Send email when user cap is reached

When the user cap is reached a banner in the UI already notifies the
admins about it. Now the admins will also receive an email as soon as
the user cap is reached.

ee/app/mailers/ee/notify.rb

@@ -12,6 +12,7 @@ module EE
       include ::Emails::AdminNotification
       include ::Emails::Epics
       include ::Emails::Requirements
+      include ::Emails::UserCap
     end
 
     attr_reader :group

ee/app/mailers/emails/user_cap.rb

+# frozen_string_literal: true
+
+module Emails
+  module UserCap
+    def user_cap_reached(user_id)
+      user = User.find(user_id)
+      email = user.notification_email
+
+      @url_to_user_cap = 'https://docs.gitlab.com/ee/user/admin_area/settings/sign_up_restrictions.html#user-cap'
+      @url_to_pending_users = 'https://docs.gitlab.com/ee/user/admin_area/approving_users.html#view-user-sign-ups-pending-approval'
+      @url_to_manage_pending_users = 'https://docs.gitlab.com/ee/user/admin_area/approving_users.html#approve-or-reject-a-user-sign-up'
+      @url_to_adjust_user_cap = 'https://docs.gitlab.com/ee/user/admin_area/settings/sign_up_restrictions.html#set-the-user-cap-number'
+      @url_to_docs = 'https://docs.gitlab.com/'
+      @url_to_support = 'https://about.gitlab.com/support/'
+
+      mail to: email, subject: s_('AdminUsers|Important information about usage on your GitLab instance')
+    end
+  end
+end

ee/app/views/notify/user_cap_reached.html.haml

+%p
+  = s_('AdminUsers|Your GitLab instance has reached the maximum allowed %{user_doc_link} set by an instance admin.').html_safe % { user_doc_link: link_to(s_('AdminUsers|user cap'), @url_to_user_cap) }
+
+%p
+  %b= s_('AdminUsers|What does this mean?')
+  = s_('AdminUsers|Users can still be invited to your instance and/or add themselves if permitted based on your settings. They will not have access to your instance, nor count towards your subscribed seat count until you %{approve_link}.').html_safe % { approve_link: link_to(s_('AdminUsers|approve them'), @url_to_manage_pending_users) }
+
+%p
+  %b= s_('AdminUsers|What can I do?')
+  = s_('AdminUsers|Here are some helpful links to help you manage your instance:')
+
+%ul
+  %li= link_to s_('AdminUsers|View pending member requests'), @url_to_pending_users
+  %li= link_to s_('AdminUsers|Manage (accept/reject) pending user sign ups'), @url_to_manage_pending_users
+  %li= link_to s_('AdminUsers|Adjust the user cap setting on your instance'), @url_to_adjust_user_cap
+
+%p
+  = s_('AdminUsers|If you have any questions about this process please consult our %{doc_link} or %{support_link}.').html_safe % { doc_link: link_to(s_('AdminUsers|docs'), @url_to_docs), support_link: link_to(s_('AdminUsers|contact our support team'), @url_to_support) }

ee/app/views/notify/user_cap_reached.text.erb

+<%= s_('AdminUsers|Your GitLab instance has reached the maximum allowed %{user_doc_link} set by an instance admin.') % { user_doc_link: "#{s_('AdminUsers|user cap')} #{@url_to_user_cap}" } %>
+
+<%= s_('AdminUsers|What does this mean?') %>
+<%= s_('AdminUsers|Users can still be invited to your instance and/or add themselves if permitted based on your settings. They will not have access to your instance, nor count towards your subscribed seat count until you %{approve_link}.') % { approve_link: "#{s_('AdminUsers|approve them')} #{@url_to_manage_pending_users}" } %>
+
+<%= s_('AdminUsers|What can I do?') %>
+<%= s_('AdminUsers|Here are some helpful links to help you manage your instance:') %>
+
+<%= s_('AdminUsers|View pending member requests') %> <%= @url_to_pending_users %>
+<%= s_('AdminUsers|Manage (accept/reject) pending user sign ups') %> <%= @url_to_manage_pending_users %>
+<%= s_('AdminUsers|Adjust the user cap setting on your instance') %> <%= @url_to_adjust_user_cap %>
+
+<%= s_('AdminUsers|If you have any questions about this process please consult our %{doc_link} or %{support_link}.') % { doc_link: "#{s_('AdminUsers|docs')} #{@url_to_docs}", support_link: "#{s_('AdminUsers|contact our support team')} #{@url_to_support}" } %>

ee/app/workers/set_user_status_based_on_user_cap_setting_worker.rb

@@ -2,6 +2,7 @@
 
 class SetUserStatusBasedOnUserCapSettingWorker
   include ApplicationWorker
+  include ::Gitlab::Utils::StrongMemoize
 
   feature_category :users
 
@@ -12,7 +13,11 @@ class SetUserStatusBasedOnUserCapSettingWorker
 
     return unless user.blocked_pending_approval?
     return if user_cap_max.nil?
-    return if current_billable_users_count >= user_cap_max
+
+    if user_cap_reached?
+      send_user_cap_reached_email
+      return
+    end
 
     if user.activate
       # Resends confirmation email if the user isn't confirmed yet.
@@ -28,10 +33,22 @@ class SetUserStatusBasedOnUserCapSettingWorker
   private
 
   def user_cap_max
+    strong_memoize(:user_cap_max) do
       ::Gitlab::CurrentSettings.new_user_signups_cap
     end
+  end
 
   def current_billable_users_count
     User.billable.count
   end
+
+  def user_cap_reached?
+    current_billable_users_count >= user_cap_max
+  end
+
+  def send_user_cap_reached_email
+    User.admins.active.each do |user|
+      ::Notify.user_cap_reached(user.id).deliver_later
+    end
+  end
 end

ee/changelogs/unreleased/244529_send_email_when_user_cap_is_reached.yml

+---
+title: Send email when user cap is reached
+merge_request: 53489
+author:
+type: changed

ee/spec/mailers/emails/user_cap_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Emails::UserCap do
+  include EmailSpec::Matchers
+
+  let_it_be(:user) { create(:user) }
+
+  describe "#user_cap_reached" do
+    subject { Notify.user_cap_reached(user.id) }
+
+    it { is_expected.to have_subject('Important information about usage on your GitLab instance') }
+    it { is_expected.to be_delivered_to([user.notification_email]) }
+    it { is_expected.to have_body_text('Your GitLab instance has reached the maximum allowed') }
+    it { is_expected.to have_body_text('user cap') }
+  end
+end

ee/spec/workers/set_user_status_based_on_user_cap_setting_worker_spec.rb

@@ -15,6 +15,25 @@ RSpec.describe SetUserStatusBasedOnUserCapSettingWorker, type: :worker do
       allow(Gitlab::CurrentSettings).to receive(:new_user_signups_cap).and_return(new_user_signups_cap)
     end
 
+    shared_examples 'keeps user in blocked_pending_approval state' do
+      it 'keeps the user in blocked_pending_approval state' do
+        subject
+
+        expect(user.reload).to be_blocked_pending_approval
+      end
+    end
+
+    shared_examples 'sends email to every active admin' do
+      let_it_be(:active_admin) { create(:user, :admin, state: 'active') }
+      let_it_be(:inactive_admin) { create(:user, :admin, :deactivated) }
+
+      it 'sends an email to every active admin' do
+        expect(::Notify).to receive(:user_cap_reached).with(active_admin.id).once.and_call_original
+
+        subject
+      end
+    end
+
     context 'when user is not blocked_pending_approval' do
       let(:user) { active_user }
 
@@ -98,13 +117,19 @@ RSpec.describe SetUserStatusBasedOnUserCapSettingWorker, type: :worker do
     end
 
     context 'when current billable user count is equal to user cap' do
-      let(:new_user_signups_cap) { 1 }
-
-      it 'keeps the user in blocked_pending_approval state' do
-        subject
+      let(:new_user_signups_cap) { 2 }
 
-        expect(user.reload).to be_blocked_pending_approval
+      include_examples 'keeps user in blocked_pending_approval state'
+      include_examples 'sends email to every active admin'
     end
+
+    context 'when current billable user count is greater than user cap' do
+      let_it_be(:another_active_user) { create(:user, state: 'active') }
+
+      let(:new_user_signups_cap) { 1 }
+
+      include_examples 'keeps user in blocked_pending_approval state'
+      include_examples 'sends email to every active admin'
     end
   end
 end

locale/gitlab.pot

@@ -2297,6 +2297,9 @@ msgstr ""
 msgid "AdminUsers|Active"
 msgstr ""
 
+msgid "AdminUsers|Adjust the user cap setting on your instance"
+msgstr ""
+
 msgid "AdminUsers|Admin"
 msgstr ""
 
@@ -2390,6 +2393,15 @@ msgstr ""
 msgid "AdminUsers|For more information, please refer to the %{link_start}user account deletion documentation.%{link_end}"
 msgstr ""
 
+msgid "AdminUsers|Here are some helpful links to help you manage your instance:"
+msgstr ""
+
+msgid "AdminUsers|If you have any questions about this process please consult our %{doc_link} or %{support_link}."
+msgstr ""
+
+msgid "AdminUsers|Important information about usage on your GitLab instance"
+msgstr ""
+
 msgid "AdminUsers|Is using seat"
 msgstr ""
 
@@ -2399,6 +2411,9 @@ msgstr ""
 msgid "AdminUsers|Log in"
 msgstr ""
 
+msgid "AdminUsers|Manage (accept/reject) pending user sign ups"
+msgstr ""
+
 msgid "AdminUsers|New user"
 msgstr ""
 
@@ -2498,6 +2513,18 @@ msgstr ""
 msgid "AdminUsers|Users"
 msgstr ""
 
+msgid "AdminUsers|Users can still be invited to your instance and/or add themselves if permitted based on your settings. They will not have access to your instance, nor count towards your subscribed seat count until you %{approve_link}."
+msgstr ""
+
+msgid "AdminUsers|View pending member requests"
+msgstr ""
+
+msgid "AdminUsers|What can I do?"
+msgstr ""
+
+msgid "AdminUsers|What does this mean?"
+msgstr ""
+
 msgid "AdminUsers|When the user logs back in, their account will reactivate as a fully active account"
 msgstr ""
 
@@ -2531,6 +2558,21 @@ msgstr ""
 msgid "AdminUsers|You must transfer ownership or delete the groups owned by this user before you can delete their account"
 msgstr ""
 
+msgid "AdminUsers|Your GitLab instance has reached the maximum allowed %{user_doc_link} set by an instance admin."
+msgstr ""
+
+msgid "AdminUsers|approve them"
+msgstr ""
+
+msgid "AdminUsers|contact our support team"
+msgstr ""
+
+msgid "AdminUsers|docs"
+msgstr ""
+
+msgid "AdminUsers|user cap"
+msgstr ""
+
 msgid "Administration"
 msgstr ""