# BoomNotifier
[](https://hex.pm/packages/boom_notifier)
[](https://github.com/wyeworks/boom/actions/workflows/elixir.yml)
---
This package allows your Phoenix application to send notifications whenever
an exceptions is raised. By default it includes an email and a webhook
notifier, but you can implement your custom ones.
It was inspired by the [ExceptionNotification](https://github.com/smartinez87/exception_notification)
gem that provides a similar functionality for Rack/Rails applications.
You can read the full documentation at [https://hexdocs.pm/boom_notifier](https://hexdocs.pm/boom_notifier).
## Installation
The package can be installed by adding `boom_notifier` to your list of dependencies in
`mix.exs`:
```elixir
def deps do
[
{:boom_notifier, "~> 0.4.1"}
]
end
```
## How to use it
### Webkook notifier
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
notifier: BoomNotifier.WebhookNotifier,
options: [
url: "http://example.com"
]
# ...
```
To configure it, you need to set the `url` in the `options` keyword list. A `POST` request with a `json` will be made to that webhook when an error ocurrs with the relevant information.
### Email notifier
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
notifier: BoomNotifier.MailNotifier,
options: [
mailer: YourApp.Mailer,
from: "me@example.com",
to: "foo@example.com",
subject: "BOOM error caught"
]
# ...
```
For the email to be sent, you need to define a valid mailer in the `options` keyword list. You can customize the `from`, `to` and `subject` attributes.
## Custom notifiers
To create a custom notifier, you need to implement the `BoomNotifier.Notifier` behaviour:
```elixir
@callback notify(list(%ErrorInfo{}), keyword(String.t())) :: no_return()
```
```elixir
defmodule CustomNotifier do
@behaviour BoomNotifier.Notifier
@impl BoomNotifier.Notifier
def notify(errors, options) do
# ...
# ...
# ...
end
```
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
notifier: CustomNotifier,
options: [
# ...
]
```
You can also implement an optional callback `validate_config` that receives
the `options` keyword list set in the notifier so the user can be warned
during compilation if the attributes are not correct.
```elixir
@callback validate_config(keyword(String.t())) :: :ok | {:error, String.t()}
```
## Multiple notifiers
BoomNotifier also supports a list of multiple notifiers like in the example below:
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
notifiers: [
[
notifier: BoomNotifier.WebhookNotifier,
options: [
url: "http://example.com",
]
],
[
notifier: CustomNotifier,
options: # ...
]
]
```
## Notification Trigger
By default, `BoomNotifier` will send a notification every time an exception is
raised.
However, there are different strategies to decide when to send the
notifications using the `:notification_trigger` option with one of the
following values: `:always` and `:exponential`.
### Always
This option is the default one. It will trigger a notification for every
exception.
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
notification_trigger: :always,
notifiers: [
# ...
]
```
### Exponential
It uses a formula of `log2(errors_count)` to determine whether to send a
notification, based on the accumulated error count for each specific
exception. This makes the notifier only send a notification when the count
is: 1, 2, 4, 8, 16, 32, 64, 128, ..., (2**n).
You can also set an optional max value.
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
notification_trigger: :exponential,
notifiers: [
# ...
]
```
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
notification_trigger: [exponential: [limit: 100]]
notifiers: [
# ...
]
```
## Custom data or Metadata
By default, `BoomNotifier` will **not** include any custom data from your
requests.
However, there are different strategies to decide which information do
you want to include in the notifications using the `:custom_data` option
with one of the following values: `:assigns`, `:logger` or both.
The included information will show up in your notification, in a new section
titled "Metadata".
### Assigns
This option will include the data that is in the [connection](https://hexdocs.pm/plug/Plug.Conn.html)
`assigns` field.
You can also specify the fields you want to retrieve from `conn.assigns`.
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
custom_data: :assigns,
notifiers: [
# ...
]
```
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
custom_data: [assigns: [fields: [:current_user, :session_data]]],
notifiers: [
# ...
]
```
Example of adding custom data to the connection:
```elixir
assign(conn, :name, "John")
```
### Logger
This option will include the data that is in the [Logger](https://hexdocs.pm/logger/Logger.html)
`metadata` field.
You can also specify the fields you want to retrieve from `Logger.metadata()`.
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
custom_data: :logger,
notifiers: [
# ...
]
```
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
custom_data: [logger: [fields: [:request_id, :current_user]]],
notifiers: [
# ...
]
```
Example of adding custom data to the logger:
```elixir
Logger.metadata(name: "John")
```
### Using both
You can do any combination of the above settings to include data
from both sources. The names of the fields are independent for each
source, they will appear under the source namespace.
```elixir
defmodule YourApp.Router do
use Phoenix.Router
use BoomNotifier,
custom_data: [
[assigns: [fields: [:current_user]]],
[logger: [fields: [:request_id, :current_user]]]
],
notifiers: [
# ...
]
```
## License
BoomNotifier is released under the terms of the [MIT License](https://github.com/wyeworks/boom/blob/master/LICENSE).
## Credits
The authors of this project are [Ignacio](https://github.com/iaguirre88) and [Jorge](https://github.com/jmbejar). It is sponsored and maintained by [Wyeworks](https://www.wyeworks.com).
