How to use OCR in Elasticsearch ingest attachment plugin?

Elastic Stack Elasticsearch
11

I liked the simulate API approach, I got it to work via curl :

curl -F "file=@pdf_files/non-searchable-text.pdf" "http://127.0.0.1:8080/fscrawler/_upload?debug=true&simulate=true"

Which gave me this response :

{
  "ok": true,
  "filename": "non-searchable-text.pdf",
  "url": "http://127.0.0.1:9200/resumes/_doc/f39614d4716aed76167498ac4945ed7",
  "doc": {
    "content": "\n \n\nTABLE OF CONTENTS\n\n \n\nIntroduction 1\nChapter 1: The ABC of Programming 11\nChapter 2: Basic JavaScript Instructions 53\nChapter 3: Functions, Methods & Objects 85\n(i aY-] 0) (=) ae Sam DY -101 |} (0) aioe\" Mole) 0-) 145\nChapter 5: Document Object Model 183\nChapter 6: Events 243\nChapter 7: jQuery 293\nChapter 8: Ajax & JSON 367\nChapter 9: APIs 409\nChapter 10: Error Handling & Debugging 449\nChapter 11: Content Panels 487\nChapter 12: Filtering, Searching & Sorting 527\nChapter 13: Form Enhancement & Validation 567\nTare toy 623\n\n \n\nTry out & download the code in this book\nwww. javascriptbook.com\n\n \n\n \n\n \n\n\n",
    "meta": {
      "date": "2021-02-02T11:44:56.000+00:00",
      "format": "application/pdf; version=1.6"
    },
    "file": {
      "extension": "pdf",
      "content_type": "application/pdf",
      "indexing_date": "2021-02-04T13:49:29.353+00:00",
      "filename": "non-searchable-text.pdf"
    },
    "path": {
      "virtual": "non-searchable-text.pdf",
      "real": "non-searchable-text.pdf"
    }
  }
}

I tried making it work through PHP like this :

$curl = curl_init();

curl_setopt($curl, CURLOPT_URL, 'http://127.0.0.1:8080/fscrawler/_upload?debug=true&simulate=true');
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl, CURLOPT_POST, 1);
$args['file'] = '@/pdf_files/non-searchable-text.pdf';
curl_setopt($curl, CURLOPT_POSTFIELDS, $args);

$result = curl_exec($curl);
if (curl_errno($curl)) {
    echo 'Error:' . curl_error($curl);
} else {
    echo '<pre> response : ', print_r($result, true) ,'</pre>';
}
curl_close($curl);

But this was the response :

curl response

Any idea what I'm doing wrong ?