Note: Support for custom namespaces was added in version 1.3.0 of the AppSignal for Elixir package.
The AppSignal for Elixir package integrates with Plug. To set up the integration, please follow our installation guide.
This page describes how to set up AppSignal in a Plug application, and how to add instrumentation for events within requests. For more information about custom instrumentation, read the Elixir instrumentation documentation.
More information can be found in the AppSignal Hex package documentation.
We'll start out with a small Plug app that accepts
GET requests to
returns a welcome message. To start logging HTTP requests in this app, we'll
1 2 3 4 5 6 7 8 9 10 11 defmodule AppsignalPlugExample do use Plug.Router use Appsignal.Plug # <- Add this plug :match plug :dispatch get "/" do send_resp(conn, 200, "Welcome") end end
This will create a transaction for every HTTP request which is performed on the endpoint.
Appsignal.Plug will start transactions for you, it won't instrument
events in your app just yet. To do that, we need to add some custom
This example app looks like the one we used before, but it has a slow function
slow/0) we'd like to add instrumentation for. To do that, we need
to use the
Appsignal.instrument/2-3 helper in our called function:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 defmodule AppsignalPlugExample do use Plug.Router plug :match plug :dispatch get "/" do slow() send_resp(conn, 200, "Welcome") end defp slow do Appsignal.instrument("slow", fn -> :timer.sleep(1000) end) end use Appsignal.Plug end
This will add an event for the
slow/0 function to the current transaction
whenever it's called. For more information about custom instrumentation, read
the Elixir instrumentation documentation.
Exceptions in included Plugs are automatically caught by AppSignal, but performance samples need to be set up manually using the custom instrumentation helpers or decorators.
To add instrumentation to Plugs, use the
1 2 3 4 5 6 7 8 9 10 11 12 defmodule SlowPlugWithDecorators do import Plug.Conn def init(opts), do: opts def call(conn, _) do Appsignal.instrument("SlowPlugWithDecorators", fn -> :timer.sleep(1000) conn end) end end