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Add http.route attribute and update span name from Plug router #621

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Add http.route attribute and update span name from Plug router #621

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15a197c
Use string span names and update with route from conn.private
lunks Mar 6, 2026
c0df875
Sanitize unknown methods in span name update
lunks Mar 6, 2026
3bf3271
Set http.route attribute and add POST/5xx route tests
lunks Mar 6, 2026
98285ae
Revert changing of atoms to strings
lunks Mar 10, 2026
4420180
Revert mix.lock changes
lunks Mar 10, 2026
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20 changes: 20 additions & 0 deletions instrumentation/opentelemetry_bandit/lib/opentelemetry_bandit.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -468,10 +468,30 @@ defmodule OpentelemetryBandit do
|> Tracer.set_attributes()
end

maybe_update_span_name(conn)
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@yordis yordis Mar 10, 2026

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This couldn't be moved to the start event?

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@lunks lunks Mar 10, 2026

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No. We only have the URL path, not the route name. call_plug! sets it, but the span has already been started:
https://github.com/mtrudel/bandit/blob/1.10.3/lib/bandit/pipeline.ex#L38-L42

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@yordis yordis Mar 10, 2026

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@tsloughter I am gonna defer to you, I am not sure if changing midway the span name is a major concern or not

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@lunks lunks Mar 10, 2026

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If you folks think there's a better approach to accomplish a similar result, let me know.

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@tsloughter-serve tsloughter-serve Apr 28, 2026

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Sorry. This is fine.


Tracer.end_span()
Ctx.clear()
end

defp maybe_update_span_name(conn) do
case conn.private do
%{plug_route: {route, _fun}} ->
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method = sanitize_method(conn.method)
Tracer.update_name("#{method} #{route}")
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Tracer.set_attribute(HTTPAttributes.http_route(), route)

_ ->
:ok
end
end

defp sanitize_method(method) do
if parse_method(method) == HTTPAttributes.http_request_method_values().other,
do: "HTTP",
else: method
end

@doc false
def handle_request_exception(meta, config) do
Tracer.set_status(OpenTelemetry.status(:error, ""))
Expand Down
76 changes: 76 additions & 0 deletions instrumentation/opentelemetry_bandit/test/bandit/opentelemetry_bandit_test.exs
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Original file line number Diff line number Diff line change
Expand Up @@ -488,6 +488,63 @@ defmodule OpentelemetryBanditTest do
assert [] = :otel_events.list(events)
end

test "updates span name and sets http.route from conn.private[:plug_route]" do
OpentelemetryBandit.setup()
port = start_server()

Req.get("http://localhost:#{port}/with_route")

assert_receive {:span,
span(
name: "GET /items/:id",
kind: :server,
attributes: span_attrs
)}

assert Map.get(:otel_attributes.map(span_attrs), HTTPAttributes.http_route()) ==
"/items/:id"
end

test "updates span name with POST method and route" do
OpentelemetryBandit.setup()
port = start_server()

Req.post("http://localhost:#{port}/post_with_route", body: "")

assert_receive {:span,
span(
name: "POST /items",
kind: :server,
attributes: span_attrs
)}

attrs = :otel_attributes.map(span_attrs)
assert Map.get(attrs, HTTPAttributes.http_route()) == "/items"
assert Map.get(attrs, HTTPAttributes.http_response_status_code()) == 201
end

test "updates span name with route on 5xx response" do
OpentelemetryBandit.setup()
port = start_server()

Req.get("http://localhost:#{port}/error_with_route", retry: false)

expected_status = OpenTelemetry.status(:error, "")

assert_receive {:span,
span(
name: "GET /items/:id",
kind: :server,
attributes: span_attrs,
status: ^expected_status
)}

attrs = :otel_attributes.map(span_attrs)
assert Map.get(attrs, HTTPAttributes.http_route()) == "/items/:id"
assert Map.get(attrs, HTTPAttributes.http_response_status_code()) == 500
assert Map.get(attrs, ErrorAttributes.error_type()) == "500"
end

test "with halted request" do
OpentelemetryBandit.setup()
port = start_server()
Expand Down Expand Up @@ -522,6 +579,25 @@ defmodule OpentelemetryBanditTest do
conn |> send_resp(200, "OK")
end

def with_route(conn) do
conn
|> put_private(:plug_route, {"/items/:id", fn -> nil end})
|> send_resp(200, "OK")
end

def post_with_route(conn) do
conn
|> put_private(:plug_route, {"/items", fn -> nil end})
|> send_resp(201, "Created")
end

def error_with_route(conn) do
conn
|> put_private(:plug_route, {"/items/:id", fn -> nil end})
|> send_resp(500, "Internal Server Error")
|> halt()
end

def with_body(conn) do
conn
|> put_resp_content_type("application/json")
Expand Down