Disallow `NULL` values for `geo_nodes.primary` column

db/post_migrate/20190618171120_update_geo_nodes_primary.rb

+# frozen_string_literal: true
+
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class UpdateGeoNodesPrimary < ActiveRecord::Migration[5.1]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    change_column_default(:geo_nodes, :primary, false)
+    change_column_null(:geo_nodes, :primary, false, false)
+  end
+
+  def down
+    change_column_default(:geo_nodes, :primary, nil)
+    change_column_null(:geo_nodes, :primary, true)
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20190613030606) do
+ActiveRecord::Schema.define(version: 20190618171120) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -1391,7 +1391,7 @@ ActiveRecord::Schema.define(version: 20190613030606) do
   end
 
   create_table "geo_nodes", id: :serial, force: :cascade do |t|
-    t.boolean "primary"
+    t.boolean "primary", default: false, null: false
     t.integer "oauth_application_id"
     t.boolean "enabled", default: true, null: false
     t.string "access_key"