sentry

The Official Sentry Client for Elixir which provides a simple API to capture exceptions, automatically handle Plug Exceptions and provides a backend for the Elixir Logger.

Documentation

Installation

To use Sentry with your projects, edit your mix.exs file to add it as a dependency and add the :sentry package to your applications:

defp application do
  [applications: [:sentry, :logger]]
end

defp deps do
  [{:sentry, "~> 6.0.0"}]
end

Capture Exceptions

Sometimes you want to capture specific exceptions. To do so, use Sentry.capture_exception/2.

try do
  ThisWillError.reall()
rescue
  my_exception ->
    Sentry.capture_exception(my_exception, [stacktrace: System.stacktrace(), extra: %{extra: information}])
end

For optional settings check the docs.

Setup with Plug or Phoenix

In your router add the following lines:

use Plug.ErrorHandler
use Sentry.Plug

Capture All Exceptions

This library comes with an extension to capture all error messages that the Plug handler might not. This is based on the Erlang error_logger.

To set this up, add :ok = :error_logger.add_report_handler(Sentry.Logger) to your application's start function. Example:

def start(_type, _opts) do
  children = [
    supervisor(Task.Supervisor, [[name: Sentry.TaskSupervisor]]),
    :hackney_pool.child_spec(Sentry.Client.hackney_pool_name(),  [timeout: Config.hackney_timeout(), max_connections: Config.max_hackney_connections()])
  ]
  opts = [strategy: :one_for_one, name: Sentry.Supervisor]

  :ok = :error_logger.add_report_handler(Sentry.Logger)

  Supervisor.start_link(children, opts)
end

Configuration

Key	Required	Default	Notes
dsn	True	n/a
environment_name	False	:dev
included_environments	False	[:test, :dev, :prod]	If you need non-standard mix env names you need to include it here
tags	False	%{}
release	False	None
server_name	False	None
client	False	Sentry.Client	If you need different functionality for the HTTP client, you can define your own module that implements the Sentry.HTTPClient behaviour and set client to that module
hackney_opts	False	[pool: :sentry_pool]
hackney_pool_max_connections	False	50
hackney_pool_timeout	False	5000
before_send_event	False
after_send_event	False
sample_rate	False	1.0
in_app_module_whitelist	False	[]
report_deps	False	True	Will attempt to load Mix dependencies at compile time to report alongside events
enable_source_code_context	False	False
root_source_code_path	Required if enable_source_code_context is enabled		Should generally be set to File.cwd!
context_lines	False	3
source_code_exclude_patterns	False	[~r"/_build/", ~r"/deps/", ~r"/priv/"]
source_code_path_pattern	False	"**/*.ex"

An example production config might look like this:

config :sentry,
  dsn: "https://public:[email protected]/1",
  environment_name: :prod,
  included_environments: [:prod],
  enable_source_code_context: true,
  root_source_code_path: File.cwd!,
  tags: %{
    env: "production"
  },
  hackney_opts: [pool: :my_pool],
  in_app_module_whitelist: [MyApp]

The environment_name and included_environments work together to determine if and when Sentry should record exceptions. The environment_name is the name of the current environment. In the example above, we have explicitly set the environment to :prod which works well if you are inside an environment specific configuration like config/prod.exs.

Alternatively, you could use Mix.env in your general configuration file:

config :sentry, dsn: "https://public:[email protected]/1",
  included_environments: [:prod],
  environment_name: Mix.env

You can even rely on more custom determinations of the environment name. It's not uncommmon for most applications to have a "staging" environment. In order to handle this without adding an additional Mix environment, you can set an environment variable that determines the release level.

config :sentry, dsn: "https://public:[email protected]/1",
  included_environments: ~w(production staging),
  environment_name: System.get_env("RELEASE_LEVEL") || "development"

In this example, we are getting the environment name from the RELEASE_LEVEL environment variable. If that variable does not exist, we default to "development". Now, on our servers, we can set the environment variable appropriately. On our local development machines, exceptions will never be sent, because the default value is not in the list of included_environments.

Sentry uses the hackney HTTP client for HTTP requests. Sentry starts its own hackney pool named :sentry_pool with a default connection pool of 50, and a connection timeout of 5000 milliseconds. The pool can be configured with the hackney_pool_max_connections and hackney_pool_timeout configuration keys. If you need to set other hackney configurations for things like a proxy, using your own pool or response timeouts, the hackney_opts configuration is passed directly to hackney for each request.

Reporting Exceptions with Source Code

Sentry's server supports showing the source code that caused an error, but depending on deployment, the source code for an application is not guaranteed to be available while it is running. To work around this, the Sentry library reads and stores the source code at compile time. This has some unfortunate implications. If a file is changed, and Sentry is not recompiled, it will still report old source code.

The best way to ensure source code is up to date is to recompile Sentry itself via mix do clean, compile. It's possible to create a Mix Task alias in mix.exs to do this. The example below would allow one to run mix sentry_recompile which will force recompilation of Sentry so it has the newest source and then compile the project:

# mix.exs
defp aliases do
  [sentry_recompile: ["clean", "compile"]]
end

For more documentation, see Sentry.Sources.

Testing Your Configuration

To ensure you've set up your configuration correctly we recommend running the included mix task. It can be tested on different Mix environments and will tell you if it is not currently configured to send events in that environment:

$ MIX_ENV=dev mix sentry.send_test_event
Client configuration:
server: https://sentry.io/
public_key: public
secret_key: secret
included_environments: [:prod]
current environment_name: :dev

:dev is not in [:prod] so no test event will be sent

$ MIX_ENV=prod mix sentry.send_test_event
Client configuration:
server: https://sentry.io/
public_key: public
secret_key: secret
included_environments: [:prod]
current environment_name: :prod

Sending test event!

Docs

To build the docs locally, you'll need the Sphinx:

$ pip install sphinx

Once Sphinx is available building the docs is simply:

$ make docs

You can then view the docs in your browser:

$ open docs/_build/html/index.html

License

This project is Licensed under the MIT License.