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plugin_proxy: enable event_type specification for proxy plugins#11011

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jmccormick7 wants to merge 5 commits intofluent:masterfrom
jmccormick7:enable-metric-proxy-plugins
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plugin_proxy: enable event_type specification for proxy plugins#11011
jmccormick7 wants to merge 5 commits intofluent:masterfrom
jmccormick7:enable-metric-proxy-plugins

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@jmccormick7 jmccormick7 commented Oct 10, 2025

This commit adds event_type to the flb_plugin_proxy_def struct. This allows for the setting of event_type to a value other than the default log only initialization.

In the flb_plugin_proxy_register function default behavior is enforced by checking for unset event_type values. When unset (a value of 0) then log behavior is defaulted. No need for incorrect value checking since this was not a set field in the past. Unset fields are set as current behavior dictates and future use cases using incorrect values can be treated as user error.

Input use case does not use event-type and is unaffected by this change.

Addresses #10995

This corresponding PR in the fluent-bit-go library enables the ability to allow Go plugins to register their event types PR 80


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Testing
Before we can approve your change; please submit the following in a comment:

  • [N/A] Example configuration file for the change
  • [N/A] Debug log output from testing the change
  • Attached Valgrind output that shows no leaks or memory corruption was found
100% tests passed, 0 tests failed out of 164

Label Time Summary:
internal    =  85.38 sec*proc (70 tests)
runtime     = 2026.55 sec*proc (83 tests)

Total Test time (real) = 2212.60 sec
==46444== 
==46444== HEAP SUMMARY:
==46444==     in use at exit: 0 bytes in 0 blocks
==46444==   total heap usage: 5,012 allocs, 5,012 frees, 54,842,164 bytes allocated
==46444== 
==46444== All heap blocks were freed -- no leaks are possible
==46444== 
==46444== For lists of detected and suppressed errors, rerun with: -s
==46444== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

If this is a change to packaging of containers or native binaries then please confirm it works for all targets.

  • Run local packaging test showing all targets (including any new ones) build.
  • Set ok-package-test label to test for all targets (requires maintainer to do).

Documentation

  • Documentation required for this feature

Backporting

  • Backport to latest stable release.

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

  • New Features

    • Added event type support to proxy plugin definitions (logs/metrics/traces) with a default fallback to logs when unspecified.
  • Tests

    • Added a Go-based proxy output plugin, Go module, and build script for test plugins.
    • Introduced a proxy logs runtime test, config snippet, and a shell expectation script.
    • Enabled Linux-specific inclusion and adjusted test environment to include build path.
  • Chores

    • Updated proxy registration behavior and test build configuration.

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coderabbitai bot commented Oct 10, 2025

📝 Walkthrough

Walkthrough

Added an event_type field to the plugin proxy definition and propagated it during registration; switched proxy allocation to zeroed memory; and added runtime tests including a Go-based logs output plugin, a build script, a test config, and a shell expectation script.

Changes

Cohort / File(s) Summary
Plugin Proxy API
include/fluent-bit/flb_plugin_proxy.h
Added public field int event_type to struct flb_plugin_proxy_def.
Plugin Proxy Implementation
src/flb_plugin_proxy.c
Propagate def->event_type into registered outputs (defaults to FLB_OUTPUT_LOGS when zero); add input plugin to in_plugins list during registration; allocate proxy definition with flb_calloc instead of flb_malloc.
Test Harness Config
tests/runtime_shell/CMakeLists.txt, tests/runtime_shell/conf/proxy_logs_test.conf
Conditionally include proxy_logs_expect.sh for Linux; set FLB_BUILD and append to FLB_BIN; added runtime config for a dummy input and test_logs_go + file outputs.
Go Plugin & Build Artifacts
tests/runtime_shell/go_plugins/logs_output.go, tests/runtime_shell/go_plugins/go.mod, tests/runtime_shell/go_plugins/build_test_plugins.sh
New Go output plugin (test_logs_go) with exported plugin lifecycle/flush functions; go.mod for module/deps; build script installs Go if needed, verifies CGO, and builds the plugin shared object.
Runtime Expectation Script
tests/runtime_shell/proxy_logs_expect.sh
New shell test script that runs Fluent Bit with the test plugin, captures stdout to validate plugin output, and reports success/failure.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

"I hopped in code with joy and hops,
Added a bit for logs and props,
Built a plugin, tested run,
Captured output — carrots won,
Little rabbit dances, bops! 🥕🐇"

🚥 Pre-merge checks | ✅ 2 | ❌ 1
❌ Failed checks (1 warning)
Check name Status Explanation Resolution
Docstring Coverage ⚠️ Warning Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Write docstrings for the functions missing them to satisfy the coverage threshold.
✅ Passed checks (2 passed)
Check name Status Explanation
Description Check ✅ Passed Check skipped - CodeRabbit’s high-level summary is enabled.
Title check ✅ Passed The title directly and clearly describes the main change: enabling proxy plugins to specify event_type, which is the primary objective of this PR.

✏️ Tip: You can configure your own custom pre-merge checks in the settings.

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Actionable comments posted: 2

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 0def4e6 and 8b70738.

📒 Files selected for processing (2)
  • include/fluent-bit/flb_plugin_proxy.h (1 hunks)
  • src/flb_plugin_proxy.c (2 hunks)

@cosmo0920
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If we proceed to address this issue, we need to send another PR into here https://github.com/chronosphereio/calyptia-plugin to handle event_type as well.

@jmccormick7
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jmccormick7 commented Oct 17, 2025

If we proceed to address this issue, we need to send another PR into here https://github.com/chronosphereio/calyptia-plugin to handle event_type as well.

@cosmo0920 I can open a PR in that repository tonight!

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Looks good to me. But this PR has a possible ABI breakage of the Golang plugin interface. So, we need to test it before merging.

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@cosmo0920 How would you prefer I do testing beyond the unit tests? I've done some manual testing that I can document, but is there any formalized regression testing or tests for proxy plugins?

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cosmo0920 commented Nov 7, 2025

How about adding runtime shell test cases with precompiled Golang shared objects here?

https://github.com/fluent/fluent-bit/tree/master/tests/runtime_shell
Or, leaving as-is is still good but it tends to be delayed for reviewing without unit test addtions.

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jmccormick7 commented Nov 12, 2025

@cosmo0920 I have added a runtime test that build and test a go plugin shared object. Please let me know if there are any improvements or other additions I can provide to speed up the timeline!

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Actionable comments posted: 4

🧹 Nitpick comments (5)
tests/runtime_shell/go_plugins/build_test_plugins.sh (1)

98-98: Consider using FLB_BUILD variable instead of hardcoded path.

The CMakeLists.txt now exports FLB_BUILD to the environment. Consider using $FLB_BUILD instead of constructing $BUILD_DIR to ensure consistency with the test environment.

Apply this diff:

-    CGO_ENABLED=1 GO111MODULE=on go build -buildmode=c-shared -v -ldflags="-s -w" -o $BUILD_DIR/test_logs_go.so logs_output.go
+    CGO_ENABLED=1 GO111MODULE=on go build -buildmode=c-shared -v -ldflags="-s -w" -o ${FLB_BUILD:-$BUILD_DIR}/test_logs_go.so logs_output.go
tests/runtime_shell/proxy_logs_expect.sh (2)

19-19: Use FLB_BUILD variable for consistent path construction.

The script hardcodes $FLB_ROOT/build/test_logs_go.so, but the CMakeLists.txt now provides FLB_BUILD in the environment for this purpose.

Apply this diff:

-    $FLB_BIN -e $FLB_ROOT/build/test_logs_go.so -c $FLB_RUNTIME_SHELL_CONF/proxy_logs_test.conf > "$STDOUT_OUTPUT_FILE" 2>&1 &
+    $FLB_BIN -e $FLB_BUILD/test_logs_go.so -c $FLB_RUNTIME_SHELL_CONF/proxy_logs_test.conf > "$STDOUT_OUTPUT_FILE" 2>&1 &

22-22: Replace hardcoded sleep with signal file polling.

The hardcoded sleep 3 is fragile and can cause flakiness in tests. Consider polling for the SIGNAL_FILE_PATH or checking the process output instead of using a fixed delay.

tests/runtime_shell/go_plugins/test_logs_go.h (1)

1-92: Consider excluding auto-generated CGO headers from version control.

This file is marked as auto-generated by cmd/cgo and should not be manually edited. Consider adding *.h or specifically test_logs_go.h to .gitignore in this directory, and generate it during the build process instead.

tests/runtime_shell/go_plugins/logs_output.go (1)

28-28: Consider using the timestamp from GetRecord.

The timestamp returned by GetRecord (second return value) is currently ignored. While this is acceptable for a test plugin, consider whether timestamp information would be useful for test verification.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 82d792a and 74c83d1.

⛔ Files ignored due to path filters (1)
  • tests/runtime_shell/go_plugins/go.sum is excluded by !**/*.sum
📒 Files selected for processing (7)
  • tests/runtime_shell/CMakeLists.txt (2 hunks)
  • tests/runtime_shell/conf/proxy_logs_test.conf (1 hunks)
  • tests/runtime_shell/go_plugins/build_test_plugins.sh (1 hunks)
  • tests/runtime_shell/go_plugins/go.mod (1 hunks)
  • tests/runtime_shell/go_plugins/logs_output.go (1 hunks)
  • tests/runtime_shell/go_plugins/test_logs_go.h (1 hunks)
  • tests/runtime_shell/proxy_logs_expect.sh (1 hunks)
🧰 Additional context used
🧠 Learnings (3)
📚 Learning: 2025-08-31T12:46:11.940Z
Learnt from: ThomasDevoogdt
Repo: fluent/fluent-bit PR: 9277
File: .github/workflows/pr-compile-check.yaml:147-151
Timestamp: 2025-08-31T12:46:11.940Z
Learning: In fluent-bit CMakeLists.txt, the system library preference flags are defined as FLB_PREFER_SYSTEM_LIB_ZSTD and FLB_PREFER_SYSTEM_LIB_KAFKA with the FLB_ prefix.

Applied to files:

  • tests/runtime_shell/CMakeLists.txt
📚 Learning: 2025-08-31T12:46:11.940Z
Learnt from: ThomasDevoogdt
Repo: fluent/fluent-bit PR: 9277
File: .github/workflows/pr-compile-check.yaml:147-151
Timestamp: 2025-08-31T12:46:11.940Z
Learning: In fluent-bit, the correct CMake flag for using system librdkafka is `FLB_PREFER_SYSTEM_LIB_KAFKA=ON`.

Applied to files:

  • tests/runtime_shell/CMakeLists.txt
📚 Learning: 2025-09-04T07:28:37.083Z
Learnt from: cosmo0920
Repo: fluent/fluent-bit PR: 10832
File: src/wasm/CMakeLists.txt:112-131
Timestamp: 2025-09-04T07:28:37.083Z
Learning: In fluent-bit CMake files, the user cosmo0920 prefers treating Git as a command rather than a package, emphasizing that Git is not a pkg-config retrievable package but just a command.

Applied to files:

  • tests/runtime_shell/CMakeLists.txt
🧬 Code graph analysis (1)
tests/runtime_shell/go_plugins/test_logs_go.h (1)
tests/runtime_shell/go_plugins/logs_output.go (4)
  • FLBPluginRegister (12-15)
  • FLBPluginInit (18-20)
  • FLBPluginFlushCtx (23-39)
  • FLBPluginExit (42-44)
🔇 Additional comments (7)
tests/runtime_shell/CMakeLists.txt (2)

18-18: LGTM!

The addition of the proxy logs test to the test suite is appropriate.


31-32: LGTM!

Adding the FLB_BUILD environment variable enables tests to reference the build directory, which is useful for locating built artifacts like the test plugin shared object.

tests/runtime_shell/conf/proxy_logs_test.conf (1)

1-21: LGTM!

The test configuration is well-structured for validating the proxy logs functionality. The use of environment variables for the signal file path enables flexible test execution.

tests/runtime_shell/go_plugins/logs_output.go (2)

11-15: LGTM!

The registration function correctly delegates to the fluent-bit-go output package with appropriate plugin name and description.


22-39: LGTM!

The flush implementation correctly decodes records and outputs them to stdout for test verification. The error handling is appropriate for a test plugin.

tests/runtime_shell/go_plugins/go.mod (2)

3-3: The Go version 1.25.1 is valid and exists.

The latest stable Go release is Go 1.25.3 (released October 13, 2025), and Go 1.25.1 was released prior to that. The code's specification of go 1.25.1 is legitimate, though not the latest version available. No changes are required.

Likely an incorrect or invalid review comment.


6-6: Review comment is incorrect — PR 80 is open, not merged.

PR 80 ("Enable metric output plugins") in fluent-bit-go is currently open as of October 10, 2025 and has not been merged. Additionally, the plugin code (logs_output.go) does not use or require event_type support. The current dependency version is appropriate for the code's functionality.

Likely an incorrect or invalid review comment.

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Looks good. With the newly added unit test case for confirming backward compatibility, this PR ensures backward compatibility.

This commit adds event_type to the flb_plugin_proxy_def struct. This allows for the setting
of event_type to a value other than the default log only initialization.

In the flb_plugin_proxy_register function default behaviour is enforced by checking for unset event_type vlaues.
When unset (a value of 0) then log behaviour is defaulted. No need for incorrect value checking since this
was not a set field in the past. Unset fields are set as current behavior dicates and future usecases using incorrect values can be treated as user error.

Input use case does not use event-type and is unaffected by this change.

Signed-off-by: jmccormick7 <jcm258@case.edu>
… malloc

Changing intialization to use calloc instead of malloc so that emtpy fields are 0 initialized.
Specifically for the event_type addition.

Signed-off-by: jmccormick7 <jcm258@case.edu>
This commit adds a runtime shell test for the go plugin interface.
A dummy go output plugin is added to the directories, and a test that builds
the plugin shared object and then tests that it works and writes the output.
This test ensures that the go proxy interface is working as expected.

This was tested in the devcontainer using ctest.

Signed-off-by: jmccormick7 <jcm258@case.edu>
Signed-off-by: jmccormick7 <jcm258@case.edu>
This commit makes the go proxy a test that only runs on Linux
using the CMAKE_SYSTEM_NAME. It also removes an autogenerated
header file from the go compile that should not have been commited.

Signed-off-by: jmccormick7 <jcm258@case.edu>
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