How to uplaod a file to a multipart post request in ruby - ruby

Question

I am trying to upload a file(huge) to a multipart post request in ruby. I use the following code but it gives me 500 internal server error:
RestClient.post("urladdress',
:name_of_file_param => File.new('path_of_the_file_to_be_uploaded'))
Following is the multipart request from the endpoint I am using currently:
POST address HTTP/1.1
Host: ip address
Content-Length: 325
Cache-Control: max-age=0
Origin: http://address
Upgrade-Insecure-Requests: 1
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryol2BpbpZ9cZlqFyb
User-Agent: blah blah blah
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
Referer: http://address
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
------WebKitFormBoundaryol2BpbpZ9cZlqFyb
Content-Disposition: form-data; name="uploadedFile"; filename="blah.csv"
Content-Type: text/csv
123456789010290
123456789010290
------WebKitFormBoundaryol2BpbpZ9cZlqFyb
Content-Disposition: form-data; name="submit"
Upload APK
------WebKitFormBoundaryol2BpbpZ9cZlqFyb--
Also if someone can help me with creating a new endpoint which can be used to upload the file without using multipart that is fine too.
Thanks,
RV