Plug actions registered as "unknown"

Affected components

  • AppSignal Elixir package versions: from v1.5.0-beta.1 - v1.13.x


AppSignal groups performance and error samples by "action name". In Phoenix, we use the controller and action name (like AppsignalPhoenixExampleWeb.UserController#show). In pure Plug apps, it'd be best to fall back on the route name (like /users/:id), like we do for Sinatra apps in Ruby, but we can't currently get that data out of the Plug.Conn.

In versions before version 1.5.0-beta.1, Appsignal.Plug used the request method and the request path as the action name in plug-only apps. This caused problems for apps with unique URLs, as it creates a separate performance/error incident for each variation of the URL. To fix this, we're using "unknown" as the default action name in Plug apps, and we're allowing users to override that.


To override the "unknown" action name, use Appsignal.Transaction.set_action/1 from anywhere within the action.

get "/users/:id" do
  Appsignal.Transaction.set_action("GET /users/:id")
  send_resp(conn, 200, "Welcome")

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