Allow 0 for max_pages_size as infinity

app/models/application_setting.rb

@@ -137,7 +137,7 @@ class ApplicationSetting < ApplicationRecord
 
   validates :max_pages_size,
             presence: true,
-            numericality: { only_integer: true, greater_than: 0,
+            numericality: { only_integer: true, greater_than_or_equal_to: 0,
                             less_than: ::Gitlab::Pages::MAX_SIZE / 1.megabyte }
 
   validates :default_artifacts_expire_in, presence: true, duration: true

changelogs/unreleased/199422-maximum-size-for-gitlab-pages-says-to-set-it-to-0-for-unlimited-bu.yml

+---
+title: Allow 0 for pages size limit setting in admin settings
+merge_request: 28086
+author:
+type: fixed

spec/models/application_setting_spec.rb

@@ -69,12 +69,12 @@ describe ApplicationSetting do
 
     it { is_expected.to validate_numericality_of(:snippet_size_limit).only_integer.is_greater_than(0) }
     it { is_expected.to validate_presence_of(:max_artifacts_size) }
-    it do
-      is_expected.to validate_numericality_of(:max_pages_size).only_integer.is_greater_than(0)
+    it { is_expected.to validate_numericality_of(:max_artifacts_size).only_integer.is_greater_than(0) }
+    it { is_expected.to validate_presence_of(:max_pages_size) }
+    it 'ensures max_pages_size is an integer greater than 0 (or equal to 0 to indicate unlimited/maximum)' do
+      is_expected.to validate_numericality_of(:max_pages_size).only_integer.is_greater_than_or_equal_to(0)
                        .is_less_than(::Gitlab::Pages::MAX_SIZE / 1.megabyte)
     end
-    it { is_expected.to validate_numericality_of(:max_artifacts_size).only_integer.is_greater_than(0) }
-    it { is_expected.to validate_numericality_of(:max_pages_size).only_integer.is_greater_than(0) }
 
     it { is_expected.not_to allow_value(7).for(:minimum_password_length) }
     it { is_expected.not_to allow_value(129).for(:minimum_password_length) }