How to fix(remove) a "bad" index settings update?

Elastic Stack Elasticsearch
1

I made an "Index _settings update" by doing the following:

  1. POST to /index/_close
  2. PUT to /index/_settings
  3. POST to /index/_open

The server gave me an "error" in the log since the format was wrong - but it also saved the update, thereby corrupting the index settings in an "irreversible" way.

The only option at this point would be - create new index, fix existing index setting until we can "open" it again, and then bulk api copy it to a new index.

Are there ways for "recovering' from the situation other than recreating the index? (Especially if the said analyzers are not yet in use?)

P.S. Purpose is to learn - since in this case, i have mostly test data where losing is a pain - but not end of the world. Doing this on production would be bad!

Details follow:

Settings update:

{
  "analysis": {
    "filter": {
      "synonym": {
        "type": "synonym",
        "format": "wordnet",
        "synonyms_path": "analysis/wn_s.pl"
      },
      "ascii_folding": {
        "type": "asciifolding"
      },
    "analyzer": {
      "fulltext_analyzer": {
        "type": "custom",
        "tokenizer": "standard",
        "filter": [
          "lowercase",
          "word_delimiter",
          "synonym"
        ]
      }
    }
    }
  }
}

So far so good. But on closer look, I messed up - I added "analyzer" under "filter".
And the error was:

 org.elasticsearch.ElasticsearchIllegalArgumentException: token filter [analyzer] must have a type associated with it

But the problem is - now I can't 'remove' the entry of 'analyzer'. my only option is to add 'type: standard' and live with the corrupted setting in the index.

The following would have helped avoid the situation:

  • The docs could warn that most "settings API updates" are irreversible (You can only "add" a new dictionary but never remove - even new fields would only "merge the fields" with existing fields)
  • With server-side validation of the JSON - or just not save if the
    settings API had an 'error'