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processor_fts: add Fluent Typed Scripting processor - #12589

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@edsiper edsiper commented Oct 16, 2026 •

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processor_fts: Fluent Typed Scripting

FTS is a new processor for writing telemetry policies in Lua with typed
access to logs, metrics and traces
. Policies read and edit records the way
the data actually is: 64-bit integers stay exact, binary stays binary,
timestamps keep nanoseconds, and OpenTelemetry resources, scopes and
attributes are first-class properties instead of raw metadata maps.

pipeline:
  inputs:
    - name: opentelemetry
      port: 4318
      processors:
        logs:
          - name: fts
            script: policy.lua
local fb = require("fluentbit")

function process(log)
    if log.body:get_string("path") == "/health" then
        return fb.DROP
    end

    fb.redact(log.body, {"authorization", "password", "access_token"})

    if fb.is_otel(log) then
        log.resource.attributes:set("deployment.environment.name", "production")
    end
end

Highlights

  • One model for three signals: process(log), process(metric) (per
    family) and process(span) share the same typed value API.
  • Transactional edits: each item commits or rolls back as a unit, including
    its resource and scope. error_mode decides between dropping and keeping the
    original on policy errors.
  • OpenTelemetry aware: per-record resource/scope edits, severity and trace
    context helpers, metric helpers (scale_metric, aggregate_metric,
    merge_histogram_buckets, copy_metric, extract_metric).
  • Bounded by design: per-callback instruction budget, policy memory limit,
    output size limit, restricted sandbox (no I/O, FFI, debug, loaders).
  • Fast: 18–45% less CPU than the equivalent lua processor on 5.1, see
    below.

The API reference is in plugins/processor_fts/README.md.

Performance

Release builds on the same machine, user+sys CPU and peak RSS (median). The
same policy runs as a lua processor on 5.1.0, as a lua processor on this
branch, and as an fts processor on this branch. Input is tail with 1M flat
records or 300k Kubernetes records, output is null.

Scenario lua 5.1 lua this branch fts fts vs lua 5.1 RSS lua 5.1 RSS fts
No-op policy 3.13 s 2.81 s 2.20 s −30% 22.4 MB 24.7 MB
Drop all 2.29 s 2.16 s 1.72 s −25% 17.5 MB 17.9 MB
Edit (remove + set) 3.53 s 3.23 s 2.33 s −34% 21.5 MB 23.4 MB
Read 5 fields + edit 3.55 s 3.27 s 2.90 s −18% 21.6 MB 23.1 MB
Kubernetes record edit 3.20 s 3.12 s 2.05 s −36% 25.5 MB 28.7 MB
Kubernetes nested field lift 3.20 s 3.12 s 2.20 s −31% 25.6 MB 28.9 MB
Policy + content_modifier 5.24 s 3.88 s 2.98 s −43% 21.5 MB 23.4 MB
content_modifier + policy 5.37 s 4.43 s 2.98 s −45% 21.4 MB 23.4 MB
Output processor edit 3.85 s 3.81 s 3.04 s −21% 75.7 MB 60.2 MB

flush is 0.2 s. With flush 0.02 (smaller chunks) the CPU results are the
same within 2%, and peak RSS is within 1.5 MB of the lua processor in every
input scenario. As an output processor, FTS uses 52 MB against 67 MB for
lua.

How:

  • FTS works on the same decoded chunk as every other native processor, so
    chains decode and encode each chunk once.
  • Policies edit chunk values in place under an undo log instead of copying
    records.
  • When FTS is the last processor, records are decoded into a per-chunk arena
    that borrows strings from the chunk buffer, and edits are allocated from the
    same arena.
  • Large buffers, such as complete chunks reaching output processors, are
    processed in windows (see below), so memory stays bounded.

Windowed log processing

Native processors decode the whole buffer before running, so an output
processor held every record of a stored chunk (several MB) decoded at once.
When all native processors of a run set the new
FLB_PROCESSOR_FLAG_LOG_WINDOWS flag, buffers larger than 64 KiB are
decoded, processed and encoded in windows of about 64 KiB or 1024 records.

  • Windows never split a group (for example one OpenTelemetry resource and
    scope), and an end marker always stays with its group.
  • Malformed buffers fall back to the single-chunk path.
  • fts and content_modifier set the flag. Other processors, filters used
    as processors and Lua processors keep the single-chunk path.
  • For FTS logs, a batch is one window, so output_limit and error_mode
    apply per window instead of per chunk. This is documented in the README.

Changes outside the plugin

FTS needed a few shared changes. Each one is a separate commit.

  • lib: cfl: arena objects use their natural alignment instead of the
    long double alignment, owned strings use finer size classes, and large
    arena strings are now aligned. Decoded record batches use about 25–30% less
    arena memory and about 20% less CPU. No public API change. This is the same
    patch as arena: pack objects, refine string size classes and align external allocations cfl#98.
  • processor:
    • logical record counts are carried through the chain to avoid recounting;
    • a failed chunk encode resets the encoder so records cannot leak into the
      next chunk;
    • windowed processing (above);
    • each run owns its chunk decoder and encoder. Before, the decoded chunk
      borrowed the first processor's decoder while later processors only held
      their own locks, and with output workers another thread could reset that
      decoder while records were still being read.
  • mp:
    • chunk record pooling, an optional per-chunk value arena and an
      allocation-free log record counter;
    • group-aligned log windows and appending chunk encoding;
    • group normalization can keep a leading end marker and an open trailing
      group. The existing functions keep their strict behaviour.
  • processor, output: a group whose start and end markers arrive in
    separate appends (for example split forward messages) keeps its markers
    through native processors, and through output processors when the stored
    chunk had them. The markers are kept only when the processor input already
    had them, so a processor that drops an end marker from a balanced input
    still loses the orphan start, as before.
  • output: processed profiles are exposed with their serialized size
    instead of the buffer capacity, as already done for traces.
  • log_event_decoder: reuse the unpack zone between records.
  • input_log: pass exact record counts to processors.
  • opentelemetry / out_opentelemetry: preserve typed OTLP fields (bytes,
    event name, dropped counts, flags) through Fluent Bit. OTLP JSON metrics keep
    the 5.1 behaviour of merging repeated series by labels (last value wins).
  • lib: cmetrics:
    • typed OTLP metric metadata (typed attributes, flags, exemplars, start
      times) is kept through the internal MessagePack format as an optional
      sidecar;
    • the same point metadata is also written to the external otlp tree that
      5.1 reads, so 5.1 nodes keep start times, flags and exemplars;
    • histogram buckets stay cumulative on the wire, unknown layout markers are
      ignored, and repeated label-less points keep the last value, as in 5.1;
    • typed attributes with no OTLP form (null, unsigned above INT64_MAX) fall
      back to the label attributes instead of dropping the metric.
  • lib: ctraces: OTLP decoders keep spans with an unknown span kind
    instead of rejecting them. MessagePack stores those kinds as unspecified,
    because 5.1 rejects the whole traces context otherwise.
  • processor_labels, processor_opentelemetry_envelope: list-handling and
    metadata ownership fixes found while testing FTS chains.

The bundled library changes are kept in their own commits so they can be sent
upstream.

Compatibility

  • New plugin, enabled with FLB_PROCESSOR_FTS (requires LuaJIT and yyjson).
  • The lua filter and processor are unchanged.
  • Internal MessagePack metrics stay readable by 5.1 and vice versa,
    including filesystem backlog written by 5.1, verified with 5.1.0 and 5.1.4
    release binaries in both directions. Traces were verified the same way with
    5.1.4. 5.1.0 already rejects traces written by master, because of the span
    flags field, which predates this PR.
  • OTLP output changes, all closer to the OTLP input:
    • log event_name, dropped attribute counts and flags are forwarded;
    • OTLP JSON output writes flags and eventName, and bytesValue as
      base64;
    • typed metric and span attributes are forwarded as received instead of
      being converted through labels;
    • invalid attributes are skipped with a warning instead of failing the
      whole payload.
  • An OTLP histogram forwarded from this version to a 5.1 node and exported
    by that node's opentelemetry output shows cumulative bucket counts,
    because 5.1 emits its stored buckets unchanged. 5.1's Prometheus outputs are
    correct.
  • Span kinds outside the OTLP range survive OTLP to OTLP, but become
    unspecified when stored in a chunk.
  • Group markers that span appends were previously removed by any native
    processor and now stay, as they do for pipelines without processors.
  • Struct additions in public headers are appended at the end.

Testing

Linux x86_64, debug build with -DFLB_TESTS_RUNTIME=On -DFLB_TESTS_INTERNAL=On.

  • Internal tests: 100/100 passed (ctest --test-dir build -j8).
  • Valgrind (--leak-check=full), clean: flb-it-fts, flb-it-processor,
    flb-it-mp, flb-it-mp_chunk_cobj, flb-it-log_event_decoder,
    flb-it-opentelemetry.
  • AddressSanitizer with clang 18 and gcc 9: flb-it-fts, flb-it-mp,
    flb-it-processor, flb-it-opentelemetry pass.
  • Every commit in the series builds, and the mp, processor and fts internal
    tests pass at each step, except one: flb-it-mp does not build at the
    scanner API commit until the following test commit. The two are separate
    because of the commit prefix rules.
  • cmetrics standalone unit tests: 23/23 passed. ctraces: 7/7 passed. Both are
    clean under Valgrind.

Integration suites:

pytest scenarios/processor_fts scenarios/in_opentelemetry \
       scenarios/out_opentelemetry scenarios/processor_labels scenarios/in_tail \
       scenarios/out_stdout scenarios/filter_lua scenarios/in_forward \
       scenarios/in_prometheus_remote_write scenarios/out_prometheus_exporter \
       scenarios/internal_metrics scenarios/filter_log_to_metrics \
       scenarios/security_protobuf scenarios/in_http scenarios/out_vivo_exporter \
       scenarios/in_storage_backlog -n 8
  • normal: 1126 passed, 137 skipped
  • VALGRIND=1 VALGRIND_STRICT=1: 1126 passed, 137 skipped. 623 Fluent Bit
    runs, no Valgrind errors and no definite leaks.

The complete tests/integration suite was also run. The only failures are
unrelated to this change:

  • out_kafka schema registry tests: this build has FLB_PROTOBUF_ENCODER
    off;
  • unix_socket_decode_status: this build has FLB_IN_UNIX_SOCKET off;
  • in_node_exporter_metrics systemd tests: they fail the same way with a
    master build on this machine.

Cross-version checks with 5.1.0 and 5.1.4 release binaries:

  • histogram buckets through forward 5.1→new, new→5.1 and new→new;
  • metrics start times and flags new→5.1.0→new and new→5.1.4→new;
  • traces new→5.1.4→new;
  • the 5.1.0 MessagePack fixtures.

Summary by CodeRabbit

  • New Features

    • Added the Fluent Typed Scripting processor for logs, metrics, and traces, with Lua policies, signal-specific helpers, and configurable execution, memory, and output limits.
    • Preserved OTLP metadata across metric conversions and improved support for typed attributes, histogram buckets, log event names, and dropped-attribute counts.
  • Bug Fixes

    • Improved log batch record counting and processing while preserving group boundaries.
    • Improved handling of unknown span kinds and OTLP byte values across supported formats.
  • Documentation

    • Added configuration guidance and examples for the Fluent Typed Scripting processor.

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coderabbitai Bot commented Oct 16, 2026 •

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Review in Change Stack →

📝 Walkthrough

This pull request adds the Fluent Typed Scripting processor for logs, metrics, and traces. It also updates OTLP metadata and histogram handling, improves log and trace conversion, and changes MessagePack, processor record-count, and arena-allocation paths.

Changes: Fluent Typed Scripting processor

Layer / File(s) Summary
Processor setup and runtime
cmake/plugins_options.cmake, plugins/CMakeLists.txt, plugins/processor_fts/*
Adds FTS build options and plugin registration, runtime configuration, Lua helpers, and documentation. The runtime applies restrictions and configured memory and instruction limits.
Typed values and log processing
plugins/processor_fts/fts_values.c, plugins/processor_fts/fts_logs.c, plugins/processor_fts/fts_log_helpers.lua, plugins/processor_fts/fts_value_helpers.lua
Adds typed Lua values, mutation rollback, log policy validation, and staged log output with record-level commit, rollback, and drop handling.
Telemetry processing
plugins/processor_fts/fts_proto.*, plugins/processor_fts/fts_telemetry.*, plugins/processor_fts/fts_metrics.c, plugins/processor_fts/fts_traces.c, plugins/processor_fts/fts_telemetry_helpers.lua
Adds protobuf conversion and policy callbacks for metrics and traces. The adapters validate and stage edits and emissions, then handle failures according to error_mode.
FTS regression coverage
tests/internal/fts.c, tests/internal/CMakeLists.txt, tests/integration/scenarios/processor_fts/tests/*
Adds internal and integration tests for policy execution, typed values, limits, rollback, signal handling, processor chains, and OTLP interoperability.

OTLP metric metadata and histogram handling

Layer / File(s) Summary
Metric metadata storage and serialization
lib/cmetrics/include/cmetrics/*, lib/cmetrics/src/cmt_otlp_metadata.c, lib/cmetrics/src/cmt_decode_msgpack.c, lib/cmetrics/src/cmt_encode_msgpack.c, lib/cmetrics/src/cmt_map.c
Adds map- and sample-owned OTLP metadata and MessagePack sidecar packing and restoration. Cleanup and counter allow_reset decoding are updated.
OTLP metric conversion and concatenation
lib/cmetrics/src/cmt_decode_opentelemetry.c, lib/cmetrics/src/cmt_encode_opentelemetry.c, src/opentelemetry/flb_opentelemetry_metrics.c, lib/cmetrics/src/cmt_cat.c, plugins/processor_labels/labels.c
Stores metric metadata on maps and samples, handles repeated unlabeled points, preserves metadata during concatenation, and converts histogram counts between cumulative and per-bucket forms.
Metric regression coverage
lib/cmetrics/tests/*, tests/internal/opentelemetry.c, tests/integration/scenarios/processor_fts/tests/test_fts_native_interop.py
Adds tests for metadata round trips, malformed sidecars, histogram compatibility, repeated series, typed attributes, and concatenation.

OpenTelemetry logs and traces interoperability

Layer / File(s) Summary
Log metadata conversion
src/opentelemetry/flb_opentelemetry_logs.c, src/opentelemetry/flb_opentelemetry_otlp_json.c, plugins/out_opentelemetry/opentelemetry_logs.c
Adds conversion for log flags, event names, and dropped-attribute counts from OTLP metadata and group context.
AnyValue and span-kind conversion
src/opentelemetry/flb_opentelemetry_utils.c, src/opentelemetry/flb_opentelemetry_traces.c, lib/ctraces/src/*
Adds base64 bytesValue handling and signed integer conversion. Trace decoders and encoders preserve signed and unknown span-kind values.
Interoperability tests
tests/internal/opentelemetry.c, lib/ctraces/tests/*, tests/integration/scenarios/processor_fts/tests/test_fts_native_interop.py
Adds coverage for byte values, integer boundaries, invalid attributes, and signed or unknown span kinds.

MessagePack, processor, and arena infrastructure

Layer / File(s) Summary
MessagePack scanning and chunk storage
include/fluent-bit/flb_mp*.h, src/flb_mp.c, src/flb_log_event_decoder.c, tests/internal/mp.c, tests/internal/mp_chunk_cobj.c
Adds log-record scanning, group-aware windows, arena-backed value conversion, pooled chunk records, and scratch-buffer encoding. Decoder zone handling and associated tests are updated.
Processor record counts and buffer handling
include/fluent-bit/flb_processor.h, src/flb_processor.c, src/flb_input_log.c, src/flb_json.c, include/fluent-bit/flb_output.h, plugins/processor_opentelemetry_envelope/otel_envelope.c, tests/internal/processor.c
Adds processor input and output record counts, reuses valid counts in log processing, uses iterative mutable JSON conversion, and updates output sizing and failure cleanup.
Arena allocation and benchmark
lib/cfl/src/cfl_arena.c, lib/cfl/src/cfl_arena_internal.h, lib/cfl/src/cfl_array.c, lib/cfl/src/cfl_kvlist.c, lib/cfl/src/cfl_sds.c, lib/cfl/tests/arena.c, lib/cfl/benchmarks/*, lib/cfl/ARENA.md, lib/cfl/CHANGELOG.md
Adds object-aligned arena allocation, a bump-allocation path, and revised SDS size classes. Adds arena tests, documentation, and a decoded-record benchmark.

Priority: ➖ Normal

Estimated code review effort: 5 (Critical) | ~180 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Input as Fluent Bit input
  participant FTS as processor_fts
  participant Runtime as fts_runtime
  participant Policy as Lua policy
  participant Output as Fluent Bit output
  Input->>FTS: pass log, metric, or trace data
  FTS->>Runtime: invoke signal callback
  Runtime->>Policy: execute callback within configured limits
  Policy-->>Runtime: return edits or policy result
  Runtime-->>FTS: return callback result
  FTS->>Output: pass staged output
Loading
Merge Risk: 🔵 Low · up to e0d9a

The change is broadly mergeable, with two narrow follow-ups. Large log batches that contain unusual stray group-end markers can be forwarded with extra end markers. The FTS protobuf error path may also free memory with a different allocator than the one that allocated it when embedded jemalloc is used.

Pre-merge checks: Passed 4 · Failed 1

Failed Failed checks: 1 warning

Check name Status Explanation Resolution
Docstring Coverage Warning Docstring coverage is 23.18% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 535 functions across 67 files. (5 skipped… Write docstrings for the functions missing them to satisfy the coverage threshold.
Passed Passed checks: 4 passed
Check name Status Explanation
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 clearly and concisely identifies the main change: adding the Fluent Typed Scripting processor.
Full details: Docstring Coverage

Explanation

Docstring coverage is 23.18% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 535 functions across 67 files. (5 skipped: 5 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

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Carry typed OTLP data point and family metadata (typed attributes,
flags, exemplars, start times) as an optional sidecar of the internal
msgpack format. Histogram buckets stay cumulative on the wire so 5.1
readers and writers keep interoperating, unknown layout markers are
ignored, and samples with metadata merge by labels in cmt_cat.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Keep proto3 enum values received on the wire instead of rejecting the
span, matching protobuf decoding semantics.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Pool chunk record wrappers, add an opt-in value arena for chunks that
are only serialized, and add an allocation-free scanner that counts
log records and detects plain logs. A failed chunk encode now resets
the encoder so partial records never leak into the next chunk.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Output workers run on small coroutine stacks; avoid recursion when
rendering nested values.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Carry known logical record counts through the processor chain so
they are not recounted after every unit. On a failed chunk encode,
reset the encoder and release the chunk so records cannot leak into
the next chunk.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Keep typed attributes and metadata for metrics, traces and logs. OTLP
JSON metrics merge repeated series by labels as before, bytesValue is
decoded as binary, and invalid attribute warnings are reported once
per list.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
FTS runs Lua policies with typed access to logs, metrics and traces:
exact integers, binary values, nanosecond timestamps and first-class
OpenTelemetry resources, scopes and attributes. Edits are
transactional per item and bounded by instruction, memory and output
limits.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
A group still open at the end of a batch was closed, and an end marker
before any start was dropped, so records of a group split across appends
moved out of it. Keep the open group open, reopening the source context
when the last output group differs, and forward the leading end marker.
Records before it keep no context and cannot set one.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Context changes were detected by matching keys by name, so with duplicate
keys an edit that set a key to its first value, or changed a later copy,
looked unchanged and was discarded. Maps with duplicate keys are now
compared by position; other maps keep the order independent comparison.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
fb.parse_json() checked duplicate keys with an unseeded hash table, which
crafted colliding keys can make quadratic, without a bound when JIT
disables the instruction budget. Sorting the keys is O(n log n) for any
input and is charged to the instruction budget.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
…JSON

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Typed data point attributes with no OTLP form, such as null values or
unsigned integers above INT64_MAX, made the conversion return NULL, which
was reported as an allocation error and dropped the whole metric. Check
the values first and keep the label derived attributes for them, so a
NULL conversion result is again only an allocation failure.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Messages built for typed telemetry are released by protobuf-c with the
system allocator, but attribute keys were copied with flb_strdup(), which
uses the embedded jemalloc when it is enabled.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Processed profiles were exposed with the buffer capacity, which can exceed
the serialized bytes and append zeroed memory to the event chunk, as
already fixed for traces.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Corrupting the count of a 16 or 32 bit array or map header made the
msgpack-c fallback request gigabytes, which fails under AddressSanitizer.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Derive the appended literal length instead of hardcoding it, which read
past the literal, and use the Windows descriptor functions to capture
stderr.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
…uilds

LuaJIT raises errors by resetting the C stack pointer instead of calling
longjmp(), so AddressSanitizer keeps the redzones of the skipped frames
poisoned and later calls report bogus stack errors, as seen with the gcc 9
and clang 12 sanitizer jobs. After a failed protected call, unpoison the
dead stack below the current frame. Builds without the sanitizer are not
affected.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Output processors normalize their result. Keep the group markers that
span chunks only when the stored chunk itself had them, like outputs
without processors receive them.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Native uint64 families that a policy cannot process are copied back with
cmt_cat in keep mode, which merges them into a policy output family of the
same name and gives the merged family their routing. Treat that collision
as a batch failure, so keep forwards the original families.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
- Write the OTLP point and family metadata to the external otlp tree as
  well, keyed by series hash and timestamp, so Fluent Bit 5.1 readers keep
  start times, flags and exemplars. Readers of the sidecar drop that copy.
- Copy metadata with a recursive copy instead of a msgpack round trip,
  which failed for values nested deeper than the msgpack limit.
- Skip only the sidecar entries that cannot be read back.
- Append allow_reset to the decode context to keep its field layout.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Releases up to 5.1 reject a whole traces context when a span kind is out
of the known range. The OTLP decoders still keep the spans with unknown
kinds, and msgpack stores those kinds as unspecified.

Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>
Signed-off-by: Eduardo Silva <eduardo@chronosphere.io>

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Actionable comments posted: 1


  • 🪄 Fix comments: Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @src/flb_processor.c:
- Around line 1588-1603: Update run_log_windows to pass
FLB_MP_GROUPS_KEEP_LEADING_END to at most the first eligible window, tracking
whether a window received the flag with a local state variable. Preserve the
existing seen_start behavior and trailing-open flag handling.

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Reviewing files that changed from the base of the PR and between 156959c and e0d9a0e.

📒 Files selected for processing: 43
  • include/fluent-bit/flb_mp.h
  • include/fluent-bit/flb_mp_chunk.h
  • include/fluent-bit/flb_output.h
  • include/fluent-bit/flb_processor.h
  • lib/cfl/ARENA.md
  • lib/cfl/CHANGELOG.md
  • lib/cfl/benchmarks/CMakeLists.txt
  • lib/cfl/benchmarks/README.md
  • lib/cfl/benchmarks/records.c
  • lib/cfl/src/cfl_arena.c
  • lib/cfl/src/cfl_arena_internal.h
  • lib/cfl/src/cfl_array.c
  • lib/cfl/src/cfl_kvlist.c
  • lib/cfl/src/cfl_sds.c
  • lib/cfl/tests/arena.c
  • lib/cmetrics/include/cmetrics/cmt_decode_msgpack.h
  • lib/cmetrics/include/cmetrics/cmt_otlp_metadata.h
  • lib/cmetrics/src/cmt_encode_msgpack.c
  • lib/cmetrics/src/cmt_encode_opentelemetry.c
  • lib/cmetrics/src/cmt_otlp_metadata.c
  • lib/cmetrics/tests/opentelemetry.c
  • lib/ctraces/src/ctr_encode_msgpack.c
  • lib/ctraces/tests/decoding.c
  • plugins/processor_content_modifier/cm.c
  • plugins/processor_fts/README.md
  • plugins/processor_fts/fts.c
  • plugins/processor_fts/fts.h
  • plugins/processor_fts/fts_logs.c
  • plugins/processor_fts/fts_metrics.c
  • plugins/processor_fts/fts_proto.c
  • plugins/processor_fts/fts_runtime.c
  • plugins/processor_fts/fts_values.c
  • src/flb_mp.c
  • src/flb_processor.c
  • src/opentelemetry/flb_opentelemetry_metrics.c
  • tests/integration/scenarios/processor_fts/tests/test_fts_native_interop.py
  • tests/integration/scenarios/processor_fts/tests/test_fts_pipeline.py
  • tests/integration/scenarios/processor_fts/tests/test_fts_records.py
  • tests/integration/scenarios/processor_fts/tests/test_fts_security_batches.py
  • tests/internal/fts.c
  • tests/internal/mp.c
  • tests/internal/opentelemetry.c
  • tests/internal/processor.c
🚧 Files skipped from review as they are similar to previous changes: 2
  • lib/cmetrics/src/cmt_encode_opentelemetry.c
  • tests/internal/opentelemetry.c

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Comment thread src/flb_processor.c
Comment on lines +1588 to +1603
window_flags = 0;
if (chunk_has_group_markers(chunk_cobj)) {
input_flags = input_group_flags(group_flags, input, input_size);
if (!seen_start) {
window_flags |= input_flags & FLB_MP_GROUPS_KEEP_LEADING_END;
}
if (w == window_count - 1) {
window_flags |= input_flags & FLB_MP_GROUPS_KEEP_TRAILING_OPEN;
}
}
/* only inputs opening with a continued group need the start count */
if (*group_flags > 0 && (*group_flags & FLB_MP_GROUPS_KEEP_LEADING_END) &&
!seen_start &&
flb_mp_log_group_starts((char *) data + offset, windows[w].end - offset) > 0) {
seen_start = FLB_TRUE;
}

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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

Windowed runs can keep more than one leading end marker.

In the single-chunk path, FLB_MP_GROUPS_KEEP_LEADING_END keeps only the first end marker that comes before any start in the whole buffer. In run_log_windows, every window gets this flag until seen_start becomes true. Each window is normalized independently, so each window keeps its own first stray end.

Example input: r0 E <1024+ records> E r1, with no group start. The single-chunk path outputs one E. The windowed path outputs two E markers, so its bytes differ from the single-chunk output. The test processor_log_windows_match_single_chunk asserts that both paths produce the same bytes, but its fixture does not contain this case. Downstream, the second E is forwarded as a group end for the next append.

Fix: stop passing the leading-end flag after the first window that received it.

Proposed fix
--- "a/src/flb_processor.c"
+++ "b/src/flb_processor.c"
@@ -1585,16 +1585,20 @@
          * Boundary markers of the input stay with the window holding them: a
          * leading end until a group starts, the open group in the last window.
          */
         window_flags = 0;
         if (chunk_has_group_markers(chunk_cobj)) {
             input_flags = input_group_flags(group_flags, input, input_size);
-            if (!seen_start) {
+            if (!seen_start && !leading_end_done) {
                 window_flags |= input_flags & FLB_MP_GROUPS_KEEP_LEADING_END;
             }
             if (w == window_count - 1) {
                 window_flags |= input_flags & FLB_MP_GROUPS_KEEP_TRAILING_OPEN;
             }
         }
+        /* only one window may keep the leading end marker */
+        if (window_flags & FLB_MP_GROUPS_KEEP_LEADING_END) {
+            leading_end_done = FLB_TRUE;
+        }
         /* only inputs opening with a continued group need the start count */
         if (*group_flags > 0 && (*group_flags & FLB_MP_GROUPS_KEEP_LEADING_END) &&
             !seen_start &&

Declare int leading_end_done = FLB_FALSE; with the other locals of run_log_windows.

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Review comment at @src/flb_processor.c around lines 1588 - 1603:
Update run_log_windows to pass FLB_MP_GROUPS_KEEP_LEADING_END to at most the
first eligible window, tracking whether a window received the flag with a local
state variable. Preserve the existing seen_start behavior and trailing-open flag
handling.

After applying the fix, consider running `coderabbit review --agent` for local
review. Visit https://docs.coderabbit.ai/cli?utm_source=ghpr

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