Reindex behind an alias with no downtime

curl -XPOST localhost:9200/_reindex -H 'Content-Type: application/json' -d '
  {"source":{"index":"orders-v1"},"dest":{"index":"orders-v2"}}'

curl -XPOST localhost:9200/_aliases -H 'Content-Type: application/json' -d '
  {"actions":[
    {"remove":{"index":"orders-v1","alias":"orders"}},
    {"add":{"index":"orders-v2","alias":"orders"}}
  ]}'