defmodule NewRelic.Telemetry.Plug do
use GenServer
@moduledoc """
Provides `Plug` instrumentation via `telemetry`.
Plug pipelines are auto-discovered and instrumented.
We automatically gather:
* Transaction metrics and events
* Transaction Traces
* Distributed Traces
You can opt-out of this instrumentation via configuration. See `NewRelic.Config` for details.
----
To prevent reporting an individual transaction:
```elixir
NewRelic.ignore_transaction()
```
----
Inside a Transaction, the agent will track work across processes that are spawned and linked.
You can signal to the agent not to track work done inside a spawned process, which will
exclude it from the current Transaction.
To exclude a process from the Transaction:
```elixir
Task.async(fn ->
NewRelic.exclude_from_transaction()
Work.wont_be_tracked()
end)
```
"""
alias NewRelic.{Transaction, DistributedTrace, Util}
@doc false
def start_link(_) do
config = %{
enabled?: NewRelic.Config.feature?(:plug_instrumentation),
handler_id: {:new_relic, :plug}
}
GenServer.start_link(__MODULE__, config, name: __MODULE__)
end
@cowboy_start [:cowboy, :request, :start]
@cowboy_stop [:cowboy, :request, :stop]
@cowboy_exception [:cowboy, :request, :exception]
@plug_router_start [:plug, :router_dispatch, :start]
@plug_events [
@cowboy_start,
@cowboy_stop,
@cowboy_exception,
@plug_router_start
]
@doc false
def init(%{enabled?: false}), do: :ignore
def init(%{enabled?: true} = config) do
:telemetry.attach_many(
config.handler_id,
@plug_events,
&__MODULE__.handle_event/4,
config
)
Process.flag(:trap_exit, true)
{:ok, config}
end
@doc false
def terminate(_reason, %{handler_id: handler_id}) do
:telemetry.detach(handler_id)
end
@doc false
def handle_event(
@cowboy_start,
%{system_time: system_time},
meta,
_config
) do
Transaction.Reporter.start_transaction(:web)
if NewRelic.Config.enabled?(),
do: DistributedTrace.start(:http, meta.req.headers)
add_start_attrs(meta, system_time)
maybe_report_queueing(meta)
end
def handle_event(
@plug_router_start,
_measurements,
%{conn: conn, route: route},
_config
) do
NewRelic.add_attributes(plug_name: plug_name(conn, route))
end
def handle_event(
@cowboy_stop,
%{duration: duration} = meas,
meta,
_config
) do
add_stop_attrs(meas, meta, duration)
add_stop_error_attrs(meta)
Transaction.Reporter.stop_transaction(:web)
end
# Don't treat 404 as an exception
def handle_event(
@cowboy_exception,
%{duration: duration} = meas,
%{resp_status: "404" <> _} = meta,
_config
) do
add_stop_attrs(meas, meta, duration)
Transaction.Reporter.stop_transaction(:web)
end
def handle_event(
@cowboy_exception,
%{duration: duration} = meas,
%{kind: kind} = meta,
_config
) do
add_stop_attrs(meas, meta, duration)
{reason, stack} = reason_and_stack(meta)
Transaction.Reporter.fail(%{kind: kind, reason: reason, stack: stack})
Transaction.Reporter.stop_transaction(:web)
end
def handle_event(_event, _measurements, _meta, _config) do
:ignore
end
defp add_start_attrs(meta, system_time) do
[
pid: inspect(self()),
system_time: system_time,
host: meta.req.host,
path: meta.req.path,
remote_ip: meta.req.peer |> elem(0) |> :inet_parse.ntoa() |> to_string(),
referer: meta.req.headers["referer"],
user_agent: meta.req.headers["user-agent"],
content_type: meta.req.headers["content-type"],
request_method: meta.req.method
]
|> NewRelic.add_attributes()
end
@kb 1024
defp add_stop_attrs(meas, meta, duration) do
info = Process.info(self(), [:memory, :reductions])
[
duration: duration,
status: status_code(meta),
memory_kb: info[:memory] / @kb,
reductions: info[:reductions],
"cowboy.req_body_duration_ms": meas[:req_body_duration] |> to_ms,
"cowboy.resp_duration_ms": meas[:resp_duration] |> to_ms,
"cowboy.req_body_length": meas[:req_body_length],
"cowboy.resp_body_length": meas[:resp_body_length]
]
|> NewRelic.add_attributes()
end
defp add_stop_error_attrs(%{resp_status: "5" <> _, error: {:socket_error, error, message}}) do
[
error: true,
"cowboy.socket_error": error,
"cowboy.socket_error.message": message
]
|> NewRelic.add_attributes()
end
# client timeout:
defp add_stop_error_attrs(%{error: {:socket_error, error, message}}) do
[
"cowboy.socket_error": error,
"cowboy.socket_error.message": message
]
|> NewRelic.add_attributes()
end
# server timeout:
defp add_stop_error_attrs(%{error: {:connection_error, error, message}}) do
[
"cowboy.connection_error": error,
"cowboy.connection_error.message": message
]
|> NewRelic.add_attributes()
end
defp add_stop_error_attrs(_meta) do
:ok
end
defp to_ms(duration),
do: System.convert_time_unit(duration, :native, :microsecond) / 1000
@request_start_header "x-request-start"
defp maybe_report_queueing(meta) do
with true <- NewRelic.Config.feature?(:request_queuing_metrics),
request_start when is_binary(request_start) <- meta.req.headers[@request_start_header],
{:ok, request_start_s} <- Util.RequestStart.parse(request_start) do
NewRelic.add_attributes(request_start_s: request_start_s)
end
end
defp status_code(%{resp_status: :undefined}) do
nil
end
defp status_code(%{resp_status: status})
when is_integer(status) do
status
end
defp status_code(%{resp_status: status})
when is_binary(status) do
String.split(status) |> List.first() |> String.to_integer()
end
defp reason_and_stack(%{reason: %{__exception__: true} = reason, stacktrace: stack}) do
{reason, stack}
end
defp reason_and_stack(%{reason: {{reason, stack}, _init_call}}) do
{reason, stack}
end
defp reason_and_stack(%{reason: {reason, _init_call}}) do
{reason, []}
end
defp reason_and_stack(unexpected_cowboy_exception) do
NewRelic.log(:debug, "unexpected_cowboy_exception: #{inspect(unexpected_cowboy_exception)}")
{:unexpected_cowboy_exception, []}
end
defp plug_name(conn, match_path) do
"/Plug/#{conn.method}/#{match_path}"
|> String.replace("/*glob", "")
|> String.replace("/*_path", "")
end
end
