Proper way to upload a doc to FSCrawler for indexing in Elasticsearch

I'm prototyping a Rails application to upload documents to FSCrawler (running the REST interface), to incorporate into an Elasticsearch index. Using their example, this works:

response = `curl -F "file=@#{params[:document][:upload].tempfile.path}" "http://127.0.0.1:8080/fscrawler/_upload?debug=true"`

The file gets uploaded, and the content gets indexed. This is an example of what I get:

"{\n \"ok\" : true,\n \"filename\" : \"RackMultipart20200130-91061-16swulg.pdf\",\n \"url\" : \"http://127.0.0.1:9200/local/_doc/d661edecf3e28572676e97a6f0d1d\",\n \"doc\" : {\n \"content\" : \"\\n \\n \\n\\nBasically, what you need to know is that Dante is all IP-based, and makes use of common IT standards. Each Dante device behaves \\n\\nmuch like any other network device you would already find on your network. \\n\\nIn order to make integration into an existing network easy, here are some of the things that Dante does: \\n\\n▪ Dante...

When I run curl at the command line, I get EVERYTHING, like the "filename" being properly set. If I use it as above, in the Rails controller, as you can see, the filename is set to the Tempfile's filename. That's not a workable solution. Trying to use params[:document][:upload].tempfile (without .path) or just params[:document][:upload] both fail entirely.

I'm trying to do this "the right way," but every incarnation of using a proper HTTP client to do this fails. I can't figure out how to invoke an HTTP POST that will submit a file to FSCrawler the way curl (on the command line) does it.

In this example, I'm just trying to send the file by using the Tempfile file object. For some reason, FSCrawler gives me the error in the comment, and get a little metadata, but no content is indexed:

## Failed to extract [100000] characters of text for ...
## org.apache.tika.exception.ZeroByteFileException: InputStream must have > 0 bytes
uri = URI("http://127.0.0.1:8080/fscrawler/_upload?debug=true")
request = Net::HTTP::Post.new(uri)
form_data = [['file', params[:document][:upload].tempfile,
  { filename: params[:document][:upload].original_filename,
  content_type: params[:document][:upload].content_type }]]
request.set_form form_data, 'multipart/form-data'
response = Net::HTTP.start(uri.hostname, uri.port) do |http|
  http.request(request)
end

If I change the above to use params[:document][:upload].tempfile.path, then I don't get the error about the InputStream, but I also (still) do not get any content indexed. This is an example of what I get:

 {"_index":"local","_type":"_doc","_id":"72c9ecf2a83440994eb87d28786e6","_version":3,"_seq_no":26,"_primary_term":1,"found":true,"_source":{"content":"/var/folders/bn/pcc1h8p16tl534pw__fdz2sw0000gn/T/RackMultipart20200130-91061-134tcxn.pdf\n","meta":{},"file":{"extension":"pdf","content_type":"text/plain; charset=ISO-8859-1","indexing_date":"2020-01-30T15:33:45.481+0000","filename":"Similarity in Postgres and Rails using Trigrams · pganalyze.pdf"},"path":{"virtual":"Similarity in Postgres and Rails using Trigrams · pganalyze.pdf","real":"Similarity in Postgres and Rails using Trigrams · pganalyze.pdf"}}}

If I try to use RestClient, and I try send the file by referencing the actual path to the Tempfile, then I get this error message, and I get nothing:

## Unsupported media type
response = RestClient.post 'http://127.0.0.1:8080/fscrawler/_upload?debug=true',
  file: params[:document][:upload].tempfile.path,
  content_type: params[:document][:upload].content_type

If I try to .read() the file, and submit that, then I break the FSCrawler form:

## Internal server error
request = RestClient::Request.new(
  :method => :post,
  :url => 'http://127.0.0.1:8080/fscrawler/_upload?debug=true',
  :payload => {
    :multipart => true,
    :file => File.read(params[:document][:upload].tempfile),
    :content_type => params[:document][:upload].content_type
})
response = request.execute

Obviously, I've been trying this every way I can, but I can't replicate whatever curl is doing with any known Ruby-based HTTP clients. I'm utterly lost as to how to get Ruby to submit data to FSCrawler in a way that will get the document contents indexed properly. I've been at this far longer than I care to admit. What am I missing here?

I finally tried Faraday, and, based on this answer, came up with the following:

connection = Faraday.new('http://127.0.0.1:8080') do |f|
  f.request :multipart
  f.request :url_encoded
  f.adapter :net_http
end
file = Faraday::UploadIO.new(
  params[:document][:upload].tempfile.path,
  params[:document][:upload].content_type,
  params[:document][:upload].original_filename
)
payload = { :file => file }
response = connection.post('/fscrawler/_upload', payload)

Using Fiddler helped me to see the results of my attempts, as I got closer and closer to the curl request. This snippet posts the request almost exactly as curl does. To route this call through the proxy, I just needed to add , proxy: 'http://localhost:8866' to the end of the connection setup.