cowboy_telemetry

Telemetry instrumentation for the Cowboy HTTP server.

This package contains a cowboy_stream handler that will instrument each request and emit telemetry events.

Usage

Configure your cowboy server with the cowboy_telemetry_h stream handler first.

cowboy:start_clear(http, [{port, Port}], #{
    env => #{dispatch => Dispatch},
    stream_handlers => [cowboy_telemetry_h, cowboy_stream_h]
}.

Telemetry Events

`[cowboy, request, start]`

A span event emitted at the beginning of a request.

measurements: #{system_time => erlang:system_time()}
metadata: #{stream_id => cowboy_stream:streamid(), req => cowboy_req:req()}

`[cowboy, request, stop]`

A span event emitted at the end of a request.

measurements: measurements()
metadata: metadata()

If the request is terminated early - by the client or by the server - before a response is sent, the metadata will also contain an error:

metadata: metadata() + #{error => cowboy_stream:reason()}

`[cowboy, request, exception]`

A span event emitted if the request process exits.

measurements: measurements()
metadata: metadata() + #{kind => exit, stacktrace => list()}

`[cowboy, request, early_error]`

A single event emitted when Cowboy itself returns an early_error response before executing any handlers.

measurements: #{system_time => erlang:system_time(), resp_body_length => non_neg_integer()}
metadata: metadata() without procs or informational

Types

measurements():
- duration :: req_start - req_end see cowboy_metrics_h
- req_body_duration :: req_body_start - req_body_end see cowboy_metrics_h
- resp_duration :: resp_start - resp_end see cowboy_metrics_h
- req_body_length :: non_neg_integer()
- resp_body_length :: non_neg_integer()
metadata():
- pid, streamid, req, resp_headers, resp_status, and ref from cowboy_metrics_h:metrics()
cowboy_metrics_h:metrics(): Defined in cowboy_metrics_h

Note:

The telemetry handlers are executed from the cowboy connection process, not from the request process.

hrzndhrn / cowboy_telemetry Goto Github PK