_reindex merge using wildcard

_reindex_merge.txt

DELETE my_*

PUT _template/template_1
{
  "index_patterns": ["*"],
  "order": 1,
  "settings": {
    "number_of_shards": 1,
    "number_of_replicas": 0
  }
}

POST my_source_1/_doc
{
  "text": "from my_source_1"
}

POST my_source_2/_doc
{
  "text": "from my_source_2"
}

POST _reindex
{
  "source": {
    "index": "my_source*"
  },
  "dest": {
    "index": "my_dest"
  },
  "script": {
    "source": "ctx._id = ctx._index + ':' + ctx._id",
    "lang": "painless"
  }
}

GET my_dest/_search