Clarify the Logging situation

[PJUllrich]

Problem Statement

Hey folks, now with the new TelemetryProcessor in place, I'm a bit confused as to whether we still need to add the :logger.add_handler/3 in the application. In the auto-setup for logs PR #998, you mention that manually adding the logger is no longer necessary but the docs don't clarify that yet.

I ran into this confusion because I've added new metadata to my log events and they show in my logs, but they don't show up in the Sentry logs UI (Discover > Logs > Click on a log row). Here's my setup:

I've recently upgraded to the latest 12.0.3 version and added the enable_logs: true flag and telemetry_processor_categories: [:log, :error, :check_in, :transaction] as described in the Changelog. I left my :logger.add_handler/3 in my application.ex because the Changelog did not specify that it needs removing. My Logger.error("foobar") calls still got logged in Sentry so all was well.

Now, I've added new metadata to my log events and they show up when I view my logs on my server, but they don't show in the Sentry Logs UI. I haven't had an error after making this change, so I can't tell whether the new metadata shows up in the regular Sentry error events.

In my application.ex, I have now:

def start(_type, _args) do
    :logger.add_handler(:sentry_error_log_handler, Sentry.LoggerHandler, %{
      config: %{metadata: :all, capture_log_messages: true, level: :error}
    })
   # ...
end

# config/prod.exs

config :sentry,
  dsn: "my-dsn",
  environment_name: Mix.env(),
  enable_source_code_context: true,
  root_source_code_paths: [File.cwd!()],
  enable_logs: true,
  telemetry_processor_categories: [:log, :error, :check_in, :transaction],
  integrations: [
    telemetry: [
      report_handler_failures: true
    ],
    oban: [
      capture_errors: true,
      cron: [enabled: true]
    ]
  ]

So, my questions are:

1. Do we still need to add :logger.add_handler/3 if we add enable_logs: true to our Sentry config?
2. If not, how do we configure the logs (e.g. level, metadata, capture_log_messages: true) and are the configuration options the same as for the Sentry.LoggerHandler?
3. How can we still create Sentry Error events for Logger.error/1 calls but not for Logger.info/1 calls?

Solution Brainstorm

No response

[linear-code]

ELIXIR-57

[solnic]

Peter! My friend, thank you for bringing this up. Long-story short: you can consider Sentry.LoggerBackend as soon-to-be-deprecated. We're going to move fully to the new Sentry.LoggerHandler.* modules for both structured logging and capturing error logs and crashes from Logger to report them to Sentry as errors/messages (like the Sentry.LoggerBackend does already).

To answer your specific questions:

Do we still need to add :logger.add_handler/3 if we add enable_logs: true to our Sentry config?

No, you don't. The handler is added automatically when enable_logs is set to true, but there's a caveat...see last reply below :/

If not, how do we configure the logs (e.g. level, metadata, capture_log_messages: true) and are the configuration options the same as for the Sentry.LoggerHandler?

Under config :sentry, :logs, ... and yes, they are the same except capture_log_messages because it's a feature from Sentry.LoggerHandler.ErrorBackend.

How can we still create Sentry Error events for Logger.error/1 calls but not for Logger.info/1 calls?

So, unfortunately for this you have to add the handler manually and pass your custom config. This is something I'm gonna improve in 13.0.1.

[PJUllrich]

@solnic thank you, Peter! Sorry for the late reply. I've been attending and then recovering from ElixirConf EU :P

So, given that I need to capture Logger.error/1 calls, I could remove the enable_logs: true from my prod.exs and just keep the Sentry.LoggerHandler in my application.ex, correct?