Remove bandit from default excluded domains and recommend PlugCapture only for Cowboy (#900)

Co-authored-by: Andrea Leopardi <an.leopardi@gmail.com>

Author: martosaur

lib/sentry/logger_backend.ex

@@ -33,7 +33,7 @@ defmodule Sentry.LoggerBackend do
   ## Configuration
 
   * `:excluded_domains` - Any messages with a domain in the configured
-  list will not be sent. Defaults to `[:cowboy, :bandit]` to avoid double reporting
+  list will not be sent. Defaults to `[:cowboy]` to avoid double reporting
   events from `Sentry.PlugCapture`.
 
   * `:metadata` - To include non-Sentry Logger metadata in reports, the
@@ -72,7 +72,7 @@ defmodule Sentry.LoggerBackend do
 
   defstruct level: :error,
             metadata: [],
-            excluded_domains: [:cowboy, :bandit],
+            excluded_domains: [:cowboy],
             capture_log_messages: false
 
   ## Callbacks

lib/sentry/logger_handler.ex

@@ -26,7 +26,7 @@ defmodule Sentry.LoggerHandler do
     ],
     excluded_domains: [
       type: {:list, :atom},
-      default: [:cowboy, :bandit],
+      default: [:cowboy],
       type_doc: "list of `t:atom/0`",
       doc: """
       Any messages with a domain in the configured list will not be sent. The default is so as

lib/sentry/plug_capture.ex

@@ -1,11 +1,17 @@
 defmodule Sentry.PlugCapture do
   @moduledoc """
-  Provides basic functionality to capture and send errors occurring within
-  Plug applications, including Phoenix.
+  Ensures proper error reporting for Plug applications that use Cowboy.
 
   It is intended for usage with `Sentry.PlugContext`, which adds relevant request
   metadata to the Sentry context before errors are captured.
 
+  > #### Only for Cowboy {: .info}
+  >
+  > `Sentry.PlugCapture` is only recommended for Cowboy applications.
+  > For applications running on Bandit, which is the most recent default webserver
+  > in Phoenix, `Sentry.PlugContext` should be enough, and using `Sentry.PlugCapture`
+  > might result in duplicate errors.
+
   ## Usage
 
   ### With Phoenix
@@ -69,7 +75,6 @@ defmodule Sentry.PlugCapture do
       * scrubs sensitive body params just like `Sentry.PlugContext.default_body_scrubber/1`
 
   """
-
   defmacro __using__(opts) do
     quote do
       opts = unquote(opts)

lib/sentry/plug_context.ex

@@ -12,9 +12,9 @@ defmodule Sentry.PlugContext do
 
       plug Sentry.PlugContext
 
-  However, this module is generally intended to be used with `Sentry.PlugCapture`:
-  this plug will add context metadata to the request, while `Sentry.PlugCapture` will
-  capture raised exceptions and errors and report them to Sentry with the added metadata.
+  This plug will add context metadata to the request, which will be added to
+  reported errors that happen during plug execution. For Cowboy
+  applications, you will also need to use `Sentry.PlugCapture`.
 
   ### Scrubbing `POST` Body Params
 

pages/setup-with-plug-and-phoenix.md

@@ -1,17 +1,15 @@
 # Setup with Plug and Phoenix
 
-You can capture errors in Plug (and Phoenix) applications with `Sentry.PlugContext` and `Sentry.PlugCapture`. `Sentry.PlugContext` adds contextual metadata from the current request which is then included in errors that are captured and reported by `Sentry.PlugCapture`.
+You can enrich errors in Plug (and Phoenix) applications with `Sentry.PlugContext`. `Sentry.PlugContext` adds contextual metadata from the current request which is then included in errors.
 
 ## For Phoenix Applications
 
 If you are using Phoenix:
 
-  1. Add `Sentry.PlugCapture` above the `use Phoenix.Endpoint` line in your endpoint file
   1. Add `Sentry.PlugContext` below `Plug.Parsers`
 
 ```diff
  defmodule MyAppWeb.Endpoint
-+  use Sentry.PlugCapture
    use Phoenix.Endpoint, otp_app: :my_app
 
    # ...
@@ -24,6 +22,16 @@ If you are using Phoenix:
 +  plug Sentry.PlugContext
 ```
 
+  1. If you're using Cowboy, also add `Sentry.PlugCapture` above the `use Phoenix.Endpoint` line in your endpoint file
+  
+```diff
+ defmodule MyAppWeb.Endpoint
++  use Sentry.PlugCapture
+   use Phoenix.Endpoint, otp_app: :my_app
+
+   # ...
+```
+
 If you're also using [Phoenix LiveView](https://github.com/phoenixframework/phoenix_live_view), consider also setting up your LiveViews to use the `Sentry.LiveViewHook` hook:
 
 ```elixir
@@ -72,13 +80,11 @@ end
 
 If you are in a non-Phoenix Plug application:
 
-  1. Add `Sentry.PlugCapture` at the top of your Plug application
   1. Add `Sentry.PlugContext` below `Plug.Parsers` (if it is in your stack)
 
 ```diff
  defmodule MyApp.Router do
    use Plug.Router
-+  use Sentry.PlugCapture
 
    # ...
 
@@ -87,3 +93,13 @@ If you are in a non-Phoenix Plug application:
 
 +  plug Sentry.PlugContext
 ```
+
+  1. If you're using Cowboy, add `Sentry.PlugCapture` at the top of your Plug application
+
+```diff
+ defmodule MyApp.Router do
+   use Plug.Router
++  use Sentry.PlugCapture
+
+   # ...
+```

test/logger_backend_test.exs

@@ -143,7 +143,7 @@ defmodule Sentry.LoggerBackendTest do
     Logger.configure_backend(Sentry.LoggerBackend, excluded_domains: [:cowboy, :bandit])
   end
 
-  test "sends two errors when a Plug process crashes if bandit domain is not excluded" do
+  test "sends two errors when a Plug process crashes if PlugCapture is used and :bandit not excluded" do
     Logger.configure_backend(Sentry.LoggerBackend, excluded_domains: [])
 
     ref = register_before_send()

test/sentry/logger_handler_test.exs

@@ -110,7 +110,7 @@ defmodule Sentry.LoggerHandlerTest do
     end
 
     @tag handler_config: %{excluded_domains: []}
-    test "sends two errors when a Plug process crashes if bandit domain is not excluded",
+    test "sends two errors when a Plug process crashes if PlugCapture is used and :bandit not excluded",
          %{sender_ref: ref} do
       start_supervised!({Sentry.ExamplePlugApplication, server: :bandit}, restart: :temporary)