Remove old Advanced Search migrations

Changelog: changed
EE: true

doc/development/elasticsearch.md

@@ -308,7 +308,8 @@ We choose to use GitLab major version upgrades as a safe time to remove
 backwards compatibility for indices that have not been fully migrated. We
 [document this in our upgrade
 documentation](../update/index.md#upgrading-to-a-new-major-version). We also
-choose to remove the migration code and tests so that:
+choose to remove the migration code by replacing it with the halted migration
+and remove tests so that:
 
 - We don't need to maintain any code that is called from our Advanced Search
   migrations.
@@ -334,18 +335,10 @@ For every migration that was created 2 minor versions before the major version
 being upgraded to, we do the following:
 
 1. Confirm the migration has actually completed successfully for GitLab.com.
-1. Replace the content of `migrate` and `completed?` methods as follows:
+1. Replace the content of the migration with:
 
    ```ruby
-   def migrate
-     log_raise "Migration has been deleted in the last major version upgrade." \
-       "Migrations are supposed to be finished before upgrading major version https://docs.gitlab.com/ee/update/#upgrading-to-a-new-major-version ." \
-       "To correct this issue, recreate your index from scratch: https://docs.gitlab.com/ee/integration/elasticsearch.html#last-resort-to-recreate-an-index."
-   end
-
-   def completed?
-     false
-   end
+   include Elastic::MigrationObsolete
    ```
 
 1. Delete any spec files to support this migration.

ee/app/models/elastic/migration_record.rb

@@ -4,7 +4,9 @@ module Elastic
   class MigrationRecord
     attr_reader :version, :name, :filename
 
-    delegate :migrate, :skip_migration?, :completed?, :batched?, :throttle_delay, :pause_indexing?, :space_requirements?, :space_required_bytes, to: :migration
+    delegate :migrate, :skip_migration?, :completed?, :batched?, :throttle_delay, :pause_indexing?,
+      :space_requirements?, :space_required_bytes, :obsolete?,
+      to: :migration
 
     ELASTICSEARCH_SIZE = 25
 

ee/app/services/elastic/data_migration_service.rb

@@ -29,6 +29,15 @@ module Elastic
         migrations.find { |migration| migration.name_for_key == name.to_s.underscore }
       end
 
+      def find_by_name!(name)
+        migration = find_by_name(name)
+
+        raise ArgumentError, "Couldn't find Elastic::Migration with name='#{name}'" unless migration
+        raise ArgumentError, "Elastic::Migration with name='#{name}' is marked as obsolete" if migration.obsolete?
+
+        migration
+      end
+
       def drop_migration_has_finished_cache!(migration)
         Rails.cache.delete cache_key(:migration_has_finished, migration.name_for_key)
       end

ee/app/workers/concerns/elastic/migration_obsolete.rb

+# frozen_string_literal: true
+
+module Elastic
+  module MigrationObsolete
+    def migrate
+      log "Migration has been deleted in the last major version upgrade." \
+        "Migrations are supposed to be finished before upgrading major version https://docs.gitlab.com/ee/update/#upgrading-to-a-new-major-version ." \
+        "To correct this issue, recreate your index from scratch: https://docs.gitlab.com/ee/integration/elasticsearch.html#last-resort-to-recreate-an-index."
+
+      fail_migration_halt_error!
+    end
+
+    def completed?
+      false
+    end
+
+    def obsolete?
+      true
+    end
+  end
+end

ee/elastic/migrate/20201105181100_apply_max_analyzed_offset.rb

 # frozen_string_literal: true
 
 class ApplyMaxAnalyzedOffset < Elastic::Migration
-  # Important: Any update to the Elastic index mappings should be replicated in Elastic::Latest::Config
-
-  def migrate
-    if max_analyzed_offset_setting == current_max_analyzed_offset
-      log "Skipping highlight.max_analyzed_offset migration since it is already applied"
-      return
-    end
-
-    log "Setting highlight.max_analyzed_offset to #{max_analyzed_offset_setting}kb"
-    helper.update_settings(settings: { index: { 'highlight.max_analyzed_offset': max_analyzed_offset_setting } })
-    log 'Update of highlight.max_analyzed_offset is completed'
-  end
-
-  # Check if the migration has completed
-  # Return true if completed, otherwise return false
-  def completed?
-    max_analyzed_offset_setting == current_max_analyzed_offset
-  end
-
-  private
-
-  def max_analyzed_offset_setting
-    Gitlab::CurrentSettings.elasticsearch_indexed_file_size_limit_kb.kilobytes
-  end
-
-  def current_max_analyzed_offset
-    Gitlab::Elastic::Helper.default.get_settings.dig('highlight', 'max_analyzed_offset').to_i
-  end
+  include Elastic::MigrationObsolete
 end

ee/lib/elastic/migration.rb

@@ -23,6 +23,10 @@ module Elastic
       raise NotImplementedError, 'Please extend Elastic::Migration'
     end
 
+    def obsolete?
+      false
+    end
+
     private
 
     def helper

ee/spec/support/helpers/elasticsearch_helpers.rb

@@ -43,7 +43,7 @@ module ElasticsearchHelpers
     version = if name_or_version.is_a?(Numeric)
                 name_or_version
               else
-                Elastic::DataMigrationService.find_by_name(name_or_version).version
+                Elastic::DataMigrationService.find_by_name!(name_or_version).version
               end
 
     Elastic::DataMigrationService.migrations.each do |migration|

ee/spec/workers/concerns/elastic/migration_obsolete_spec.rb

+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+
+RSpec.describe Elastic::MigrationObsolete do
+  let(:migration_class) do
+    Class.new do
+      include Elastic::MigrationObsolete
+    end
+  end
+
+  subject { migration_class.new }
+
+  describe '#migrate' do
+    it 'logs a message and halts the migration' do
+      expect(subject).to receive(:log).with(/has been deleted in the last major version upgrade/)
+      expect(subject).to receive(:fail_migration_halt_error!).and_return(true)
+
+      subject.migrate
+    end
+  end
+
+  describe '#completed?' do
+    it 'returns false' do
+      expect(subject.completed?).to be false
+    end
+  end
+
+  describe '#obsolete?' do
+    it 'returns true' do
+      expect(subject.obsolete?).to be true
+    end
+  end
+end