feat: distributed scheduling for version check job (#13042)

This change spreads Chatwoot Hub version checks across the day by
scheduling each installation at a stable minute derived from its
installation identifier, instead of having all instances check at the
same fixed time.

Closes
-
https://linear.app/chatwoot/issue/CW-6107/handle-the-spike-at-12-utc-on-chatwoot-hub

What changed
- Added `Internal::TriggerDailyScheduledItemsJob` to act as the daily
trigger for deferred internal jobs.
- Updated the version check cron entry to run once daily at `00:00 UTC`
and enqueue the actual version check for that installation’s assigned
minute of the day.
- Used a deterministic minute-of-day derived from
`ChatwootHub.installation_identifier` so the check time stays stable
across deploys and restarts.
- Kept the existing cron schedule key while switching it to the new
orchestrator job.

How to test
- Run `bundle exec rspec
spec/jobs/internal/check_new_versions_job_spec.rb
spec/jobs/internal/trigger_daily_scheduled_items_job_spec.rb
spec/configs/schedule_spec.rb`
- In a Rails console, run
`Internal::TriggerDailyScheduledItemsJob.perform_now` and verify
`Internal::CheckNewVersionsJob` is enqueued with a `wait_until` later
the same UTC day.
- In Super Admin settings, use Refresh and verify the version check
still runs immediately.

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

app/jobs/internal/trigger_daily_scheduled_items_job.rb

@@ -0,0 +1,25 @@
+class Internal::TriggerDailyScheduledItemsJob < ApplicationJob
+  queue_as :scheduled_jobs
+
+  def perform
+    # Schedule daily deferred jobs here so each installation can spread load
+    # across the day without changing its slot on deploys or restarts.
+    schedule_version_check
+  end
+
+  private
+
+  def schedule_version_check
+    return unless Rails.env.production?
+
+    Internal::CheckNewVersionsJob.set(wait_until: version_check_run_at).perform_later
+  end
+
+  def version_check_run_at
+    Time.current.utc.beginning_of_day + designated_minute.minutes
+  end
+
+  def designated_minute
+    @designated_minute ||= Digest::MD5.hexdigest(ChatwootHub.installation_identifier).hex % 1440
+  end
+end

config/initializers/sidekiq.rb

@@ -34,5 +34,7 @@ end
 
 # https://github.com/ondrejbartas/sidekiq-cron
 Rails.application.reloader.to_prepare do
+  # TODO: Switch to `load_from_hash!(..., source: 'schedule')` once we have a
+  # safe cleanup path for YAML-backed cron jobs already persisted in Redis.
   Sidekiq::Cron::Job.load_from_hash YAML.load_file(schedule_file) if File.exist?(schedule_file) && Sidekiq.server?
 end

config/schedule.yml

@@ -2,10 +2,12 @@
 # use https://crontab.guru/ to validate
 # validations for this file exist in /spec/configs/schedule_spec.rb
 
-# executed At 12:00 on every day-of-month.
+# executed daily at 0000 UTC
+# schedules daily deferred jobs at stable times for each installation
+# keep the existing schedule key while the cron loader still uses load_from_hash
 internal_check_new_versions_job:
-  cron: '0 12 */1 * *'
-  class: 'Internal::CheckNewVersionsJob'
+  cron: '0 0 * * *'
+  class: 'Internal::TriggerDailyScheduledItemsJob'
   queue: scheduled_jobs
 # # executed At every 5th minute..
 trigger_scheduled_items_job:

spec/jobs/internal/trigger_daily_scheduled_items_job_spec.rb

@@ -0,0 +1,39 @@
+require 'rails_helper'
+
+RSpec.describe Internal::TriggerDailyScheduledItemsJob do
+  subject(:perform_job) { described_class.perform_now }
+
+  let(:installation_id) { 'test-installation-id' }
+  let(:designated_minute) { Digest::MD5.hexdigest(installation_id).hex % 1440 }
+  let(:scheduled_time) { Time.current.utc.beginning_of_day + designated_minute.minutes }
+  let(:configured_job) { instance_double(ActiveJob::ConfiguredJob, perform_later: true) }
+
+  before do
+    allow(ChatwootHub).to receive(:installation_identifier).and_return(installation_id)
+    allow(Internal::CheckNewVersionsJob).to receive(:set).and_return(configured_job)
+  end
+
+  it 'enqueues the job' do
+    expect { described_class.perform_later }.to have_enqueued_job(described_class)
+      .on_queue('scheduled_jobs')
+  end
+
+  it 'schedules the version check at a stable minute in production' do
+    allow(Rails.env).to receive(:production?).and_return(true)
+
+    travel_to Time.zone.parse('2026-03-17 08:00:00 UTC') do
+      perform_job
+
+      expect(Internal::CheckNewVersionsJob).to have_received(:set).with(wait_until: scheduled_time)
+      expect(configured_job).to have_received(:perform_later)
+    end
+  end
+
+  it 'does not schedule the version check outside production' do
+    allow(Rails.env).to receive(:production?).and_return(false)
+
+    perform_job
+
+    expect(Internal::CheckNewVersionsJob).not_to have_received(:set)
+  end
+end