Updating index settings through API.

initial-settings.json

{
  "index": {
    "analysis": {
      "analyzer": {
        "fulltext_analyzer": {
          "char_filter": "html_strip", 
          "filter": [
            "asciifolding", 
            "fulltext_word_delimiter_filter", 
            "lowercase", 
            "synonym_filter", 
            "snowball"
          ], 
          "tokenizer": "whitespace", 
          "type": "custom"
        }
      }, 
      "filter": {
        "fulltext_word_delimiter_filter": {
          "catenate_all": false, 
          "catenate_words": true, 
          "generate_number_parts": true, 
          "generate_word_parts": true, 
          "preserve_original": false, 
          "split_on_case_change": true, 
          "split_on_numerics": true, 
          "stem_english_possessive": true, 
          "type": "word_delimiter"
        }, 
        "synonym_filter": {
          "synonyms": [
            "synonym definition 1",
            "synonym definition 2"
          ], 
          "type": "synonym"
        }
      }
    }
  }
}

settings-after-initial.json

{
  "test" : {
    "settings" : {
      "index.number_of_replicas" : "1",
      "index.analysis.filter.fulltext_word_delimiter_filter.generate_word_parts" : "true",
      "index.analysis.analyzer.fulltext_analyzer.filter.0" : "asciifolding",
      "index.analysis.filter.synonym_filter.synonyms.0" : "synonym definition 1",
      "index.analysis.filter.fulltext_word_delimiter_filter.catenate_all" : "false",
      "index.analysis.analyzer.fulltext_analyzer.tokenizer" : "whitespace",
      "index.analysis.analyzer.fulltext_analyzer.filter.4" : "snowball",
      "index.analysis.filter.fulltext_word_delimiter_filter.catenate_words" : "true",
      "index.analysis.filter.synonym_filter.synonyms.1" : "synonym definition 2",
      "index.analysis.analyzer.fulltext_analyzer.char_filter" : "html_strip",
      "index.analysis.analyzer.fulltext_analyzer.filter.3" : "synonym_filter",
      "index.analysis.filter.synonym_filter.type" : "synonym",
      "index.analysis.filter.fulltext_word_delimiter_filter.type" : "word_delimiter",
      "index.analysis.analyzer.fulltext_analyzer.filter.2" : "lowercase",
      "index.analysis.filter.fulltext_word_delimiter_filter.preserve_original" : "false",
      "index.analysis.analyzer.fulltext_analyzer.type" : "custom",
      "index.analysis.analyzer.fulltext_analyzer.filter.1" : "fulltext_word_delimiter_filter",
      "index.version.created" : "191199",
      "index.analysis.filter.fulltext_word_delimiter_filter.generate_number_parts" : "true",
      "index.analysis.filter.fulltext_word_delimiter_filter.split_on_case_change" : "true",
      "index.analysis.filter.fulltext_word_delimiter_filter.split_on_numerics" : "true",
      "index.analysis.filter.fulltext_word_delimiter_filter.stem_english_possessive" : "true",
      "index.number_of_shards" : "5"
    }
  }
}

settings-after-update.json

{
  "test" : {
    "settings" : {
      "index.number_of_replicas" : "1",
      "index.analysis.filter.fulltext_word_delimiter_filter.generate_word_parts" : "true",
      "index.analysis.analyzer.fulltext_analyzer.filter.0" : "asciifolding",
      "index.analysis.filter.synonym_filter.synonyms.0" : "synonym definition 1",
      "index.analysis.filter.fulltext_word_delimiter_filter.catenate_all" : "false",
      "index.analysis.analyzer.fulltext_analyzer.tokenizer" : "whitespace",
      "index.analysis.analyzer.fulltext_analyzer.filter.4" : "snowball",
      "index.analysis.filter.fulltext_word_delimiter_filter.catenate_words" : "true",
      "index.analysis.filter.synonym_filter.synonyms.1" : "synonym definition 2",
      "index.analysis.analyzer.fulltext_analyzer.char_filter" : "html_strip",
      "index.analysis.analyzer.fulltext_analyzer.filter.3" : "synonym_filter",
      "index.analysis.filter.synonym_filter.type" : "synonym",
      "index.analysis.filter.fulltext_word_delimiter_filter.type" : "word_delimiter",
      "index.analysis.analyzer.fulltext_analyzer.filter.2" : "lowercase",
      "index.analysis.filter.fulltext_word_delimiter_filter.preserve_original" : "false",
      "index.analysis.analyzer.fulltext_analyzer.type" : "custom",
      "index.analysis.analyzer.fulltext_analyzer.filter.1" : "fulltext_word_delimiter_filter",
      "index.version.created" : "191199",
      "index.analysis.filter.fulltext_word_delimiter_filter.generate_number_parts" : "true",
      "index.analysis.filter.fulltext_word_delimiter_filter.split_on_case_change" : "true",
      "index.analysis.filter.fulltext_word_delimiter_filter.split_on_numerics" : "true",
      "index.analysis.filter.fulltext_word_delimiter_filter.stem_english_possessive" : "true",
      "index.number_of_shards" : "5"
    }
  }
}

settings-update.json

{
  "index": {
    "analysis": {
      "analyzer": {
        "fulltext_analyzer": {
          "char_filter": "html_strip", 
          "filter": [
            "asciifolding", 
            "fulltext_word_delimiter_filter", 
            "lowercase", 
            "synonym_filter", 
            "snowball"
          ], 
          "tokenizer": "whitespace", 
          "type": "custom"
        }
      }, 
      "filter": {
        "fulltext_word_delimiter_filter": {
          "catenate_all": false, 
          "catenate_words": true, 
          "generate_number_parts": true, 
          "generate_word_parts": true, 
          "preserve_original": false, 
          "split_on_case_change": true, 
          "split_on_numerics": true, 
          "stem_english_possessive": true, 
          "type": "word_delimiter"
        }, 
        "synonym_filter": {
          "synonyms": [
            "synonym definition 1",
            "synonym definition 2"
          ], 
          "type": "synonym"
        }
      }
    }
  }
}