[BUG] Reporting CSV does not work when indices is in remote cluster

[penghuo]

What is the bug? Reporting CSV does not work when indices is in remote cluster

Why reporting failed? Reporting required mapping and setting of index to generate CSV file. But cross cluster search feature does not support it for now. For example,

curl -XGET "http://localhost:9200/testremote:test_00001"

{
  "error" : {
    "root_cause" : [
      {
        "type" : "index_not_found_exception",
        "reason" : "no such index [testremote:test_00001]",
        "index" : "testremote:test_00001",
        "resource.id" : "testremote:test_00001",
        "resource.type" : "index_or_alias",
        "index_uuid" : "_na_"
      }
    ],
    "type" : "index_not_found_exception",
    "reason" : "no such index [testremote:test_00001]",
    "index" : "testremote:test_00001",
    "resource.id" : "testremote:test_00001",
    "resource.type" : "index_or_alias",
    "index_uuid" : "_na_"
  },
  "status" : 404
}

Why OSD index pattern works? OSD index pattern creation Field capabilities API to fetch fields and types, which is supported by cross cluster search.

POST /testremote:test_00001/_field_caps?fields=*