The keyword analyzer is a “noop” analyzer which returns the entire input
string as a single token.
POST _analyze
{
  "analyzer": "keyword",
  "text": "The 2 QUICK Brown-Foxes jumped over the lazy dog's bone."
}The above sentence would produce the following single term:
[ The 2 QUICK Brown-Foxes jumped over the lazy dog's bone. ]
The keyword analyzer is not configurable.
The keyword analyzer consists of:
If you need to customize the keyword analyzer then you need to
recreate it as a custom analyzer and modify it, usually by adding
token filters. Usually, you should prefer the
Keyword type when you want strings that are not split
into tokens, but just in case you need it, this would recreate the
built-in keyword analyzer and you can use it as a starting point
for further customization: