out_s3: add format=parquet with selectable page compression codecs

[rituparnakhaund]

The S3 output plugin currently overloads the compression option to handle both byte-level compression (gzip, zstd, snappy) and format conversion (parquet). This makes it impossible
for users to produce Parquet files with page-level compression, because compression can only hold one value.

When compression=parquet is set, the code path ultimately calls gparquet_arrow_file_writer_new_arrow with NULL for writer properties. This causes the Arrow GLib binding to use parquet::default_writer_properties(), which sets the page-level codec to Compression::UNCOMPRESSED.
Every column page ends up uncompressed despite the key being "compression" ?

This patch separates concerns:

• format now accepts parquet (in addition to existing json_lines and otlp_json), controlling the output serialization format.
• compression controls the byte-level codec. When format=parquet, the compression value (snappy, zstd, gzip) is applied as the Parquet page-level codec instead of wrapping the file
  externally.
• Default page-level codec for Parquet is snappy, matching the industry standard (Spark, PyArrow, Hive all default to snappy).

Backwards compatibility is preserved: compression=parquet still works but emits a deprecation warning and maps to format=parquet with no page-level compression (identical to current
behavior).

Addresses feedback from #10691 requesting codec and page size configurability.

---

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

• Example configuration file for the change

Example configuration:
  [SERVICE]
      Flush     1
      Log_Level info
      
  [INPUT]
      Name    dummy
      Tag     test
      Rate    5
      Dummy   {"impressionId":"AAAAAA","level":"INFO","seedAsin":"B0SEED1","ts":1748522000000}
      
  [OUTPUT]
      Name              s3
      Match             test
      bucket            my-bucket
      region            us-east-1
      format            parquet
      compression       snappy
      use_put_object    On
      upload_timeout    60s
      total_file_size   50M
      s3_key_format     /parquet-test/dt=%Y-%m-%d/h=%H/$UUID.parquet

Verified with parquet-tools inspect:

Before (current master):
compression: UNCOMPRESSED (space_saved: 0%)

After this patch:
compression: SNAPPY

[X] Debug log output from testing the change :

Testing strategy : Ran build/bin/fluent-bit locally on my mac to write to my s3 bucket with different configs.
Here are the e2e-tests.txt

• Attached Valgrind output that shows no leaks or memory corruption was found
  Individually ran this for each of the tests and no corruption found. The 17 tests are taking too long, so will post here as soon as I see an update.

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

• [n/a] 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

fluent/fluent-bit-docs#2591

Backporting

• [n/a] Backport to latest stable release. (unsure actually)

---

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

  • S3 output supports Parquet format with selectable page-level codecs (SNAPPY, GZIP, ZSTD, NONE). Parquet conversion occurs before upload and enforces compatible options.

• Bug Fixes

  • Parquet conversion failures: immediate uploads are retried; buffered uploads fall back to raw payload to avoid data loss.

• Chores

  • compression=parquet deprecated with a warning; config help updated.

• Tests

  • Added tests validating Parquet outputs for each codec.

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ℹ️ Recent review info

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Run ID: d75f62ff-1652-4037-8717-d4734f53a73f

📥 Commits

Reviewing files that changed from the base of the PR and between daf983a and d26fe19.

📒 Files selected for processing (7)

• include/fluent-bit/aws/flb_aws_compress.h
• plugins/out_s3/s3.c
• plugins/out_s3/s3.h
• src/aws/compression/arrow/compress.c
• src/aws/compression/arrow/compress.h
• src/aws/flb_aws_compress.c
• tests/internal/aws_compress.c

💤 Files with no reviewable changes (1)

• src/aws/flb_aws_compress.c

🚧 Files skipped from review as they are similar to previous changes (5)

• src/aws/compression/arrow/compress.h
• include/fluent-bit/aws/flb_aws_compress.h
• src/aws/compression/arrow/compress.c
• tests/internal/aws_compress.c
• plugins/out_s3/s3.c

---

📝 Walkthrough

Walkthrough

Adds runtime-selectable Parquet page-level compression codecs, updates the Parquet conversion API to accept a codec, maps/configures codecs in the S3 plugin and upload flow, adjusts payload cleanup, and adds unit tests for Parquet outputs.

Changes

S3 Parquet Page-Level Compression

Layer / File(s)	Summary
Parquet codec constants & API contract include/fluent-bit/aws/flb_aws_compress.h, src/aws/compression/arrow/compress.h, plugins/out_s3/s3.h	Adds FLB_PARQUET_COMPRESSION_* constants; updates out_s3_compress_parquet signature to accept parquet_compression; adds FLB_S3_FORMAT_* constants and s3_format/parquet_compression fields.
Arrow Parquet codec implementation src/aws/compression/arrow/compress.c	Adds parquet_compression_to_garrow mapper; threads parquet_compression into table_to_parquet_buffer; builds GParquetWriterProperties with selected codec; improves error logging and cleanup; updates exported out_s3_compress_parquet.
S3 plugin Parquet integration plugins/out_s3/s3.c, plugins/out_s3/s3.h	Includes flb_aws_compress.h; adds parse_output_format and map_to_parquet_codec; initializes and parses s3_format/parquet_compression; deprecates compression=parquet and maps Parquet page codecs; runs Parquet conversion before upload and adjusts cleanup/error handling; updates config help text.
Parquet compression tests tests/internal/aws_compress.c	Adds FLB_HAVE_ARROW_PARQUET-guarded tests for SNAPPY, ZSTD, GZIP, NONE Parquet outputs; validates PAR1 magic markers and size behavior; registers tests and tidies minor test formatting.
Build configuration src/aws/flb_aws_compress.c	Adjusts preprocessor guard placement around Arrow-related compression option in the compression options array.

Sequence Diagram

sequenceDiagram
  participant Config as S3 Config
  participant S3Upload as S3 Upload Path
  participant ParquetLib as Parquet Conversion (out_s3_compress_parquet)
  participant ArrowWriter as Arrow/GParquet
  Config->>Config: parse format + compression (resolve parquet codec)
  S3Upload->>ParquetLib: out_s3_compress_parquet(json, size, &buf, &sz, codec)
  ParquetLib->>ArrowWriter: create writer with GParquetWriterProperties(codec)
  ArrowWriter-->>ParquetLib: parquet buffer
  ParquetLib-->>S3Upload: parquet buffer returned
  S3Upload->>S3Upload: upload buffer to S3

Loading

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• fluent/fluent-bit#10691: The main PR builds directly on #10691’s Parquet compression plumbing for the S3 output (same out_s3_compress_parquet/FLB_AWS_COMPRESS_*/out_s3 Parquet wiring) by extending it to support runtime page-level Parquet codecs and updating the function signature accordingly.
• fluent/fluent-bit#11762: Both PRs modify plugins/out_s3/s3.c/plugins/out_s3/s3.h to extend the S3 output plugin’s configurable format handling and enforce log_key constraints, but they target different format modes (Parquet page compression vs otlp_json).

Suggested reviewers

• edsiper
• cosmo0920
• fujimotos
• koleini

Poem

🐰 In a burrow of bytes I knit a parquet tune,

SNAPPY, GZIP, ZSTD — codecs hum by moon,
Pages snug with "PAR1" at start and end,
S3 carts the bundles, no data to mend,
I hop away happy — compressed and immune.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 36.84% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 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: adding Parquet format support with runtime-selectable page compression codecs to the S3 output plugin.
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.

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• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 4

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@plugins/out_s3/s3.c`:
- Around line 740-761: The Parquet path currently accepts a user-specified
log_key which later breaks Parquet conversion; in the FLB_S3_FORMAT_PARQUET
branch (the block that calls enable_parquet_format(ctx)) add a check after
enable_parquet_format succeeds: if ctx->log_key != NULL then call
flb_plg_error(ctx->ins, "'log_key' is not supported when format is parquet") and
return -1; use the existing symbols FLB_S3_FORMAT_PARQUET,
enable_parquet_format, ctx->log_key and ctx->ins to locate and implement the
check.
- Around line 1316-1331: The Parquet branch (out_s3_compress_parquet) allocates
payload_buf but later cleanup only frees when ctx->compression !=
FLB_AWS_COMPRESS_NONE, leaking payload_buf whenever ctx->compression was cleared
for Parquet; ensure payload_buf is independently freed whenever it was
allocated: after successful upload in the put_object path and in every
early-return/error path (including the FLB_RETRY path where s3_store_file_unlock
and chunk->failures are adjusted). Add a conditional free of payload_buf (e.g.,
flb_free(payload_buf) guarded by whether out_s3_compress_parquet set it) in the
out_s3_compress_parquet success branch and all subsequent exit points regardless
of ctx->compression.
- Around line 114-125: map_to_parquet_codec currently maps unknown compression
types to FLB_PARQUET_COMPRESSION_NONE which silently downgrades user config;
change map_to_parquet_codec to return a sentinel (e.g., -1) for unsupported
codecs and in the caller (where ctx->parquet_compression is set) check for -1,
call flb_plg_error(ctx->ins, "unsupported compression '%s' for format=parquet",
tmp) and return -1 to fail init, and only set ctx->compression =
FLB_AWS_COMPRESS_NONE after a successful mapping; reference map_to_parquet_codec
and ctx->parquet_compression for locating changes.

In `@tests/internal/aws_compress.c`:
- Around line 347-353: The test currently calls out_s3_compress_parquet and
always performs memcmp/out_size checks even if ret != 0, risking dereferencing
invalid out_buf or using out_size after a failed conversion; update the test
around the out_s3_compress_parquet call (and the analogous blocks testing other
compressions) to guard subsequent assertions by early-failing or skipping those
checks when ret != 0 (e.g., assert/require the conversion succeeded before using
out_buf/out_size, or return/continue the test case on failure), and ensure
out_buf is only dereferenced and flb_free'd when it was actually populated by a
successful call.

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• Create a new PR with the fixes

---

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Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 4502cf5b-2e0a-4cf0-86d5-02fb93b9e780

📥 Commits

Reviewing files that changed from the base of the PR and between 19cc8f9 and 000f6af.

📒 Files selected for processing (7)

• include/fluent-bit/aws/flb_aws_compress.h
• plugins/out_s3/s3.c
• plugins/out_s3/s3.h
• src/aws/compression/arrow/compress.c
• src/aws/compression/arrow/compress.h
• src/aws/flb_aws_compress.c
• tests/internal/aws_compress.c

💤 Files with no reviewable changes (1)

• src/aws/flb_aws_compress.c

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@plugins/out_s3/s3.c`:
- Around line 714-715: The default Parquet codec is being set to
FLB_PARQUET_COMPRESSION_NONE (ctx->parquet_compression) which causes plain
format=parquet to produce uncompressed output; change the default initialization
to FLB_PARQUET_COMPRESSION_SNAPPY so new default codec is Snappy, and preserve
backward compatibility by keeping the deprecated compression=parquet code path
(the branch that explicitly handles compression="parquet") to force
ctx->parquet_compression = FLB_PARQUET_COMPRESSION_NONE when that deprecated
option is used; update both the initializations around where ctx->s3_format is
set and the identical block later (the region referenced around lines 879-886)
so both locations use SNAPPY as the default and still override to NONE for the
deprecated path.
- Around line 879-886: The deprecated branch that treats "compression=parquet"
as an alias still enables Parquet without rejecting the log_key option; update
the block handling strcasecmp(tmp, "parquet") so it performs the same validation
as the new format guard: call the same check that rejects/validates log_key (the
logic used by enable_parquet_format or the code that inspects log_key) before
enabling Parquet, and if log_key is present return -1 (after emitting the
existing flb_plg_warn about deprecation) so the deprecated path cannot bypass
the log_key rejection; ensure you reference the same ctx/ins structures and
preserve the warning text via flb_plg_warn and the call to
enable_parquet_format(ctx).

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

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📒 Files selected for processing (6)

• e2e-tests.txt
• fluent-bit.iml
• plugins/out_s3/s3.c
• plugins/out_s3/s3.h
• src/aws/compression/arrow/compress.c
• tests/internal/aws_compress.c

✅ Files skipped from review due to trivial changes (1)

• fluent-bit.iml

🚧 Files skipped from review as they are similar to previous changes (3)

• plugins/out_s3/s3.h
• src/aws/compression/arrow/compress.c
• tests/internal/aws_compress.c