plugin_proxy: add config map to the plugin registration

[iypetrov]

Extend the proxy plugin registration flow so input and output Go plugins can attach a flb_config_map schema, enabling the same property validation native plugins already receive. Custom plugins are excluded because they don't go through the property-check callback path. For more context can check this discussion.

Issue #11776

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Testing
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Documentation

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Backporting

• Backport to latest stable release.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

Summary by CodeRabbit

• Bug Fixes
  • Plugin registration now carries plugin configuration settings through correctly for both input and output plugins.
  • This improves consistency when loading plugins that rely on custom configuration options.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a config_map field to struct flb_plugin_proxy_def in the plugin proxy header, and propagates that field into created output and input plugin instances during proxy registration in flb_plugin_proxy.c. A comment describing the registration process is also updated.

Changes

Proxy Config Map Propagation

Layer / File(s)	Summary
Config map struct field include/fluent-bit/flb_plugin_proxy.h	Adds a config_map pointer member to struct flb_plugin_proxy_def.
Registration wiring src/flb_plugin_proxy.c	Sets out->config_map and in->config_map from the proxy definition during output/input plugin registration, and updates a related comment.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Poem

A rabbit hops through proxy code,
Carrying a map along the road,
Config now travels, field to field,
No longer hidden, no longer sealed,
Output and input, both in tow. 🐇

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding config map support to plugin registration.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: a2aacd87b2

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[chatgpt-codex-connector]

Propagate proxy config maps to custom plugins

When a Go proxy registers as FLB_PROXY_CUSTOM_PLUGIN and sets this new field, it is dropped because flb_proxy_register_custom() only copies flags/name/description into struct flb_custom_plugin. The custom path does have config-map validation (flb_custom_plugin_property_check() gates on p->config_map), so those plugins will silently accept unknown properties and won't get defaults/dynamic-env handling even though input/output proxy plugins do.

Useful? React with 👍 / 👎.

[iypetrov]

@cosmo0920 @edsiper

[iypetrov]

@cosmo0920 when you have time, can you rerun the failing tests?

[iypetrov]

@edsiper this PR implements the suggestion from #11788 (comment) - when this one got merged, I will close the PR with previous implementation in fluent-bit repo and will start working on the required change in fluent-bit-go.