Can't parse plugins.conf anymore

[dlutz]

Bug Report

Describe the bug
Version 3.2.0 seems to have introduced a bug affecting parsing the file plugins.conf using the classic configuration. Parsing a file based on the example https://github.com/fluent/fluent-bit/blob/master/conf/plugins.conf doesn't work anymore.

Commit 6611a06 introduced the new function flb_plugin_load_config_format, which uses entry->key instead of entry->val->data.as_string (as in flb_plugin_load_config_file). fluent-bit then tries to load the plugin from the path path (i.e. the keyword path) instead of the effective path from the configuration.

To Reproduce

• Example log messages:

Dec 12 14:29:33 (redacted) fluent-bit[124779]: [2024/12/12 14:29:33] [error] [proxy] error opening plugin path: 'path: cannot open shared object file: No such file or directory'
Dec 12 14:29:33 (redacted) fluent-bit[124779]: [2024/12/12 14:29:33] [error] [plugin] error loading proxy plugin: path

• Steps to reproduce the problem:
  • Use classic configuration
  • Include plugins.conf from fluent-bit.conf (plugins_file plugins.conf)
  • Use plugins.conf like this (based on the example https://github.com/fluent/fluent-bit/blob/master/conf/plugins.conf)

[PLUGINS]
    # Path /path/to/out_gstdout.so
    Path /usr/local/lib/out_some_plugin.so

Expected behavior
The plugin should be loaded as before 3.2.0.

Screenshots
N/A

Your Environment

• Version used: 3.2.2
• Configuration: Classic configuration (with plugins.conf file)
• Environment name and version: VM based on Linux
• Operating System and version: RHEL 8.10
• Filters and plugins: Trying to use custom plugin

Additional context
Loading the plugin worked before 3.2.0. With 3.2.0, fluent-bit doesn't start but logs an error. (Loading the plugion with the -e command line option instead of using plugins.conf works.)

[Swaagie]

Can confirm, we ran into the same issue last week. Changing to YAML based configuration made it clear why this failed as the error message itself is also easily misinterpreted. Spend quite some time to understand what Fluentbit was really trying to tell me 😅

[Swaagie]

Also for people needing a quick workaround loading a filter using the -e command line parameter still works as expected.