Drop kibana_hostname column

app/models/clusters/applications/elastic_stack.rb

@@ -16,7 +16,7 @@ module Clusters
       include ::Gitlab::Utils::StrongMemoize
 
       include IgnorableColumns
-      ignore_column :kibana_hostname, remove_with: '12.8', remove_after: '2020-01-22'
+      ignore_column :kibana_hostname, remove_with: '12.9', remove_after: '2020-02-22'
 
       default_value_for :version, VERSION
 

changelogs/unreleased/ak-migration-cleanu.yml

+---
+title: Remove kibana_hostname column from clusters_applications_elastic_stacks table
+merge_request: 23503
+author:
+type: changed

db/post_migrate/20200122144759_drop_kibana_column.rb

+# frozen_string_literal: true
+
+class DropKibanaColumn < ActiveRecord::Migration[5.2]
+  DOWNTIME = false
+
+  def change
+    remove_column :clusters_applications_elastic_stacks, :kibana_hostname, :string, limit: 255
+  end
+end

db/schema.rb

@@ -1150,7 +1150,6 @@ ActiveRecord::Schema.define(version: 2020_01_27_090233) do
     t.bigint "cluster_id", null: false
     t.integer "status", null: false
     t.string "version", limit: 255, null: false
-    t.string "kibana_hostname", limit: 255
     t.text "status_reason"
     t.index ["cluster_id"], name: "index_clusters_applications_elastic_stacks_on_cluster_id", unique: true
   end