Adding context to errors

Honeybadger can display additional custom key/value metadata — or “context” — with each error report. Context is what you’re looking for if:

• You want to record the current user’s id or email address at the time of an exception
• You need to send raw POST data for use in debugging
• You have any other metadata you’d like to send with an exception

There are two ways to add context to errors in your code: global and local. While you can add any key/value data to context, a few keys have a special meaning in Honeybadger.

Global context

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.

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)

Local context

You can also add context to a manual error report using the metadata option, like this:

context = %{user_id: 5, account_name: "Foo"}
Honeybadger.notify(exception, metadata: context, stacktrace: __STACKTRACE__)

Local context always overrides any global values when the error is reported.

Special context keys

While you can add any key/value data to context, a few keys have special meaning in Honeybadger:

Option	Description
user_id	The String user ID used by Honeybadger to aggregate user data across occurrences on the error page.
user_email	Same as user_id, but for email addresses

Limits

Honeybadger uses the following limits to ensure the service operates smoothly for everyone:

• Nested objects have a max depth of 20
• Context values have a max size of 64Kb

When an error notification includes context data that exceed these limits, the context data will be truncated, and the notification will still be processed.