Cant send logs via Filebeat using Reverse proxy endpoint for Elasticsearch server

[aparasxidis (Alonso Parasxidis Moreno)]

Hi, I'm running Filebeat on a EC2 machine as a docker container and configured to get logs from a Jenkins container, the Elasticsearch server is on another EC2 machine behind a reverse proxy (nginx), I can curl to the Elasticsearch using the URL or IP from the Filebeat machine, this is my filebeat.yml

filebeat.inputs:
- type: log
  enabled: true
  paths:
    - /var/jenkins_home/logs/*.log.*
  multiline.pattern: '^[A-Z]{1}[a-z]{2} {1,2}[0-9]{1,2}, [0-9]{4} {1,2}[0-9]{1,2}:[0-9]{2}:[0-9]{2}'
  multiline.negate: true
  multiline.match: after

output.elasticsearch:
  hosts: ["http://xxxxx.xxxxx.com/elastic"]
  username: elastic
  password: somepassword
  timeout: 120

  path: "/elastic"
  proxy_url: http://xxxxxx.xxxxx.com

I don't know how to configure the host field, should I use the URL or IP, or what/how to specify in the proxy_url field, right now my elastic is reachable from:
URL
http://xxxxx.xxxxx.com/elastic
http://xxxxx.xxxxx.com/9200

IP
http://xx.xxx.xxx.xxx/elastic
http://xx.xxx.xxx.xxx/9200

This is the error I'm getting in the logs from Filebeat:

ERROR   pipeline/output.go:100  Failed to connect to backoff(elasticsearch(http://xx.xxx.xxx.xxx:9200/elastic)): Get http://xx.xxx.xxx.xxx:9200/elastic: net/http: request canceled while waiting for connection (Client.Timeout exceeded while awaiting headers)