Support for gzip compression in OTLP exporter by hannahhaering · Pull Request #6494 · open-telemetry/opentelemetry-dotnet

hannahhaering · 2025-09-11T19:27:52Z

Implements #3961

Changes

Added support for gzip compression to the OTLP exporter (HTTP and gRPC)
Compression can be enabled via configuration/environment variables as per specification
The first 5 bytes of gRPC messages have previously been created in the corresponding (Log, Trace, Metrics) exporter, centralized this in the ExportClient
Added new tests for HTTP and gRPC export, with and without compression
Extended the configuration tests to cover the new, compression related options

Validation/Testing

Used the OpenTelemetry example Console application with compression enabled.
Verified that traces were successfully exported to the OpenTelemetry Collector using both HTTP and gRPC, with gzip compression enabled.
Confirmed that traces appeared correctly when routed through the collector.
Verified that disabling compression continues to work as before.

Merge requirement checklist

CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
Unit tests added/updated
Appropriate CHANGELOG.md files updated for non-trivial changes
Changes in public API reviewed (if applicable)

…port client

codecov · 2025-09-11T19:35:56Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.83%. Comparing base (353bc85) to head (41dc747).
⚠️ Report is 228 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6494      +/-   ##
==========================================
+ Coverage   86.63%   86.83%   +0.20%     
==========================================
  Files         258      258              
  Lines       11878    11907      +29     
==========================================
+ Hits        10290    10340      +50     
+ Misses       1588     1567      -21

Flag	Coverage Δ
unittests-Project-Experimental	`86.46% <100.00%> (-0.09%)`	⬇️
unittests-Project-Stable	`86.77% <100.00%> (+0.25%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ol/Implementation/ExportClient/OtlpExportClient.cs	`100.00% <100.00%> (ø)`
...mplementation/ExportClient/OtlpGrpcExportClient.cs	`79.24% <100.00%> (+3.96%)`	⬆️
...mplementation/ExportClient/OtlpHttpExportClient.cs	`100.00% <100.00%> (ø)`
...orter.OpenTelemetryProtocol/OtlpExporterOptions.cs	`99.15% <100.00%> (+0.06%)`	⬆️
....Exporter.OpenTelemetryProtocol/OtlpLogExporter.cs	`88.00% <ø> (-1.66%)`	⬇️
...porter.OpenTelemetryProtocol/OtlpMetricExporter.cs	`77.27% <ø> (-3.50%)`	⬇️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	`87.50% <ø> (-1.79%)`	⬇️

... and 6 files with indirect coverage changes

rajkumar-rangaraj · 2025-09-15T17:42:06Z

@hannahhaering The OTLP Exporter currently lacks integration tests. With your proposed changes, did you test them with telemetry systems, and what were the results? Please update the PR description to include more details about how you tested with the collector or other services. It would be beneficial to verify with multiple sources.

…ahhaering/opentelemetry-dotnet into add-compression-in-exporter

…pcMessageHandler.cs Co-authored-by: Martin Costello <martin@martincostello.com>

…Options.cs Co-authored-by: Martin Costello <martin@martincostello.com>

…pression.cs Co-authored-by: Martin Costello <martin@martincostello.com>

…ahhaering/opentelemetry-dotnet into add-compression-in-exporter

github-actions · 2025-09-27T03:19:42Z

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github-actions · 2025-10-07T03:21:28Z

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github-actions · 2025-10-15T03:26:31Z

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rajkumar-rangaraj · 2025-12-03T20:24:48Z

        }

-        // TODO: Support compression.
+        Stream data = new MemoryStream(buffer, 0, contentLength);


The change from ByteArrayContent to MemoryStream + StreamContent introduces a performance regression for the non-compressed path.
When compression is not enabled (which is the default), we're adding an extra allocation per export (2 objects vs. 1 previously). This is a hot path executed on every export batch.
Users who haven't opted into compression should not pay this cost.

rajkumar-rangaraj

We should also explore if compression can be achieved without the additional allocation overhead (e.g., compress directly to network stream, pooled buffers).

Referece: https://github.com/open-telemetry/opentelemetry-dotnet/pull/6494/files#r2586506032

github-actions · 2025-12-20T03:34:22Z

This PR was marked stale due to lack of activity and will be closed in 7 days. Commenting or pushing will instruct the bot to automatically remove the label. This bot runs once per day.

github-actions · 2025-12-28T03:47:34Z

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github-actions · 2026-01-04T03:48:09Z

Closed as inactive. Feel free to reopen if this PR is still being worked on.

Add support for GZip compression to the OTLP exporter. Picks up from open-telemetry#6494. Resolves open-telemetry#3961. Co-Authored-By: Hannah Haering <157852144+hannahhaering@users.noreply.github.com>

hannahhaering added 9 commits September 5, 2025 22:46

implement gzip compression in exporter

5c729a2

add missing property in IOtlpExporterOptions

cc0757d

fix failed tests

2efddd6

added tests for compression; moved grpc header from exporters into ex…

56fd60a

…port client

removed comments

9cd706b

add test

b7a5d61

Merge remote-tracking branch 'origin' into add-compression-in-exporter

faf407b

fix dataLength

39d6187

Updated public API files

fa128af

github-actions Bot added the pkg:OpenTelemetry.Exporter.OpenTelemetryProtocol Issues related to OpenTelemetry.Exporter.OpenTelemetryProtocol NuGet package label Sep 11, 2025

added changelog entry for compression in exporter

8449eb5

hannahhaering and others added 2 commits September 11, 2025 16:00

fix spacing

e720418

Merge branch 'main' into add-compression-in-exporter

b62d445

hannahhaering marked this pull request as ready for review September 11, 2025 20:20

hannahhaering requested a review from a team as a code owner September 11, 2025 20:20

martincostello reviewed Sep 12, 2025

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alanwest reviewed Sep 16, 2025

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Comment thread src/OpenTelemetry.Exporter.OpenTelemetryProtocol/.publicApi/Stable/PublicAPI.Unshipped.txt Outdated

hannahhaering and others added 5 commits September 16, 2025 21:35

Merge remote-tracking branch 'origin' into add-compression-in-exporter

07bb383

Merge branch 'add-compression-in-exporter' of https://github.com/hann…

24c723a

…ahhaering/opentelemetry-dotnet into add-compression-in-exporter

Introduced enum for export compression configuration

e71f472

Update test/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests/TestGr…

2b869ae

…pcMessageHandler.cs Co-authored-by: Martin Costello <martin@martincostello.com>

use streams in compression method

1e60db8

martincostello reviewed Sep 18, 2025

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hannahhaering and others added 4 commits September 18, 2025 22:08

Update src/OpenTelemetry.Exporter.OpenTelemetryProtocol/IOtlpExporter…

d30fa88

…Options.cs Co-authored-by: Martin Costello <martin@martincostello.com>

Update src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExportCom…

4ddd75e

…pression.cs Co-authored-by: Martin Costello <martin@martincostello.com>

split unit tests by compression; added grpc compression header

047044e

Merge branch 'add-compression-in-exporter' of https://github.com/hann…

b017a59

…ahhaering/opentelemetry-dotnet into add-compression-in-exporter

martincostello approved these changes Sep 19, 2025

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Comment thread ...Telemetry.Exporter.OpenTelemetryProtocol/Implementation/ExportClient/OtlpGrpcExportClient.cs Outdated

Comment thread src/OpenTelemetry.Exporter.OpenTelemetryProtocol/OtlpExportCompression.cs Outdated

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martincostello mentioned this pull request Apr 10, 2026

[OTLP] Add support for GZip compression #7055

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