4 files changed, 34 insertions, 3 deletions
diff --git a/lib/gitlab/ci/config/entry/default.rb b/lib/gitlab/ci/config/entry/default.rb
index eaaf9f69102..145772c7a92 100644
--- a/lib/gitlab/ci/config/entry/default.rb
+++ b/lib/gitlab/ci/config/entry/default.rb
@@ -53,7 +53,7 @@ module Gitlab
             description: 'Set retry default value.',
             inherit: false
 
-          entry :tags, ::Gitlab::Config::Entry::ArrayOfStrings,
+          entry :tags, Entry::Tags,
             description: 'Set the default tags.',
             inherit: false
 
diff --git a/lib/gitlab/ci/config/entry/job.rb b/lib/gitlab/ci/config/entry/job.rb
index bd4d5f33689..f867189d521 100644
--- a/lib/gitlab/ci/config/entry/job.rb
+++ b/lib/gitlab/ci/config/entry/job.rb
@@ -85,7 +85,7 @@ module Gitlab
             description: 'Retry configuration for this job.',
             inherit: true
 
-          entry :tags, ::Gitlab::Config::Entry::ArrayOfStrings,
+          entry :tags, Entry::Tags,
             description: 'Set the tags.',
             inherit: true
 
diff --git a/lib/gitlab/ci/config/entry/processable.rb b/lib/gitlab/ci/config/entry/processable.rb
index 3543b5493bd..2549c35ebd6 100644
--- a/lib/gitlab/ci/config/entry/processable.rb
+++ b/lib/gitlab/ci/config/entry/processable.rb
@@ -16,6 +16,7 @@ module Gitlab
 
           PROCESSABLE_ALLOWED_KEYS = %i[extends stage only except rules variables
                                         inherit allow_failure when needs resource_group].freeze
+          MAX_NESTING_LEVEL = 10
 
           included do
             validations do
@@ -31,7 +32,7 @@ module Gitlab
 
               with_options allow_nil: true do
                 validates :extends, array_of_strings_or_string: true
-                validates :rules, nested_array_of_hashes: true
+                validates :rules, nested_array_of_hashes_or_arrays: { max_level: MAX_NESTING_LEVEL }
                 validates :resource_group, type: String
               end
             end
diff --git a/lib/gitlab/ci/config/entry/tags.rb b/lib/gitlab/ci/config/entry/tags.rb
new file mode 100644
index 00000000000..ca3b48372e2
--- /dev/null
+++ b/lib/gitlab/ci/config/entry/tags.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    class Config
+      module Entry
+        ##
+        # Entry that represents an array of tags.
+        #
+        class Tags < ::Gitlab::Config::Entry::Node
+          include ::Gitlab::Config::Entry::Validatable
+
+          TAGS_LIMIT = 50
+
+          validations do
+            validates :config, array_of_strings: true
+
+            validate do
+              next unless ::Feature.enabled?(:ci_build_tags_limit, default_enabled: :yaml)
+
+              if config.is_a?(Array) && config.size >= TAGS_LIMIT
+                errors.add(:config, _("must be less than the limit of %{tag_limit} tags") % { tag_limit: TAGS_LIMIT })
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end