Honeybadger for Elixir

Elixir Plug, Logger and client for the ⚡ Honeybadger error notifier.

Upgrading to v0.11? See the release notes

Getting Started

Watch our screencast by Josh Adams of ElixirSips!

Version Requirements

• Erlang >= 18.0
• Elixir >= 1.10
• Plug >= 1.0
• Phoenix >= 1.0 (This is an optional dependency and the version requirement applies only if you are using Phoenix)

1. Install the package

Add the Honeybadger package to deps/0 in your application's mix.exs file and run mix do deps.get, deps.compile

defp deps do
  [{:honeybadger, "~> 0.16"}]
end

2. Set your API key and environment name

By default the environment variable HONEYBADGER_API_KEY will be used to find your API key to the Honeybadger API. If you would like to specify your key or any other configuration options a different way, you can do so in config.exs:

config :honeybadger,
  api_key: "{{PROJECT_API_KEY}}"

We also need to set the name of the environment for each environment. This ensures that we can accurately report the environment that an error occurs in. You can add something like the following to each of your #{env}.exs files:

config :honeybadger,
  environment_name: :dev

If environment_name is not set we will fall back to the value of Mix.env(). Mix.env() uses the atomized value of the MIX_ENV environment variable and defaults to :prod when the environment variable is not set. This should be good for most setups. If you want to have an environment_name which is different than the Mix.env(), you should set environment_name in your config.exs files for each environment. This ensures that we can give you accurate environment information even during compile time. Explicitly setting the environment_name config takes higher precedence over the Mix.env() value.

3. Enable error reporting

The Honeybadger package can be used as a Plug alongside your Phoenix applications, as a logger backend, or as a standalone client for sprinkling in exception notifications where they are needed.

Phoenix and Plug

The Honeybadger Plug adds a Plug.ErrorHandler to your pipeline. Simply use the Honeybadger.Plug module inside of a Plug or Phoenix.Router and any crashes will be automatically reported to Honeybadger. It's best to use Honeybadger.Plug after the Router plugs so that exceptions due to non-matching routes are not reported to Honeybadger.

Phoenix app

defmodule MyPhoenixApp.Router do
  use Crywolf.Web, :router
  use Honeybadger.Plug

  pipeline :browser do
    [...]
  end
end

Plug app

defmodule MyPlugApp do
  use Plug.Router
  use Honeybadger.Plug

  [... the rest of your plug ...]
end

Logger

Just set the use_logger option to true in your application's config.exs and you're good to go! Any SASL compliant processes that crash will send an error report to the Honeybadger.Logger. After the error reaches the logger we take care of notifying Honeybadger for you!

Manual reporting

You can manually report rescued exceptions with the Honeybadger.notify function.

try do
  File.read! "this_file_really_should_exist_dang_it.txt"
rescue
  exception ->
    Honeybadger.notify(exception, metadata: %{}, stacktrace: __STACKTRACE__, fingerprint: "")
end

Breadcrumbs

Breadcrumbs allow you to record events along a processes execution path. If an error is thrown, the set of breadcrumb events will be sent along with the notice. These breadcrumbs can contain useful hints while debugging.

Breadcrumbs are stored in the logger context, referenced by the calling process. If you are sending messages between processes, breadcrumbs will not transfer automatically. Since a typical system might have many processes, it is advised that you be conservative when storing breadcrumbs as each breadcrumb consumes memory.

Automatic Breadcrumbs

We leverage the telemetry library to automatically create breadcrumbs from specific events.

Phoenix

If you are using phoenix (>= v1.4.7) we add a breadcrumb from the router start event.

Ecto

We can create breadcrumbs from Ecto SQL calls if you are using ecto_sql (>= v3.1.0). You also must specify in the config which ecto adapters you want to be instrumented:

config :honeybadger,
  ecto_repos: [MyApp.Repo]

Sample Application

If you'd like to see the module in action before you integrate it with your apps, check out our sample Phoenix application.

You can deploy the sample app to your Heroku account by clicking this button:

Don't forget to destroy the Heroku app after you're done so that you aren't charged for usage.

The code for the sample app is available on Github, in case you'd like to read through it, or run it locally.

Filtering Sensitive Data

Before data is sent to Honeybadger, it is passed through a filter to remove sensitive fields and do other processing on the data. The default configuration is equivalent to:

config :honeybadger,
  filter: Honeybadger.Filter.Default,
  filter_keys: [:password, :credit_card]

This will remove any entries in the context, session, cgi_data and params that match one of the filter keys. The filter is case insensitive and matches atoms or strings.

If Honeybadger.Filter.Default does not suit your needs, you can implement your own filter. See the Honeybadger.Filter.Mixin module doc for details on implementing your own filter.

Filtering Arguments

Honeybadger can show arguments in the stacktrace for FunctionClauseError exceptions. To enable argument reporting, set filter_args to false:

config :honeybadger, filter_args: false

Excluding Errors

By default Honeybadger will be notified when an error occurs. To override this configuration in order not to send out errors to Honeybadger, set exclude_errors option in config/config.exs.

This can be done by passing a list of errors to be excluded:

config :honeybadger,
  exclude_errors: ["RuntimeError"]

or

config :honeybadger,
  exclude_errors: [RuntimeError]

Also you can implement the Honeybadger.ExcludeErrors behaviour function exclude_error?/1, which receives the full Honeybadger.Notice and returns a boolean signalling the error exclusion or not.

  defmodule ExcludeFunClauseErrors do
    alias Honeybadger.ExcludeErrors

    @behaviour ExcludeErrors

    @impl ExcludeErrors

    def exclude_error?(notice) do
      notice.error.class == "FunctionClauseError"
    end
  end

config :honeybadger,
  exclude_errors: ExcludeFunClauseErrors

Customizing Error Grouping

See the Error Monitoring Guide for more information about how honeybadger groups similar exception together. You can customize the grouping for each exception in Elixir by sending a custom fingerprint when the exception is reported.

To customize the fingerprint for all exceptions that are reported from your app, use the fingerprint_adapter configuration option in config.ex:

config :honeybadger, fingerprint_adapter: MyApp.CustomFingerprint

 defmodule MyApp.CustomFingerprint do
  @behaviour Honeybadger.FingerprintAdapter

  def parse(notice) do
    notice.notifier.language <> "-" <> notice.notifier.name
  end
end

You can also customize the fingerprint for individual exceptions when calling Honeybadger.notify:

Honeybadger.notify(%RuntimeError{}, fingerprint: "culprit_id-123")

Advanced Configuration

You can set configuration options in config.exs. It looks like this:

config :honeybadger,
  api_key: "{{PROJECT_API_KEY}}",
  environment_name: :prod

If you'd rather read, eg., environment_name from the OS environment, you can do like this:

config :honeybadger,
  environment_name: {:system, "HONEYBADGER_ENV"},
  revision: {:system, "HEROKU_SLUG_COMMIT"}

NOTE: This works only for the string options, and environment_name.

Here are all of the options you can pass in the keyword list:

Name	Description	Default
app	Name of your app's OTP Application as an atom	Mix.Project.config[:app]
api_key	Your application's Honeybadger API key	System.get_env("HONEYBADGER_API_KEY"))
environment_name	(required) The name of the environment your app is running in.	:prod
exclude_errors	Filters out errors from being sent to Honeybadger	[]
exclude_envs	Environments that you want to disable Honeybadger notifications	[:dev, :test]
hostname	Hostname of the system your application is running on	:inet.gethostname
origin	URL for the Honeybadger API	"https://api.honeybadger.io"
project_root	Directory root for where your application is running	System.cwd/0
revision	The project's git revision	nil
filter	Module implementing Honeybadger.Filter to filter data before sending to Honeybadger.io	Honeybadger.Filter.Default
filter_keys	A list of keywords (atoms) to filter. Only valid if filter is Honeybadger.Filter.Default	[:password, :credit_card]
filter_args	If true, will remove function arguments in backtraces	true
filter_disable_url	If true, will remove the request url	false
filter_disable_session	If true, will remove the request session	false
filter_disable_params	If true, will remove the request params	false
fingerprint_adapter	Implementation of FingerprintAdapter behaviour
notice_filter	Module implementing Honeybadger.NoticeFilter. If nil, no filtering is done.	Honeybadger.NoticeFilter.Default
sasl_logging_only	If true, will notifiy for SASL errors but not Logger calls	true
use_logger	Enable the Honeybadger Logger for handling errors outside of web requests	true
ignored_domains	Add domains to ignore Error events in Honeybadger.Logger.	[:cowboy]
breadcrumbs_enabled	Enable breadcrumb event tracking	false
ecto_repos	Modules with implemented Ecto.Repo behaviour for tracking SQL breadcrumb events	[]

Public Interface

Honeybadger.notify: Send an exception to Honeybadger.

Use the Honeybadger.notify/2 function to send exception information to the collector API. The first parameter is the exception and the second parameter is the context/metadata/fingerprint. There is also a Honeybadger.notify/1 which doesn't require the second parameter.

Examples:

try do
  File.read! "this_file_really_should_exist_dang_it.txt"
rescue
  exception ->
    context = %{user_id: 5, account_name: "Foo"}
    Honeybadger.notify(exception, metadata: context, stacktrace: __STACKTRACE__)
end

---

Honeybadger.context/1: Set metadata to be sent if an error occurs

Honeybadger.context/1 is provided for adding extra data to the notification that gets sent to Honeybadger. You can make use of this in places such as a Plug in your Phoenix Router or Controller to ensure useful debugging data is sent along.

Examples:

def MyPhoenixApp.Controller
  use MyPhoenixApp.Web, :controller

  plug :set_honeybadger_context

  def set_honeybadger_context(conn, _opts) do
    user = get_user(conn)
    Honeybadger.context(user_id: user.id, account: user.account.name)
    conn
  end
end

Honeybadger.context/1 stores the context data in the process dictionary, so it will be sent with errors/notifications on the same process. The following Honeybadger.notify/1 call will not see the context data set in the previous line.

Honeybadger.context(user_id: 5)
Task.start(fn ->
  # this notify does not see the context set earlier
  # as this runs in a different elixir/erlang process.
  Honeybadger.notify(%RuntimeError{message: "critical error"})
end)

---

Honeybadger.add_breadcrumb/2: Store breadcrumb within process

Appends a breadcrumb to the notice. Use this when you want to add some custom data to your breadcrumb trace in effort to help debugging. If a notice is reported to Honeybadger, all breadcrumbs within the execution path will be appended to the notice. You will be able to view the breadcrumb trace in the Honeybadger interface to see what events led up to the notice.

Examples:

Honeybadger.add_breadcrumb("Email sent", metadata: %{
  user: user.id,
  message: message
})

---

Proxy configuration

If your server needs a proxy to access Honeybadger, add the following to your config

config :honeybadger,
  proxy: "url",
  proxy_auth: {"username", "password"}

Excluded environments

Honeybadger won't report errors from :dev and :test environments by default. To enable error reporting in dev:

1. Set the HONEYBADGER_API_KEY as documented above
2. Remove :dev from the exclude_envs by adding this to your config/dev.exs

config :honeybadger,
  exclude_envs: [:test]

3. Run the mix honeybadger.test mix task task to simulate an error

Changelog

See https://github.com/honeybadger-io/honeybadger-elixir/blob/master/CHANGELOG.md

Contributing

If you're adding a new feature, please submit an issue as a preliminary step; that way you can be (moderately) sure that your pull request will be accepted.

To contribute your code:

1. Fork it.
2. Create a topic branch git checkout -b my_branch
3. Commit your changes git commit -am "Boom"
4. Push to your branch git push origin my_branch
5. Send a pull request

Publishing a release on hex.pm

Github Workflow

A new version can be published on Hex.pm using the Publish New Release workflow. The workflow can be triggered manually from the Github Actions page and takes the following input:

• version: One of patch, minor or major. The version number will be bumped accordingly.
• changes: An entry to be added to the changelog.

Manual Release

Versioning, changelog generation and publishing to hex.pm is handled by the mix expublish task. You can read more about it here.

1. mix deps.get
2. echo "CHANGELOG ENTRY" > RELEASE.MD
3. mix expublish.[patch|minor|major]

License

This library is MIT licensed. See the LICENSE file in this repository for details.