ([cowboy_router, cowboy_handler])

Middlewares to run for every request.

request_timeout (5000)

Time in ms with no requests before Cowboy closes the connection.

shutdown_timeout (5000)

Time in ms Cowboy will wait for child processes to shut down before killing them.

stream_handlers ([cowboy_stream_h])

Ordered list of stream handlers that will handle all stream events.


  • 2.5: The linger_timeout option was added.
  • 2.2: The max_skip_body_length option was added.
  • 2.0: The timeout option was renamed request_timeout.
  • 2.0: The idle_timeout, inactivity_timeout and shutdown_timeout options were added.
  • 2.0: The max_method_length option was added.
  • 2.0: The max_request_line_length default was increased from 4096 to 8000.
  • 2.0: The connection_type option was added.
  • 2.0: The env option is now a map instead of a proplist.
  • 2.0: The stream_handlers option was added.
  • 2.0: The compress option was removed in favor of the cowboy_compress_h stream handler.
  • 2.0: Options are now a map instead of a proplist.
  • 2.0: Protocol introduced. Replaces cowboy_protocol.

See also

cowboy(7), cowboy_http2(3), cowboy_websocket(3)

Cowboy 2.5 Function Reference


Version select

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