Merge branch '24059-round-robin-repository-storage' into 'master'

Resolve "Introduce round-robin project creation to spread load over multiple shards"

Allow multiple shards to be enabled in the admin settings page, balancing project creation across all enabled shards.

* `f.select ..., multiple: true` isn't the most beautiful UI in the world, but switching to `collection_check_boxes` (or a facsimile thereof) isn't trivial
* Should `pick_repository_storage` be a method of `ApplicationSetting`, or `Project`? It's going to accrete logic over time so perhaps it should be its own class already?
* This is written to avoid the need for a database migration, so it is`serialize :repository_storage` without `, Array`. This is tested, but alternatives include:
  * Add a database migration
  * Write a custom Coder that will accept a String or Array in `load` and always `dump an Array.

Closes #24059

See merge request !7273

Signed-off-by: Rémy Coutable <remy@rymai.me>

5 files changed, 41 insertions, 10 deletions

diff --git a/app/controllers/admin/application_settings_controller.rb b/app/controllers/admin/application_settings_controller.rb
index 6ef7cf0bae6..86e808314f4 100644
--- a/app/controllers/admin/application_settings_controller.rb
+++ b/app/controllers/admin/application_settings_controller.rb
@@ -116,8 +116,8 @@ class Admin::ApplicationSettingsController < Admin::ApplicationController
       :metrics_packet_size,
       :send_user_confirmation_email,
       :container_registry_token_expire_delay,
-      :repository_storage,
       :enabled_git_access_protocol,
+      repository_storages: [],
       restricted_visibility_levels: [],
       import_sources: [],
       disabled_oauth_sign_in_sources: []
diff --git a/app/helpers/application_settings_helper.rb b/app/helpers/application_settings_helper.rb
index 6229384817b..45a567a1eba 100644
--- a/app/helpers/application_settings_helper.rb
+++ b/app/helpers/application_settings_helper.rb
@@ -93,11 +93,11 @@ module ApplicationSettingsHelper
     end
   end
 
-  def repository_storage_options_for_select
+  def repository_storages_options_for_select
     options = Gitlab.config.repositories.storages.map do |name, path|
       ["#{name} - #{path}", name]
     end
 
-    options_for_select(options, @application_setting.repository_storage)
+    options_for_select(options, @application_setting.repository_storages)
   end
 end
diff --git a/app/models/application_setting.rb b/app/models/application_setting.rb
index c99aa7772bb..6e7a90e7d9c 100644
--- a/app/models/application_setting.rb
+++ b/app/models/application_setting.rb
@@ -18,6 +18,7 @@ class ApplicationSetting < ActiveRecord::Base
   serialize :disabled_oauth_sign_in_sources, Array
   serialize :domain_whitelist, Array
   serialize :domain_blacklist, Array
+  serialize :repository_storages
 
   cache_markdown_field :sign_in_text
   cache_markdown_field :help_page_text
@@ -74,9 +75,8 @@ class ApplicationSetting < ActiveRecord::Base
             presence: true,
             numericality: { only_integer: true, greater_than: 0 }
 
-  validates :repository_storage,
-    presence: true,
-    inclusion: { in: ->(_object) { Gitlab.config.repositories.storages.keys } }
+  validates :repository_storages, presence: true
+  validate :check_repository_storages
 
   validates :enabled_git_access_protocol,
             inclusion: { in: %w(ssh http), allow_blank: true, allow_nil: true }
@@ -166,7 +166,7 @@ class ApplicationSetting < ActiveRecord::Base
       disabled_oauth_sign_in_sources: [],
       send_user_confirmation_email: false,
       container_registry_token_expire_delay: 5,
-      repository_storage: 'default',
+      repository_storages: ['default'],
       user_default_external: false,
     )
   end
@@ -201,6 +201,29 @@ class ApplicationSetting < ActiveRecord::Base
     self.domain_blacklist_raw = file.read
   end
 
+  def repository_storages
+    value = read_attribute(:repository_storages)
+    value = [value] if value.is_a?(String)
+    value = [] if value.nil?
+
+    value
+  end
+
+  # repository_storage is still required in the API. Remove in 9.0
+  def repository_storage
+    repository_storages.first
+  end
+
+  def repository_storage=(value)
+    self.repository_storages = [value]
+  end
+
+  # Choose one of the available repository storage options. Currently all have
+  # equal weighting.
+  def pick_repository_storage
+    repository_storages.sample
+  end
+
   def runners_registration_token
     ensure_runners_registration_token!
   end
@@ -208,4 +231,12 @@ class ApplicationSetting < ActiveRecord::Base
   def health_check_access_token
     ensure_health_check_access_token!
   end
+
+  private
+
+  def check_repository_storages
+    invalid = repository_storages - Gitlab.config.repositories.storages.keys
+    errors.add(:repository_storages, "can't include: #{invalid.join(", ")}") unless
+      invalid.empty?
+  end
 end
diff --git a/app/models/project.rb b/app/models/project.rb
index 8d3eeea1e8b..e0062f3dbb4 100644
--- a/app/models/project.rb
+++ b/app/models/project.rb
@@ -28,7 +28,7 @@ class Project < ActiveRecord::Base
   default_value_for :archived, false
   default_value_for :visibility_level, gitlab_config_features.visibility_level
   default_value_for :container_registry_enabled, gitlab_config_features.container_registry
-  default_value_for(:repository_storage) { current_application_settings.repository_storage }
+  default_value_for(:repository_storage) { current_application_settings.pick_repository_storage }
   default_value_for(:shared_runners_enabled) { current_application_settings.shared_runners_enabled }
   default_value_for :issues_enabled, gitlab_config_features.issues
   default_value_for :merge_requests_enabled, gitlab_config_features.merge_requests
diff --git a/app/views/admin/application_settings/_form.html.haml b/app/views/admin/application_settings/_form.html.haml
index c4c68cd7891..28003e5f509 100644
--- a/app/views/admin/application_settings/_form.html.haml
+++ b/app/views/admin/application_settings/_form.html.haml
@@ -353,9 +353,9 @@
   %fieldset
     %legend Repository Storage
     .form-group
-      = f.label :repository_storage, 'Storage path for new projects', class: 'control-label col-sm-2'
+      = f.label :repository_storages, 'Storage paths for new projects', class: 'control-label col-sm-2'
       .col-sm-10
-        = f.select :repository_storage, repository_storage_options_for_select, {}, class: 'form-control'
+        = f.select :repository_storages, repository_storages_options_for_select, {include_hidden: false}, multiple: true, class: 'form-control'
         .help-block
           Manage repository storage paths. Learn more in the
           = succeed "." do