Hi All
Here is my output conf file, i am not able to post data to endpoint
output {
    http {
      url => "https://abcd.com/dataEventRequests"
         http_method => "post"
         content_type => "application/vnd.abcd.resourceitem+json"
         headers => {
   "Authorization" => "Basic SENNX0lNUEw6SnJvOTg0ODM="
   "Host" => "abcd.com:443"
   "Accept-Encoding" => "gzip,deflate"
   "Content-Length" => "292"
         }
         format => "json"
   message =>'{"sourceId":"ABCD_EFG","requestNumber":"1234","requestTimestamp":"2017-01-12T08:00:00.000-08:00"}'
    }
    }
My output is in JSON format, i checked in SOAP UI it is working well.
Here is the error that you get in log file
[2017-01-13T17:51:54,686][ERROR][logstash.outputs.http ] [HTTP Output Failure] Could not fetch URL {:url=>"https://abcd.com/dataEventRequests",..........................
Again this working well for me in the SOAP UI using REST projects