Add max baggage length as limitation by XSAM · Pull Request #8222 · open-telemetry/opentelemetry-go

XSAM · 2026-04-17T00:13:48Z

goos: darwin
goarch: arm64
pkg: go.opentelemetry.io/otel/baggage
cpu: Apple M1 Max
                  │      old.txt      │               new.txt                │
                  │      sec/op       │   sec/op     vs base                 │
ParseOversized-10   23409245.5n ± 14%   133.2n ± 3%  -100.00% (p=0.000 n=10)

                  │    old.txt     │              new.txt               │
                  │      B/op      │    B/op     vs base                │
ParseOversized-10   801099.00 ± 0%   88.00 ± 0%  -99.99% (p=0.000 n=10)

                  │     old.txt     │               new.txt               │
                  │    allocs/op    │ allocs/op   vs base                 │
ParseOversized-10   250007.000 ± 0%   3.000 ± 0%  -100.00% (p=0.000 n=10)

codecov · 2026-04-17T00:16:16Z

Codecov Report

❌ Patch coverage is 94.73684% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.9%. Comparing base (4086701) to head (c782fa6).

Files with missing lines	Patch %	Lines
propagation/baggage.go	93.3%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #8222   +/-   ##
=====================================
  Coverage   82.9%   82.9%           
=====================================
  Files        314     314           
  Lines      24985   25019   +34     
=====================================
+ Hits       20730   20760   +30     
- Misses      3882    3884    +2     
- Partials     373     375    +2

Files with missing lines	Coverage Δ
baggage/baggage.go	`98.7% <100.0%> (-0.8%)`	⬇️
propagation/baggage.go	`94.0% <93.3%> (-1.0%)`	⬇️

... and 1 file with indirect coverage changes

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Copilot

Pull request overview

Adds stricter enforcement of W3C Baggage size limits across parsing (baggage) and extraction (propagation), and reduces overhead/error verbosity for malformed inputs.

Changes:

Enforce an 8192-byte maximum baggage string size in baggage.Parse, and cap joined parse errors to a fixed maximum.
Add an aggregate byte budget guard when extracting from multiple baggage header values in the propagator.
Update/add tests and a benchmark to cover oversized inputs and aggregate-budget behavior, plus a changelog entry.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
`propagation/baggage.go`	Adds aggregate byte budget limit when processing multiple baggage header values.
`propagation/baggage_test.go`	Updates expectations for aggregate-budget behavior and adds new extraction tests.
`baggage/baggage.go`	Adds max-size early rejection and caps how many parse errors are joined.
`baggage/baggage_test.go`	Updates parse tests for new oversize behavior; adds benchmark and error-cap test.
`CHANGELOG.md`	Adds a release note about the baggage parsing/extraction change.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…o into fix/baggage-parsing

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

MrAlias

Thanks for tightening the aggregate-size handling here. I think there is one edge case left around repeated baggage headers where the combined wire value can still exceed the intended limit. I left an inline note on the specific check with the concrete case and the adjustment that should make the enforcement consistent.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

…o fix/baggage-parsing-review

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

pellared · 2026-04-29T11:34:50Z

Can you add both benchmark and benchstat results to the PR description?

…o into fix/baggage-parsing

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

+		if totalBytes > maxBytesPerBaggageString {
+			parseErrors++
+			if parseErrors <= maxParseErrors {


XSAM · 2026-05-06T00:08:53Z

 	b, err := baggage.New(members...)
 	if err != nil {
-		errorhandler.GetErrorHandler().Handle(err)
+		truncateErr = errors.Join(truncateErr, err)


Loading additional members after the whole header has exceeded the limit requires more memory allocation. I think this is a trade-off: our last-one-wins is a best-effort promise when facing oversized baggage.

+// If the raw baggage-string exceeds the maximum allowed bytes (8192), an
+// empty Baggage and an error are returned. If adding valid members would
+// cause the parsed baggage to exceed the maximum allowed bytes (8192), or if
+// the baggage-string exceeds the maximum allowed members (64), parsing stops
+// and an error is returned along with the partial result.


pellared · 2026-05-05T13:55:59Z

+			if uw, ok := err.(interface{ Unwrap() []error }); ok {
+				parseErrors += len(uw.Unwrap())
+			} else {
+				parseErrors++
+			}
+			if parseErrors <= maxParseErrors {
+				truncateErr = errors.Join(truncateErr, err)
+			}


If one header value returns a capped joined error from baggage.Parse, extractMultiBaggage counts len(Unwrap()) and may drop that error entirely once it crosses maxParseErrors, then only emits and 1 more error(s).

The existing propagation test covers many invalid headers, not one header with many invalid members.

Re-introducing max baggage length

05a5c11

XSAM requested review from MrAlias, dashpole, dmathieu, flc1125 and pellared as code owners April 17, 2026 00:13

XSAM marked this pull request as draft April 17, 2026 00:21

XSAM added 4 commits April 16, 2026 22:49

Fix lint

128f3c1

Update CHANGELOG

c274c8e

Merge branch 'main' into fix/baggage-parsing

5eb9558

Fix CHANGELOG

f3bcf1a

XSAM marked this pull request as ready for review April 17, 2026 06:23

pellared requested a review from Copilot April 17, 2026 07:11

Copilot started reviewing on behalf of pellared April 17, 2026 07:11 View session

Copilot AI reviewed Apr 17, 2026

View reviewed changes

Comment thread baggage/baggage.go

Comment thread propagation/baggage_test.go

Comment thread CHANGELOG.md Outdated

Comment thread propagation/baggage.go Outdated

Comment thread propagation/baggage.go

XSAM and others added 8 commits April 21, 2026 12:55

Update CHANGELOG.md

1bf7210

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Apply suggestion

6feee46

Remove hardcoded 8192 in test cases

4030ecd

Enforce maxParseErrors for extractMultiBaggage

f155676

Merge branch 'main' into fix/baggage-parsing

64cf1f1

Fix linter

9ea953d

Merge branch 'fix/baggage-parsing' of github.com:XSAM/opentelemetry-g…

98da4b3

…o into fix/baggage-parsing

Fix markdown

55e5b4f

MrAlias requested a review from Copilot April 22, 2026 21:09

Copilot started reviewing on behalf of MrAlias April 22, 2026 21:09 View session

Copilot AI reviewed Apr 22, 2026

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Comment thread propagation/baggage.go Outdated

Comment thread propagation/baggage.go

Comment thread baggage/baggage.go Outdated

MrAlias reviewed Apr 22, 2026

View reviewed changes

Comment thread propagation/baggage.go

dashpole reviewed Apr 23, 2026

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Comment thread propagation/baggage.go Outdated

MrAlias added this to the v1.44.0 milestone Apr 23, 2026

XSAM and others added 2 commits April 28, 2026 13:58

Update baggage/baggage.go

285423e

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Merge branch 'main' of github.com:open-telemetry/opentelemetry-go int…

35b72da

…o fix/baggage-parsing-review

XSAM force-pushed the fix/baggage-parsing branch from 285423e to 55e5b4f Compare April 28, 2026 21:06

Count comma separator between combined header values

1c8caf8

pellared requested review from MrAlias, Copilot and dashpole April 28, 2026 21:25

Copilot started reviewing on behalf of pellared April 28, 2026 21:26 View session

Fix linter

832c87b

Copilot AI reviewed Apr 28, 2026

View reviewed changes

Comment thread propagation/baggage.go

Comment thread propagation/baggage_test.go Outdated

Update propagation/baggage_test.go

1424a1c

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

pellared reviewed Apr 29, 2026

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Comment thread CHANGELOG.md Outdated

pellared reviewed Apr 29, 2026

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Comment thread baggage/baggage_test.go Outdated

Comment thread propagation/baggage.go Outdated

XSAM added 3 commits April 29, 2026 16:25

Apply suggestions

df9b633

Merge branch 'fix/baggage-parsing' of github.com:XSAM/opentelemetry-g…

0f14624

…o into fix/baggage-parsing

Merge branch 'main' into fix/baggage-parsing

3bdee54

pellared reviewed Apr 30, 2026

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Comment thread propagation/baggage.go Outdated

pellared requested a review from Copilot April 30, 2026 13:43

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Comment thread propagation/baggage.go Outdated

XSAM and others added 4 commits April 30, 2026 18:04

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36456d1

Merge branch 'main' into fix/baggage-parsing

d9d8cd2

Fix CHANGELOG format

965ba68

Merge branch 'main' into fix/baggage-parsing

c782fa6

pellared requested a review from Copilot May 4, 2026 20:22

Copilot started reviewing on behalf of pellared May 4, 2026 20:23 View session

Copilot AI reviewed May 4, 2026

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pellared reviewed May 5, 2026

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