Regex parses incorrectly in yml vs. conf file

[jregovic]

Bug Report

Describe the bug
When attempting to convert a parser file from the legacy "conf" method to YAML, I receive an error when using the example from https://github.com/fluent/fluent-bit/blob/master/conf/parsers.conf. Specifically, the istio-envoy-proxy regex produces an error.

To Reproduce
https://rubular.com/r/17KGEdDClwiuDG

[2025/01/09 20:24:19] [error] [parser:istio-envoy-proxy] Invalid regex pattern ^\[(?<start_time>[^\]]*)\] "(?<method>\S+)(?: +(?<path>[^\"]*?)(?: +\S*)?)? (?<protocol>\S+)" (?<response_code>[^ ]*) (?<response_flags>[^ ]*) (?<response_code_details>[^ ]*) (?<connection_termination_details>[^ ]*) (?<upstream_transport_failure_reason>[^ ]*) (?<bytes_received>[^ ]*) (?<bytes_sent>[^ ]*) (?<duration>[^ ]*) (?<x_envoy_upstream_service_time>[^ ]*) "(?<x_forwarded_for>[^ ]*)" "(?<user_agent>[^\"]*)" "(?<x_request_id>[^\"]*)" (?<authority>[^ ]*)" "(?<upstream_host>[^ ]*)" (?<upstream_cluster>[^ ]*) (?<upstream_local_address>[^ ]*) (?<downstream_local_address>[^ ]*) (?<downstream_remote_address>[^ ]*) (?<requested_server_- name:>[^ ]*) (?<route_- name:>[^  ]*)

• Steps to reproduce the problem:

1. convert the parsers.conf file to YAML
2. run the fluent-bit

Expected behavior
No Errors

Your Environment

• Version used: 3.2.4c

• Configuration: parsers.yml.gz

• Operating System and version: Ubuntu 24.04

• Filters and plugins: