Show a maintenance window

Per-database-server offsets will be added in a separate commit

refs FOO-1600

Change-Id: I836691ba18b373717f139e116b9b91376f67b682
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/260356
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Ethan Vizitei <evizitei@instructure.com>
QA-Review: Jacob Burroughs <jburroughs@instructure.com>
Product-Review: Jacob Burroughs <jburroughs@instructure.com>

Gemfile.d/app.rb

@@ -128,6 +128,8 @@ gem 'twilio-ruby', '5.36.0', require: false
 gem 'tzinfo', '1.2.7'
 gem 'vault', '0.15.0', require: false
 gem 'vericite_api', '1.5.3'
+gem 'week_of_month', '1.2.5',
+  github: 'instructure/week-of-month', ref: 'b3013639e9474f302b5a6f27e4e45313e8d24902'
 gem 'will_paginate', '3.3.0', require: false # required for folio-pagination
 
 path 'engines' do

app/views/accounts/settings.html.erb

@@ -134,6 +134,12 @@
                   <%= f.time_zone_select :default_time_zone, I18nTimeZone.us_zones, :model => I18nTimeZone %>
                 </td>
               </tr>
+              <% if @account.shard.database_server.maintenance_window_start_hour %>
+              <tr>
+                <td></td>
+                <td> <%= render partial: 'shared/maintenance_window', locals: { database_server: @account.shard.database_server } %> </td>
+              </tr>
+              <% end %>
               <%= f.fields_for :settings do |settings| %>
                 <% if @account.grants_right?(@current_user, :manage_site_settings) %>
                   <tr>

app/views/profile/profile.html.erb

@@ -157,6 +157,12 @@
       <span class="edit_data"><%= f.time_zone_select :time_zone, I18nTimeZone.us_zones, :model => I18nTimeZone, :default => (@domain_root_account.try(:default_time_zone) || "Mountain Time (US & Canada)") %></span>
     </td>
   </tr>
+  <% if @user.shard.database_server.maintenance_window_start_hour %>
+  <tr>
+    <td></td>
+    <td> <%= render partial: 'shared/maintenance_window', locals: { database_server: @user.shard.database_server } %> </td>
+  </tr>
+  <% end %>
   <% if @domain_root_account == Account.default %>
     <tr>
       <td colspan="2">

app/views/shared/_maintenance_window.html.erb

@@ -0,0 +1,9 @@
+<% next_window = database_server.next_maintenance_window %>
+<%= t("Maintenance windows: %{days} %{weekday} of the month from %{time_range} (%{utc_time_range} UTC )",
+            { days: database_server.maintenance_window_weeks_of_month.map(&:ordinalize).to_sentence,
+                weekday: I18n.t('date.day_names')[next_window[0].wday],
+                time_range: time_string(next_window[0], next_window[1]),
+                utc_time_range: time_string(next_window[0], next_window[1], ActiveSupport::TimeZone['UTC']) }) %>
+<br/>
+<%= t("Next maintenance at: %{window}", {
+    window: datetime_string(next_window[0], :verbose, next_window[1], with_weekday: true) }) %> 

config/initializers/switchman.rb

@@ -142,6 +142,43 @@ Rails.application.config.after_initialize do
       @in_current_region
     end
 
+    def next_maintenance_window
+      return nil unless maintenance_window_start_hour
+
+      start_day = DateTime.now
+      # This array is effectively 1 indexed
+      relevant_weeks = maintenance_window_weeks_of_month.map { |i| WeekOfMonth::Constant::WEEKS_IN_SEQUENCE[i] }
+      maintenance_days = relevant_weeks.map do |ordinal|
+        Time.zone.local_to_utc(start_day.send("#{ordinal}_#{maintenance_window_weekday}_in_month".downcase))
+      end + relevant_weeks.map do |ordinal|
+        Time.zone.local_to_utc((start_day + 1.month).send("#{ordinal}_#{maintenance_window_weekday}_in_month".downcase))
+      end 
+
+      next_day = maintenance_days.find { |d| d.future? }
+      # Time offsets are strange
+      start_at = next_day.utc.beginning_of_day - maintenance_window_start_hour.hours
+      end_at = start_at + maintenance_window_duration
+
+      [start_at, end_at]
+    end
+
+    def maintenance_window_start_hour
+      Setting.get('maintenance_window_start_hour', nil)&.to_i
+    end
+
+    def maintenance_window_duration
+      # ISO 8601 duration
+      ActiveSupport::Duration.parse(Setting.get('maintenance_window_duration', "PT2H"))
+    end
+
+    def maintenance_window_weekday
+      Setting.get('maintenance_window_weekday', 'thursday').downcase
+    end
+
+    def maintenance_window_weeks_of_month
+      Setting.get('maintenance_window_weeks_of_month', "1,3").split(',').map(&:to_i)
+    end
+
     def self.send_in_each_region(klass, method, enqueue_args = {}, *args)
       run_current_region_asynchronously = enqueue_args.delete(:run_current_region_asynchronously)
 

lib/text_helper.rb

@@ -60,9 +60,9 @@ module TextHelper
     end
   end
 
-  def datetime_string(start_datetime, datetime_type=:event, end_datetime=nil, shorten_midnight=false, zone=nil)
+  def datetime_string(start_datetime, datetime_type=:event, end_datetime=nil, shorten_midnight=false, zone=nil, with_weekday: false)
     zone ||= ::Time.zone
-    presenter = Utils::DatetimeRangePresenter.new(start_datetime, end_datetime, datetime_type, zone)
+    presenter = Utils::DatetimeRangePresenter.new(start_datetime, end_datetime, datetime_type, zone, with_weekday: with_weekday)
     presenter.as_string(shorten_midnight: shorten_midnight)
   end
 

lib/utils/date_presenter.rb

@@ -18,13 +18,14 @@
 
 module Utils
   class DatePresenter
-    attr_reader :date, :raw_date, :zone
+    attr_reader :date, :raw_date, :zone, :with_weekday
 
-    def initialize(date, zone=nil)
+    def initialize(date, zone=nil, with_weekday: false)
       zone ||= Time.zone
       @raw_date = date
       @date = RelativeDate.new(date, zone)
       @zone = zone
+      @with_weekday = with_weekday
     end
 
     def as_string(style=:normal)
@@ -52,7 +53,8 @@ module Utils
     end
 
     def i18n_date(format)
-      I18n.l(raw_date, format: I18n.send(:t, :"date.formats.#{format}"))
+      # Use send to prevent i18nliner trying to parse this
+      I18n.l(raw_date, format: I18n.send(:t, "date.formats.#{format}#{with_weekday ? '_with_weekday' : ''}"))
     end
 
     def special_value_type

lib/utils/datetime_range_presenter.rb

@@ -18,13 +18,14 @@
 
 module Utils
   class DatetimeRangePresenter
-    attr_reader :start, :zone
-    def initialize(datetime, end_datetime = nil, datetime_type=:event, zone=nil)
+    attr_reader :start, :zone, :with_weekday
+    def initialize(datetime, end_datetime = nil, datetime_type=:event, zone=nil, with_weekday: false)
       zone ||= ::Time.zone
       @start = datetime.in_time_zone(zone) rescue datetime
       @_finish = end_datetime.in_time_zone(zone) rescue end_datetime
       @_datetime_type = datetime_type
       @zone = zone
+      @with_weekday = with_weekday
     end
 
     def as_string(options={})
@@ -94,7 +95,7 @@ module Utils
     end
 
     def present_date(date)
-      Utils::DatePresenter.new(date.to_date, zone).as_string(date_style)
+      Utils::DatePresenter.new(date.to_date, zone, with_weekday: with_weekday).as_string(date_style)
     end
 
     def finish

spec/initializers/switchman_spec.rb

@@ -40,4 +40,68 @@ describe Switchman::Shard do
       expect(Shard.in_region('eu-west-1')).to eq([s3])
     end
   end
+
+  describe "maintenance_windows" do
+    before do
+      allow(Setting).to receive(:get).and_call_original
+    end
+
+    it 'Returns an empty window if no start is defined' do
+      allow(Setting).to receive(:get).with("maintenance_window_start_hour", anything).and_return(nil)
+
+      expect(DatabaseServer.all.first.next_maintenance_window).to be(nil)
+    end
+
+    it 'Returns a window of the correct duration' do
+      allow(Setting).to receive(:get).with("maintenance_window_start_hour", anything).and_return('0')
+      allow(Setting).to receive(:get).with("maintenance_window_duration", anything).and_return('PT3H')
+
+      window = DatabaseServer.all.first.next_maintenance_window
+
+      expect(window[1] - window[0]).to eq(3.hours)
+    end
+
+    it 'Returns a window starting at the correct time' do
+      allow(Setting).to receive(:get).with("maintenance_window_start_hour", anything).and_return('3')
+
+      window = DatabaseServer.all.first.next_maintenance_window
+
+      expect(window[0].utc.hour).to eq(21)
+
+      allow(Setting).to receive(:get).with("maintenance_window_start_hour", anything).and_return('-7')
+
+      window = DatabaseServer.all.first.next_maintenance_window
+
+      expect(window[0].utc.hour).to eq(7)
+    end
+
+    it 'Returns a window on the correct day' do
+      allow(Setting).to receive(:get).with("maintenance_window_start_hour", anything).and_return('0')
+      allow(Setting).to receive(:get).with("maintenance_window_weekday", anything).and_return('Tuesday')
+
+      window = DatabaseServer.all.first.next_maintenance_window
+
+      expect(window[0].wday).to eq(Date::DAYNAMES.index('Tuesday'))
+    end
+
+    it 'Returns a window on the correct day of the month' do
+      allow(Setting).to receive(:get).with("maintenance_window_start_hour", anything).and_return('0')
+      allow(Setting).to receive(:get).with("maintenance_window_weekday", anything).and_return('Tuesday')
+      allow(Setting).to receive(:get).with("maintenance_window_weeks_of_month", anything).and_return('2,4')
+
+      Timecop.freeze(Time.utc(2021,3,1,12,0)) do
+        window = DatabaseServer.all.first.next_maintenance_window
+
+        # The 9th was the second tuesday of that month
+        expect(window[0].day).to eq(9)
+      end
+
+      Timecop.freeze(Time.utc(2021,3,10,12,0)) do
+        window = DatabaseServer.all.first.next_maintenance_window
+
+        # The 23rd was the fourth tuesday of that month
+        expect(window[0].day).to eq(23)
+      end
+    end
+  end
 end