EDIT: Checked, this config should work:
- module: haproxy
# All logs
log:
enabled: true
# Set which input to use between syslog (default) or file.
#var.input:
var.input: "file"
# Set custom paths for the log files. If left empty,
# Filebeat will choose the paths depending on your OS.
var.paths: ["/var/log/haproxy.log"]
input:
processors:
- add_tags:
tags: [test]
The key was the missing input parent field. The post you mentioned was misleading in this aspect. I have edited already