Add timezone support for Oban cron monitoring

[Flo0807]

Sentry supports monitoring scheduled Oban jobs. I wanted to use this feature in my application to monitor Oban cron jobs, but Sentry always threw A missed check-in was detected errors. I looked into the problem and noticed in the web interface that the configured timezone for all cron monitors was set to UTC while I configured the Oban cron jobs to use the Europe/Berlin timezone. Therefore, I needed to change the timezone of the created cron monitors to Europe/Berlin manually to be in sync with my jobs.

I figured out that you can set the timezone with a Manual Setup, but I'd like to have a timezone setting for my config that allows me to set the timezone for the oban cron integrations. I would rather not do a manual setup only to set the timezone value.

This is my setup:

# config/config.exs
config :sentry,
  ...,
  integrations: [
    oban: [
      cron: [enabled: true],
      capture_errors: true
    ]
  ]

# config/config.exs
config :my_app, Oban,
  repo: MyApp.Repo,
  queues: [default: 10],
  plugins: [
    {Oban.Plugins.Pruner, max_age: :timer.hours(24) * 90},
    {Oban.Plugins.Lifeline, rescue_after: :timer.minutes(5)},
    {Oban.Plugins.Cron,
     crontab: [
       {"0 8 * * 1", MyApp.Workers.ExampleWorker}
     ],
     timezone: "Europe/Berlin"}
  ]

[whatyouhide]

@savhappy @solnic I think it's time we consider a per-job configuration when necessary.

One option is to do it via a behaviour that jobs (not just Oban jobs) can implement. The behaviour can be Sentry.CheckIn too.

defmodule Sentry.CheckIn do
  @callback sentry_check_in_configuration() :: (options_to_merge :: keyword())

  # ...
end

Then, an Oban worker could implement it like this:

defmodule MyApp.Worker do
  use Oban.Worker
 
  @behaviour Sentry.CheckIn

  @impl Oban.Worker
  def process(...)

  @impl Sentry.CheckIn
  def sentry_check_in_configuration do
    [timezone: "Europe/Berlin"]
  end
end

Then, integrations like the Oban one can essentially do:

config =
  if function_exported?(job.module, :sentry_check_in_configuration, 0) do
    Keyword.merge(config, job.module.sentry_check_in_configuration())
  else
    config
  end

This is a basic approach, but I think it works and it's going to scale out pretty well. The callback could also take an argument that is decided by the integration itself, like

@callbac sentry_check_in_configuration(info :: term()) :: keyword()

In Oban's case, it would be the Oban.Job.

Thoughts?

[solnic]

@savhappy @solnic I think it's time we consider a per-job configuration when necessary.

I can see this being useful (in general, not just for setting TZ for cron check-ins) but I'm wondering if this means you don't think that a top-level default for TZ that we could set via config would be a good idea? We could just have this:

config :sentry,
  # ...,
  integrations: [
    oban: [
      cron: [enabled: true, time_zone: "Europe/Berlin"],
      capture_errors: true
    ]
  ]

...and that could be overridden by a job's custom check-in config, what do you think? From what I see in the code, it seems doable, since we have Sentry.Integrations.Oban.Cron.job_to_check_in_opts that receives an Oban job, config (which is cron[:oban][:cron]) and then it also has access to Sentry.Config.integrations()[:monitor_config_defaults].

[whatyouhide]

It's doable but I would prioritize it lower than a per-job config (see also #829 which would be solved by the per-job config).

[savhappy]

This seems like a good use for a behaviour like @whatyouhide mentioned so we don't have to make additional considerations later. I can change the in-progress #829 to handle the new implementation. Or should we separate it?

[whatyouhide]

@savhappy I'd make a new PR with this change and then refactor #829 as needed.