Email participants of on-call rotation when alerts occur

When an alert comes in through an HTTP integration or Prometheus
integration, we'll find the user(s) who are currently on-call
and notify them of the alert. Also sends out a notification
when an alert is resolved. The email sent matches the email
sent if the project has alert emails configured.

app/services/concerns/alert_management/alert_processing.rb

@@ -125,3 +125,5 @@ module AlertManagement
     end
   end
 end
+
+AlertManagement::AlertProcessing.prepend_ee_mod

ee/app/finders/incident_management/oncall_users_finder.rb

+# frozen_string_literal: true
+
+module IncidentManagement
+  # Returns users who are oncall by reading shifts from the DB.
+  # The DB is the historical record, so we should adhere to it
+  # when it is available. If rotations are missing persited
+  # shifts for some reason, we'll fallback to a generated shift.
+  # It may also be possible that no one is on call for a rotation.
+  class OncallUsersFinder
+    include Gitlab::Utils::StrongMemoize
+
+    # @param project [Project]
+    # @option oncall_at [ActiveSupport::TimeWithZone]
+    #                   Limits users to only those
+    #                   on-call at the specified time.
+    def initialize(project, oncall_at: Time.current)
+      @project = project
+      @oncall_at = oncall_at
+    end
+
+    # @return [User::ActiveRecord_Relation]
+    def execute
+      return User.none unless Gitlab::IncidentManagement.oncall_schedules_available?(project)
+      return User.none unless user_ids.present?
+
+      User.id_in(user_ids)
+    end
+
+    private
+
+    attr_reader :project, :oncall_at
+
+    def user_ids
+      strong_memoize(:user_ids) do
+        user_ids_for_persisted_shifts.concat(user_ids_for_predicted_shifts).uniq
+      end
+    end
+
+    def user_ids_for_persisted_shifts
+      ids_for_persisted_shifts.flat_map(&:last)
+    end
+
+    def rotation_ids_for_persisted_shifts
+      ids_for_persisted_shifts.flat_map(&:first)
+    end
+
+    # @return [Array<[rotation_id, user_id]>]
+    # @example - [ [1, 16], [2, 200] ]
+    def ids_for_persisted_shifts
+      strong_memoize(:ids_for_persisted_shifts) do
+        project.incident_management_oncall_rotations
+          .merge(IncidentManagement::OncallShift.for_timestamp(oncall_at))
+          .pluck_id_and_user_id
+      end
+    end
+
+    def user_ids_for_predicted_shifts
+      rotations_without_persisted_shifts.map do |rotation|
+        next unless shift = IncidentManagement::OncallShiftGenerator.new(rotation).for_timestamp(oncall_at)
+
+        shift.participant.user_id
+      end
+    end
+
+    def rotations_without_persisted_shifts
+      project.incident_management_oncall_rotations
+        .except_ids(rotation_ids_for_persisted_shifts)
+        .with_shift_generation_associations
+    end
+  end
+end

ee/app/models/ee/project.rb

@@ -103,6 +103,7 @@ module EE
       has_many :sourced_pipelines, class_name: 'Ci::Sources::Project', foreign_key: :source_project_id
 
       has_many :incident_management_oncall_schedules, class_name: 'IncidentManagement::OncallSchedule', inverse_of: :project
+      has_many :incident_management_oncall_rotations, class_name: 'IncidentManagement::OncallRotation', through: :incident_management_oncall_schedules, source: :rotations
 
       elastic_index_dependant_association :issues, on_change: :visibility_level
 

ee/app/models/incident_management/oncall_participant.rb

@@ -11,8 +11,6 @@ module IncidentManagement
     belongs_to :user, class_name: 'User', foreign_key: :user_id
     has_many :shifts, class_name: 'OncallShift', inverse_of: :participant, foreign_key: :participant_id
 
-    scope :ordered_asc, -> { order(id: :asc) }
-
     # Uniqueness validations added here should be duplicated
     # in IncidentManagement::OncallRotation::CreateService
     # as bulk insertion skips validations

ee/app/models/incident_management/oncall_rotation.rb

@@ -13,7 +13,8 @@ module IncidentManagement
     NAME_LENGTH = 200
 
     belongs_to :schedule, class_name: 'OncallSchedule', inverse_of: 'rotations', foreign_key: 'oncall_schedule_id'
-    has_many :participants, class_name: 'OncallParticipant', inverse_of: :rotation
+    # Note! If changing the order of participants, also change the :with_shift_generation_associations scope.
+    has_many :participants, -> { order(id: :asc) }, class_name: 'OncallParticipant', inverse_of: :rotation
     has_many :users, through: :participants
     has_many :shifts, class_name: 'OncallShift', inverse_of: :rotation, foreign_key: :rotation_id
 
@@ -23,9 +24,20 @@ module IncidentManagement
     validates :length_unit, presence: true
 
     scope :started, -> { where('starts_at < ?', Time.current) }
+    scope :except_ids, -> (ids) { where.not(id: ids) }
+    scope :with_shift_generation_associations, -> do
+      joins(:participants, :schedule)
+        .distinct
+        .includes(:participants, :schedule)
+        .order(:id, 'incident_management_oncall_participants.id ASC')
+    end
 
     delegate :project, to: :schedule
 
+    def self.pluck_id_and_user_id
+      joins(shifts: { participant: :user }).pluck(:id, 'users.id')
+    end
+
     def shift_duration
       # As length_unit is an enum, input is guaranteed to be appropriate
       length.public_send(length_unit) # rubocop:disable GitlabSecurity/PublicSend

ee/app/models/incident_management/oncall_schedule.rb

@@ -11,7 +11,7 @@ module IncidentManagement
     DESCRIPTION_LENGTH = 1000
 
     belongs_to :project, inverse_of: :incident_management_oncall_schedules
-    has_many :rotations, class_name: 'OncallRotation'
+    has_many :rotations, class_name: 'OncallRotation', inverse_of: :schedule
     has_many :participants, class_name: 'OncallParticipant', through: :rotations
 
     has_internal_id :iid, scope: :project

ee/app/models/incident_management/oncall_shift.rb

@@ -21,6 +21,10 @@ module IncidentManagement
 
       where("tstzrange(starts_at, ends_at, '[)') && tstzrange(?, ?, '[)')", starts_at, ends_at)
     end
+    scope :for_timestamp, -> (timestamp) do
+      where('incident_management_oncall_shifts.starts_at <= :timestamp AND '\
+            'incident_management_oncall_shifts.ends_at > :timestamp', timestamp: timestamp)
+    end
 
     private
 

ee/app/services/concerns/ee/alert_management/alert_processing.rb

+# frozen_string_literal: true
+
+module EE
+  module AlertManagement
+    module AlertProcessing
+      extend ::Gitlab::Utils::Override
+
+      private
+
+      override :complete_post_processing_tasks
+      def complete_post_processing_tasks
+        super
+
+        notify_oncall if oncall_notification_recipients.present?
+      end
+
+      def notify_oncall
+        notification_service
+          .async
+          .notify_oncall_users_of_alert(oncall_notification_recipients.to_a, alert)
+      end
+
+      def oncall_notification_recipients
+        strong_memoize(:oncall_notification_recipients) do
+          ::IncidentManagement::OncallUsersFinder.new(project).execute
+        end
+      end
+    end
+  end
+end

ee/app/services/ee/notification_service.rb

@@ -66,6 +66,12 @@ module EE
       mailer.provisioned_member_access_granted_email(group_member.id).deliver_later
     end
 
+    def notify_oncall_users_of_alert(users, alert)
+      users.each do |user|
+        mailer.prometheus_alert_fired_email(alert.project, user, alert).deliver_later
+      end
+    end
+
     private
 
     def add_mr_approvers_email(merge_request, approvers, current_user)

ee/lib/incident_management/oncall_shift_generator.rb

@@ -124,7 +124,7 @@ module IncidentManagement
     end
 
     def participants
-      @participants ||= rotation.participants.ordered_asc
+      @participants ||= rotation.participants
     end
 
     def rotation_starts_at

ee/spec/finders/incident_management/oncall_users_finder_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe IncidentManagement::OncallUsersFinder do
+  let_it_be_with_refind(:project) { create(:project) }
+
+  # Project 1             Shift 1          Shift 2          Shift 3
+  # s1 -> r1 [p1]     | user 1; saved | user 1; unsaved | user 1; unsaved |
+  #    -> r2 [p1, p2] | user 2; saved | user 3; saved   | user 2; unsaved |
+  # s2 -> r1 [p1]     | user 4; saved | user 4; unsaved | user 4; unsaved |
+  #    -> r2 [p1]     | user 1; saved | user 1; unsaved | user 1; unsaved |
+  #    -> r3          |     N/A       |      N/A        |       N/A       |
+  #
+  # Project 2
+  # s1 -> r1 [p1, p2] | user 5; saved | user 2; saved   | user 5; unsaved |
+
+  # Schedule 1 / Rotation 1
+  let_it_be(:s1) { create(:incident_management_oncall_schedule, project: project) }
+  let_it_be(:s1_r1) { create(:incident_management_oncall_rotation, :with_participant, schedule: s1) }
+  let_it_be(:s1_r1_p1) { s1_r1.participants.first }
+  let_it_be(:user_1) { s1_r1_p1.user }
+  let_it_be(:s1_r1_shift1) { create(:incident_management_oncall_shift, participant: s1_r1_p1) }
+
+  # Schedule 1 / Rotation 2
+  let_it_be(:s1_r2) { create(:incident_management_oncall_rotation, :with_participant, schedule: s1) }
+  let_it_be(:s1_r2_p1) { s1_r2.participants.first }
+  let_it_be(:user_2) { s1_r2_p1.user }
+  let_it_be(:s1_r2_shift1) { create(:incident_management_oncall_shift, participant: s1_r2_p1) }
+  let_it_be(:s1_r2_p2) { create(:incident_management_oncall_participant, rotation: s1_r2) }
+  let_it_be(:user_3) { s1_r2_p2.user }
+  let_it_be(:s1_r2_shift2) { create(:incident_management_oncall_shift, participant: s1_r2_p2, starts_at: s1_r2_shift1.ends_at) }
+
+  # Schedule 2 / Rotation 1
+  let_it_be(:s2) { create(:incident_management_oncall_schedule, project: project) }
+  let_it_be(:s2_r1) { create(:incident_management_oncall_rotation, :with_participant, schedule: s2) }
+  let_it_be(:s2_r1_p1) { s2_r1.participants.first }
+  let_it_be(:user_4) { s2_r1_p1.user }
+  let_it_be(:s2_r1_shift1) { create(:incident_management_oncall_shift, participant: s2_r1_p1) }
+
+  # Schedule 2 / Rotation 2 - has same user as s1_r1_p1
+  let_it_be(:s2_r2) { create(:incident_management_oncall_rotation, schedule: s2) }
+  let_it_be(:s2_r2_p1) { create(:incident_management_oncall_participant, user: user_1, rotation: s2_r2) }
+  let_it_be(:s2_r2_shift1) { create(:incident_management_oncall_shift, participant: s2_r2_p1) }
+
+  # Schedule 2 / Rotation 3 - has no participants
+  let_it_be(:s2_r3) { create(:incident_management_oncall_rotation, schedule: s2) }
+
+  # Other Project - has same user as s1_r2_p1
+  let_it_be(:proj2_s1_r1_p1) { create(:incident_management_oncall_participant) } # user_5
+  let_it_be(:proj2_s1_r1_shift1) { create(:incident_management_oncall_shift, participant: proj2_s1_r1_p1) }
+  let_it_be(:proj2_s1_r1) { proj2_s1_r1_p1.rotation }
+  let_it_be(:proj2_s1_r1_p2) { create(:incident_management_oncall_participant, :with_developer_access, user: user_2, rotation: proj2_s1_r1) }
+  let_it_be(:proj2_s1_r1_shift2) { create(:incident_management_oncall_shift, participant: proj2_s1_r1_p2, starts_at: proj2_s1_r1_shift1.ends_at) }
+
+  let(:oncall_at) { Time.current }
+
+  describe '#execute' do
+    subject(:execute) { described_class.new(project, oncall_at: oncall_at).execute }
+
+    context 'when feature is available' do
+      before do
+        stub_licensed_features(oncall_schedules: true)
+      end
+
+      context 'without parameters uses current time' do
+        subject(:execute) { described_class.new(project).execute }
+
+        it { is_expected.to contain_exactly(user_1, user_2, user_4) }
+      end
+
+      context 'with :oncall_at parameter specified' do
+        let(:during_first_shift) { Time.current }
+        let(:during_second_shift) { s1_r2_shift2.starts_at + 5.minutes }
+        let(:after_second_shift) { s1_r2_shift2.ends_at + 5.minutes }
+        let(:before_shifts) { s1_r1.starts_at - 15.minutes }
+
+        context 'with all persisted shifts for oncall_at time' do
+          let(:oncall_at) { during_first_shift }
+
+          it { is_expected.to contain_exactly(user_1, user_2, user_4) }
+
+          it 'does not attempt to generate shifts' do
+            expect(IncidentManagement::OncallShiftGenerator).not_to receive(:new)
+
+            execute
+          end
+        end
+
+        context 'with some persisted shifts for oncall_at time' do
+          let(:oncall_at) { during_second_shift }
+
+          it { is_expected.to contain_exactly(user_1, user_3, user_4) }
+
+          it 'does not run additional queries for each persisted shift' do
+            query_count = ActiveRecord::QueryRecorder.new { execute }
+
+            create(:incident_management_oncall_shift, participant: s1_r1_p1, starts_at: s1_r1_shift1.ends_at)
+
+            expect { described_class.new(project, oncall_at: oncall_at).execute }.not_to exceed_query_limit(query_count)
+          end
+        end
+
+        context 'with no persisted shifts for oncall_at time' do
+          let(:oncall_at) { after_second_shift }
+
+          it { is_expected.to contain_exactly(user_1, user_2, user_4) }
+        end
+
+        context 'before rotations have started' do
+          let(:oncall_at) { before_shifts }
+
+          it { is_expected.to be_empty }
+        end
+
+        it 'does not require additional queries to generate shifts' do
+          query_count = ActiveRecord::QueryRecorder.new { described_class.new(project, oncall_at: during_first_shift).execute }
+
+          expect { described_class.new(project, oncall_at: after_second_shift).execute }
+            .not_to exceed_query_limit(query_count)
+        end
+      end
+    end
+
+    context 'when feature is not avaiable' do
+      before do
+        stub_licensed_features(oncall_schedules: false)
+      end
+
+      it { is_expected.to eq(IncidentManagement::OncallParticipant.none) }
+    end
+  end
+end

ee/spec/lib/incident_management/oncall_shift_generator_spec.rb

@@ -4,7 +4,7 @@ require 'spec_helper'
 
 RSpec.describe IncidentManagement::OncallShiftGenerator do
   let_it_be(:rotation_start_time) { Time.parse('2020-12-08 00:00:00 UTC').utc }
-  let_it_be(:rotation) { create(:incident_management_oncall_rotation, starts_at: rotation_start_time, length: 5, length_unit: :days) }
+  let_it_be_with_reload(:rotation) { create(:incident_management_oncall_rotation, starts_at: rotation_start_time, length: 5, length_unit: :days) }
 
   let(:current_time) { Time.parse('2020-12-08 15:00:00 UTC').utc }
   let(:shift_length) { rotation.shift_duration }

ee/spec/models/incident_management/oncall_participant_spec.rb

@@ -38,18 +38,6 @@ RSpec.describe IncidentManagement::OncallParticipant do
     end
   end
 
-  describe 'scopes' do
-    describe '.ordered_asc' do
-      let_it_be(:participant1) { create(:incident_management_oncall_participant, :with_developer_access, rotation: rotation) }
-      let_it_be(:participant2) { create(:incident_management_oncall_participant, :with_developer_access, rotation: rotation) }
-      let_it_be(:participant3) { create(:incident_management_oncall_participant, :with_developer_access, rotation: rotation) }
-
-      subject { described_class.ordered_asc }
-
-      it { is_expected.to eq([participant1, participant2, participant3]) }
-    end
-  end
-
   private
 
   def remove_user_from_project(user, project)

ee/spec/models/incident_management/oncall_rotation_spec.rb

@@ -6,10 +6,10 @@ RSpec.describe IncidentManagement::OncallRotation do
   let_it_be(:schedule) { create(:incident_management_oncall_schedule) }
 
   describe '.associations' do
-    it { is_expected.to belong_to(:schedule) }
-    it { is_expected.to have_many(:participants) }
+    it { is_expected.to belong_to(:schedule).class_name('OncallSchedule').inverse_of(:rotations) }
+    it { is_expected.to have_many(:participants).order(id: :asc).class_name('OncallParticipant').inverse_of(:rotation) }
     it { is_expected.to have_many(:users).through(:participants) }
-    it { is_expected.to have_many(:shifts) }
+    it { is_expected.to have_many(:shifts).class_name('OncallShift').inverse_of(:rotation) }
   end
 
   describe '.validations' do

ee/spec/models/incident_management/oncall_schedule_spec.rb

@@ -7,7 +7,7 @@ RSpec.describe IncidentManagement::OncallSchedule do
 
   describe '.associations' do
     it { is_expected.to belong_to(:project) }
-    it { is_expected.to have_many(:rotations) }
+    it { is_expected.to have_many(:rotations).inverse_of(:schedule) }
     it { is_expected.to have_many(:participants).through(:rotations) }
   end
 

ee/spec/models/incident_management/oncall_shift_spec.rb

@@ -45,36 +45,36 @@ RSpec.describe IncidentManagement::OncallShift do
   end
 
   describe 'scopes' do
-    describe '.for_timeframe' do
-      let_it_be(:monday) { Time.current.next_week(:monday) }
-      let_it_be(:tuesday) { monday + 1.day }
-      let_it_be(:wednesday) { tuesday + 1.day }
-      let_it_be(:thursday) { wednesday + 1.day }
-      let_it_be(:friday) { thursday + 1.day }
-      let_it_be(:saturday) { friday + 1.day }
-      let_it_be(:sunday) { saturday + 1.day }
-
-      # Using multiple participants in different rotations
-      # to be able to simultaneously save shifts which would
-      # conflict if they were part of the same rotation
-      let_it_be(:participant2) { create(:incident_management_oncall_participant, :with_developer_access) }
-      let_it_be(:participant3) { create(:incident_management_oncall_participant, :with_developer_access) }
-
-      # First rotation
-      let_it_be(:mon_to_tue) { create_shift(monday, tuesday, participant) }
-      let_it_be(:tue_to_wed) { create_shift(tuesday, wednesday, participant) }
-      let_it_be(:wed_to_thu) { create_shift(wednesday, thursday, participant) }
-      let_it_be(:thu_to_fri) { create_shift(thursday, friday, participant) }
-      let_it_be(:fri_to_sat) { create_shift(friday, saturday, participant) }
-      let_it_be(:sat_to_sun) { create_shift(saturday, sunday, participant) }
-
-      # Second rotation
-      let_it_be(:mon_to_thu) { create_shift(monday, thursday, participant2) }
-      let_it_be(:fri_to_sun) { create_shift(friday, sunday, participant2) }
-
-      # Third rotation
-      let_it_be(:tue_to_sun) { create_shift(wednesday, sunday, participant3) }
+    let_it_be(:monday) { Time.current.next_week(:monday) }
+    let_it_be(:tuesday) { monday + 1.day }
+    let_it_be(:wednesday) { tuesday + 1.day }
+    let_it_be(:thursday) { wednesday + 1.day }
+    let_it_be(:friday) { thursday + 1.day }
+    let_it_be(:saturday) { friday + 1.day }
+    let_it_be(:sunday) { saturday + 1.day }
+
+    # Using multiple participants in different rotations
+    # to be able to simultaneously save shifts which would
+    # conflict if they were part of the same rotation
+    let_it_be(:participant2) { create(:incident_management_oncall_participant, :with_developer_access) }
+    let_it_be(:participant3) { create(:incident_management_oncall_participant, :with_developer_access) }
+
+    # First rotation
+    let_it_be(:mon_to_tue) { create_shift(monday, tuesday, participant) }
+    let_it_be(:tue_to_wed) { create_shift(tuesday, wednesday, participant) }
+    let_it_be(:wed_to_thu) { create_shift(wednesday, thursday, participant) }
+    let_it_be(:thu_to_fri) { create_shift(thursday, friday, participant) }
+    let_it_be(:fri_to_sat) { create_shift(friday, saturday, participant) }
+    let_it_be(:sat_to_sun) { create_shift(saturday, sunday, participant) }
+
+    # Second rotation
+    let_it_be(:mon_to_thu) { create_shift(monday, thursday, participant2) }
+    let_it_be(:fri_to_sun) { create_shift(friday, sunday, participant2) }
+
+    # Third rotation
+    let_it_be(:tue_to_sun) { create_shift(tuesday, sunday, participant3) }
 
+    describe '.for_timeframe' do
       subject(:shifts) { described_class.for_timeframe(wednesday, saturday) }
 
       it 'includes shifts which cover the timeframe' do
@@ -102,10 +102,32 @@ RSpec.describe IncidentManagement::OncallShift do
     describe '.order_starts_at_desc' do
       subject { described_class.order_starts_at_desc }
 
-      let_it_be(:shift1) { create_shift(Time.current, Time.current + 1.hour, participant) }
-      let_it_be(:shift2) { create_shift(Time.current + 2.hours, Time.current + 3.hours, participant) }
+      it do
+        is_expected.to eq [
+          sat_to_sun,
+          fri_to_sun,
+          fri_to_sat,
+          thu_to_fri,
+          wed_to_thu,
+          tue_to_sun,
+          tue_to_wed,
+          mon_to_thu,
+          mon_to_tue
+        ]
+      end
+    end
+
+    describe '.for_timestamp' do
+      subject(:shifts) { described_class.for_timestamp(wednesday) }
 
-      it { is_expected.to eq [shift2, shift1]}
+      it 'includes shifts which cover the timestamp' do
+        expect(shifts).to contain_exactly(
+          mon_to_thu, # Covers timestamp
+          wed_to_thu, # Starts at timestamp
+          tue_to_sun # Covers timestamp
+        )
+        # Notable excluded shift: tue_to_wed (Ends at timestamp)
+      end
     end
   end
 

ee/spec/models/project_spec.rb

@@ -55,6 +55,7 @@ RSpec.describe Project do
     it { is_expected.to have_many(:approval_rules) }
 
     it { is_expected.to have_many(:incident_management_oncall_schedules).class_name('IncidentManagement::OncallSchedule') }
+    it { is_expected.to have_many(:incident_management_oncall_rotations).through(:incident_management_oncall_schedules).source(:rotations) }
 
     describe 'approval_rules association' do
       let_it_be(:rule, reload: true) { create(:approval_project_rule) }

ee/spec/services/alert_management/process_prometheus_alert_service_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe AlertManagement::ProcessPrometheusAlertService do
+  let_it_be(:project, refind: true) { create(:project) }
+
+  before do
+    allow(ProjectServiceWorker).to receive(:perform_async)
+  end
+
+  describe '#execute' do
+    let(:service) { described_class.new(project, payload) }
+
+    subject(:execute) { service.execute }
+
+    context 'when alert payload is valid' do
+      let(:parsed_payload) { Gitlab::AlertManagement::Payload.parse(project, payload, monitoring_tool: 'Prometheus') }
+      let(:fingerprint) { parsed_payload.gitlab_fingerprint }
+      let(:payload) do
+        {
+          'status' => 'firing',
+          'labels' => { 'alertname' => 'GitalyFileServerDown' },
+          'annotations' => { 'title' => 'Alert title' },
+          'startsAt' => '2020-04-27T10:10:22.265949279Z',
+          'generatorURL' => 'http://8d467bd4607a:9090/graph?g0.expr=vector%281%29&g0.tab=1'
+        }
+      end
+
+      context 'with on-call schedule' do
+        let_it_be(:schedule) { create(:incident_management_oncall_schedule, project: project) }
+        let_it_be(:rotation) { create(:incident_management_oncall_rotation, schedule: schedule) }
+        let_it_be(:participant) { create(:incident_management_oncall_participant, :with_developer_access, rotation: rotation) }
+        let(:notification_args) do
+          [
+            [participant.user],
+            having_attributes(class: AlertManagement::Alert, fingerprint: fingerprint)
+          ]
+        end
+
+        it_behaves_like 'Alert Notification Service sends notification email to on-call users'
+      end
+    end
+  end
+end

ee/spec/services/ee/notification_service_spec.rb

@@ -862,4 +862,18 @@ RSpec.describe EE::NotificationService, :mailer do
       end
     end
   end
+
+  context 'IncidentManagement::Oncall' do
+    describe '#notify_oncall_users_of_alert' do
+      let_it_be(:user) { create(:user) }
+      let_it_be(:alert) { create(:alert_management_alert) }
+      let_it_be(:project) { alert.project }
+
+      it 'sends an email to the specified users' do
+        expect(Notify).to receive(:prometheus_alert_fired_email).with(project, user, alert).and_call_original
+
+        subject.notify_oncall_users_of_alert([user], alert)
+      end
+    end
+  end
 end

ee/spec/services/projects/alerting/notify_service_spec.rb

@@ -6,6 +6,7 @@ RSpec.describe Projects::Alerting::NotifyService do
   let_it_be(:project, refind: true) { create(:project) }
 
   describe '#execute' do
+    let_it_be(:integration) { create(:alert_management_http_integration, project: project) }
     let(:service) { described_class.new(project, payload) }
     let(:token) { integration.token }
     let(:payload) do
@@ -14,8 +15,6 @@ RSpec.describe Projects::Alerting::NotifyService do
       }
     end
 
-    let(:integration) { create(:alert_management_http_integration, project: project) }
-
     subject { service.execute(token, integration) }
 
     context 'existing alert with same payload fingerprint' do
@@ -64,5 +63,19 @@ RSpec.describe Projects::Alerting::NotifyService do
         end
       end
     end
+
+    context 'with on-call schedules' do
+      let_it_be(:schedule) { create(:incident_management_oncall_schedule, project: project) }
+      let_it_be(:rotation) { create(:incident_management_oncall_rotation, schedule: schedule) }
+      let_it_be(:participant) { create(:incident_management_oncall_participant, :with_developer_access, rotation: rotation) }
+      let(:notification_args) do
+        [
+          [participant.user],
+          having_attributes(class: AlertManagement::Alert, title: payload['title'])
+        ]
+      end
+
+      it_behaves_like 'Alert Notification Service sends notification email to on-call users'
+    end
   end
 end

ee/spec/support/shared_examples/alert_notification_service_shared_examples.rb

+# frozen_string_literal: true
+
+RSpec.shared_examples 'Alert Notification Service sends notification email to on-call users' do
+  let(:notification_service) { instance_double(NotificationService) }
+
+  context 'with oncall schedules enabled' do
+    before do
+      stub_licensed_features(oncall_schedules: project)
+    end
+
+    it 'sends a notification' do
+      expect(NotificationService).to receive(:new).and_return(notification_service)
+
+      expect(notification_service)
+        .to receive_message_chain(:async, :notify_oncall_users_of_alert)
+        .with(*notification_args)
+
+      expect(subject).to be_success
+    end
+  end
+
+  context 'with oncall schedules disabled' do
+    it 'does not notify the on-call users' do
+      expect(NotificationService).not_to receive(:new)
+
+      expect(subject).to be_success
+    end
+  end
+end

spec/lib/gitlab/import_export/all_models.yml

@@ -561,6 +561,7 @@ project:
 - alert_management_http_integrations
 - exported_protected_branches
 - incident_management_oncall_schedules
+- incident_management_oncall_rotations
 - debian_distributions
 - merge_request_metrics
 award_emoji: