Context

I have a Rails API that is deployed at different locations, thus, using 2 different timezones: Pacific/Noumea (+11:00) and Pacific/Tahiti (-10:00).

I've configure both server to use the correct timezone:

config.time_zone = ENV.fetch('APP_TIMEZONE', 'Pacific/Noumea')

Problem

The API is validating some date range (start_at and end_at).

class DatesRangeValidator < ActiveModel::Validator
  def validate(record)
    check_end_at_is_before_now(record)
    check_end_at_is_before_start_at(record)
  end

  protected

  def check_end_at_is_before_now(record)
    return if record.end_at.blank? || record.end_at > Time.zone.now

    record.errors.add(
      :end_at,
      I18n.t("activerecord.errors.models.#{record.class.name.underscore}.attributes.end_at.before_now")
    )
  end

  def check_end_at_is_before_start_at(record)
    return if record.end_at.blank? || record.start_at.blank?
    return if record.end_at > record.start_at

    record.errors.add(
      :end_at,
      I18n.t("activerecord.errors.models.#{record.class.name.underscore}.attributes.end_at.before_start_at")
    )
  end
end

When using Pacific/Noumea timezone, it works fine because the offset is positive.

For example, when testing, the local time is 2025-03-18 10:14:00 +11:00:

• from the UI, user set end_at as 2025-03-18 10:16
• the value received in params is {"end_at"=>"2025-03-17T23:16:00.000Z"}
• Internally in the validator, Rails convert that date as 2025-03-18 10:16:00 +1100

which returns true because 2025-03-18 10:16:00 +1100 > 2025-03-18 10:14:00 +11:00.

However, when doing the same thing with Pacific/Tahiti, it does not works. Local time is 2025-03-17 13:19:00 -10:00:

• from the UI, user set end_at as 2025-03-17 13:25
• the value received in params is {"end_at"=>"2025-03-17T02:25:00.000Z"}
• Internally in the validator, Rails convert that date as 2025-03-16 16:25:00 -1000

which returns false because 2025-03-16 16:25:00 -1000 < 2025-03-17 13:19:00 -10:00.

What am I missing ? How to handle it ?