feat: server action logging by huozhi · Pull Request #88277 · vercel/next.js

huozhi · 2026-01-08T14:45:49Z

Inrtoduce logging for server actions in dev mode, displaying function name, arguments, status code, duration, and file location.

Log format:

POST / 200 in 300ms
└─ ƒ successAction(5) in 1ms app/actions.ts
POST / 200 in 300ms
└─ ƒ redirectAction("/target") in 0ms app/actions.ts
POST / 200 in 300ms
└─ ƒ errorAction() in 2ms app/actions.ts

The Rust SWC transform captures source location (line/column) when processing server actions and embeds it in the action metadata comment. At runtime of next dev, the action handler extracts the function name, formats arguments measures execution time, and determines the status code. The log is emitted in a finally {} block with ANSI color codes for the status (aligned with normal request logging) and the file path normalized relative to the project root.

nextjs-bot · 2026-01-08T14:46:20Z

Allow CI Workflow Run

approve CI run for commit: 592da9e

Note: this should only be enabled once the PR is ready to go and can only be enabled by a maintainer

nextjs-bot · 2026-01-08T14:55:57Z

Tests Passed

codspeed-hq · 2026-01-08T15:10:10Z

Merging this PR will not alter performance

✅ 17 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing server-action-logging (cc3e651) with canary (43460b1)}

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

nextjs-bot · 2026-01-08T15:12:55Z

Stats from current PR

🔴 1 regression, 2 improvements

Metric	Canary	PR	Change	Trend
node_modules Size	458 MB	458 MB	🔴 +274 kB (+0%)	▁▁▁▁▁
Turbo Build Time	4.330s	4.041s	🟢 289ms (-7%)	▁▃▁▁█
Turbo Build Time (cached)	4.388s	4.088s	🟢 300ms (-7%)	▁▃▁▁█

📊 All Metrics

📖 Metrics Glossary

Dev Server Metrics:

Listen = TCP port starts accepting connections
First Request = HTTP server returns successful response
Cold = Fresh build (no cache)
Warm = With cached build artifacts

Build Metrics:

Fresh = Clean build (no .next directory)
Cached = With existing .next directory

Change Thresholds:

Time: Changes < 50ms AND < 10%, OR < 2% are insignificant
Size: Changes < 1KB AND < 1% are insignificant
All other changes are flagged to catch regressions

⚡ Dev Server

Metric	Canary	PR	Change	Trend
Cold (Listen)	455ms	455ms	✓	▁▁▁▁█
Cold (Ready in log)	439ms	439ms	✓	▂▁▂▂█
Cold (First Request)	1.196s	1.135s	✓	▄▂▄▄█
Warm (Listen)	456ms	456ms	✓	▁▁▁▁█
Warm (Ready in log)	443ms	443ms	✓	▁▁▁▁█
Warm (First Request)	341ms	341ms	✓	▁▂▁▁█

📦 Dev Server (Webpack) (Legacy)

📦 Dev Server (Webpack)

Metric	Canary	PR	Change	Trend
Cold (Listen)	505ms	506ms	✓	▁▁▁▁▁
Cold (Ready in log)	461ms	462ms	✓	▁▁▇▆▁
Cold (First Request)	1.882s	1.872s	✓	▁▁▅▅▂
Warm (Listen)	505ms	459ms	✓	▁▁▁▁▁
Warm (Ready in log)	459ms	460ms	✓	▁▁▅▅▁
Warm (First Request)	1.885s	1.896s	✓	▁▁▅▅▁

⚡ Production Builds

Metric	Canary	PR	Change	Trend
Fresh Build	4.330s	4.041s	🟢 289ms (-7%)	▁▃▁▁█
Cached Build	4.388s	4.088s	🟢 300ms (-7%)	▁▃▁▁█

📦 Production Builds (Webpack) (Legacy)

📦 Production Builds (Webpack)

Metric	Canary	PR	Change	Trend
Fresh Build	14.489s	14.393s	✓	▁▁▃▃▄
Cached Build	14.493s	14.495s	✓	▂▁▃▃▃
node_modules Size	458 MB	458 MB	🔴 +274 kB (+0%)	▁▁▁▁▁

📦 Bundle Sizes

Bundle Sizes

⚡ Turbopack

Client

Main Bundles: **430 kB** → **431 kB** ⚠️ +680 B

82 files with content-based hashes (individual files not comparable between builds)

Server

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	790 B	792 B	✓
Total	790 B	792 B	⚠️ +2 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	449 B	450 B	✓
Total	449 B	450 B	⚠️ +1 B

📦 Webpack

Client

Main Bundles

	Canary	PR	Change
2086.HASH.js gzip	169 B	N/A	-
2161-HASH.js gzip	5.41 kB	N/A	-
2747-HASH.js gzip	4.48 kB	N/A	-
4322-HASH.js gzip	52.3 kB	N/A	-
ec793fe8-HASH.js gzip	62.3 kB	N/A	-
framework-HASH.js gzip	59.8 kB	59.8 kB	✓
main-app-HASH.js gzip	252 B	254 B	✓
main-HASH.js gzip	38.6 kB	39 kB	🔴 +423 B (+1%)
webpack-HASH.js gzip	1.68 kB	1.68 kB	✓
1596.HASH.js gzip	N/A	169 B	-
2658-HASH.js gzip	N/A	52.7 kB	-
6349-HASH.js gzip	N/A	4.46 kB	-
7019-HASH.js gzip	N/A	5.43 kB	-
b17a3386-HASH.js gzip	N/A	62.3 kB	-
Total	225 kB	226 kB	⚠️ +769 B

Polyfills

	Canary	PR	Change
polyfills-HASH.js gzip	39.4 kB	39.4 kB	✓
Total	39.4 kB	39.4 kB	✓

Pages

	Canary	PR	Change
_app-HASH.js gzip	194 B	193 B	✓
_error-HASH.js gzip	182 B	182 B	✓
css-HASH.js gzip	336 B	335 B	✓
dynamic-HASH.js gzip	1.8 kB	1.8 kB	✓
edge-ssr-HASH.js gzip	256 B	256 B	✓
head-HASH.js gzip	352 B	349 B	✓
hooks-HASH.js gzip	385 B	384 B	✓
image-HASH.js gzip	580 B	580 B	✓
index-HASH.js gzip	259 B	258 B	✓
link-HASH.js gzip	2.5 kB	2.51 kB	✓
routerDirect..HASH.js gzip	319 B	317 B	✓
script-HASH.js gzip	385 B	387 B	✓
withRouter-HASH.js gzip	316 B	315 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Total	7.97 kB	7.96 kB	✅ -8 B

Server

Edge SSR

	Canary	PR	Change
edge-ssr.js gzip	125 kB	125 kB	✓
page.js gzip	242 kB	242 kB	✓
Total	366 kB	367 kB	⚠️ +572 B

Middleware

	Canary	PR	Change
middleware-b..fest.js gzip	653 B	653 B	✓
middleware-r..fest.js gzip	155 B	156 B	✓
middleware.js gzip	33 kB	33.2 kB	✓
edge-runtime..pack.js gzip	842 B	842 B	✓
Total	34.6 kB	34.9 kB	⚠️ +273 B

Build Details

Build Manifests

	Canary	PR	Change
_buildManifest.js gzip	738 B	738 B	✓
Total	738 B	738 B	✓

Build Cache

	Canary	PR	Change
0.pack gzip	3.66 MB	3.67 MB	🔴 +12.3 kB (+0%)
index.pack gzip	99.2 kB	99.8 kB	✓
index.pack.old gzip	100 kB	100 kB	✓
Total	3.86 MB	3.87 MB	⚠️ +12.6 kB

🔄 Shared (bundler-independent)

Runtimes

	Canary	PR	Change
app-page-exp...dev.js gzip	303 kB	304 kB	✓
app-page-exp..prod.js gzip	158 kB	158 kB	✓
app-page-tur...dev.js gzip	303 kB	304 kB	✓
app-page-tur..prod.js gzip	158 kB	158 kB	✓
app-page-tur...dev.js gzip	300 kB	301 kB	✓
app-page-tur..prod.js gzip	156 kB	156 kB	✓
app-page.run...dev.js gzip	300 kB	301 kB	✓
app-page.run..prod.js gzip	156 kB	156 kB	✓
app-route-ex...dev.js gzip	68.8 kB	68.8 kB	✓
app-route-ex..prod.js gzip	47.6 kB	47.6 kB	✓
app-route-tu...dev.js gzip	68.8 kB	68.8 kB	✓
app-route-tu..prod.js gzip	47.6 kB	47.6 kB	✓
app-route-tu...dev.js gzip	68.4 kB	68.4 kB	✓
app-route-tu..prod.js gzip	47.4 kB	47.4 kB	✓
app-route.ru...dev.js gzip	68.4 kB	68.4 kB	✓
app-route.ru..prod.js gzip	47.3 kB	47.3 kB	✓
dist_client_...dev.js gzip	324 B	324 B	✓
dist_client_...dev.js gzip	326 B	326 B	✓
dist_client_...dev.js gzip	318 B	318 B	✓
dist_client_...dev.js gzip	317 B	317 B	✓
pages-api-tu...dev.js gzip	41.2 kB	41.2 kB	✓
pages-api-tu..prod.js gzip	31.3 kB	31.3 kB	✓
pages-api.ru...dev.js gzip	41.1 kB	41.1 kB	✓
pages-api.ru..prod.js gzip	31.2 kB	31.2 kB	✓
pages-turbo....dev.js gzip	50.8 kB	50.8 kB	✓
pages-turbo...prod.js gzip	38.2 kB	38.2 kB	✓
pages.runtim...dev.js gzip	50.7 kB	50.7 kB	✓
pages.runtim..prod.js gzip	38.2 kB	38.2 kB	✓
server.runti..prod.js gzip	62.2 kB	62.2 kB	✓
Total	2.69 MB	2.69 MB	⚠️ +4.81 kB

📝 Changed Files (9 files)

Files with changes:

app-page-exp..ntime.dev.js
app-page-exp..time.prod.js
app-page-tur..ntime.dev.js
app-page-tur..time.prod.js
app-page-tur..ntime.dev.js
app-page-tur..time.prod.js
app-page.runtime.dev.js
app-page.runtime.prod.js
server.runtime.prod.js

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timneutkens

It was a bit unclear to me if it's now generating the source information in production as well (that shouldn't happen), is it correctly doing this only in development? Then it looks good to me 💯

huozhi · 2026-01-16T12:39:26Z

It was a bit unclear to me if it's now generating the source information in production as well (that shouldn't happen), is it correctly doing this only in development? Then it looks good to me 💯

in test/e2e/app-dir/server-action-logging/server-action-logging.test.ts we have test that it's logging in the production. The transform still work but it's only changing the comment in the code, and will be erased by minification

Server Function logging (#88277) is now opt-in, consistent with how fetch logging works. This reduces noise in development logs by default. Additionally, for `'use cache'` Server Functions called from the client, the logging needs more work to be useful. Keeping it opt-in avoids exposing incomplete functionality by default. Server Function logging can be enabled in `next.config.js`: ```js module.exports = { logging: { serverFunctions: true, }, } ```

nextjs-bot added created-by: Next.js team PRs by the Next.js team. tests Turbopack Related to Turbopack with Next.js. type: next labels Jan 8, 2026

huozhi force-pushed the server-action-logging branch from 592da9e to 837c569 Compare January 8, 2026 14:48

huozhi force-pushed the server-action-logging branch 2 times, most recently from 7ca65c3 to d8c7379 Compare January 9, 2026 22:45

huozhi marked this pull request as ready for review January 12, 2026 13:07

huozhi requested review from feedthejim, gaojude, ijjk and mischnic January 12, 2026 14:24

gaojude requested a review from timneutkens January 13, 2026 17:00

huozhi added 13 commits January 13, 2026 18:42

server action logging

7d3adcd

format, location and status

86eb7af

add test

8d17e0d

update export info

bb22753

normalize proj path

685cafe

update transform snapshot

c214c90

update snap

8e2d761

cargo fmt

03ea00f

cargo

728c168

refactor util and test

ebbf7c4

test case

83d5ec9

rm part

3116edf

fix serializer

d36c81b

huozhi added 2 commits January 13, 2026 18:42

update test snapshot

4a1f1b4

nested logging

65a20e5

huozhi force-pushed the server-action-logging branch from fb95200 to 65a20e5 Compare January 13, 2026 17:43

huozhi added 3 commits January 13, 2026 18:59

leading space

ad9e6ed

keep actions in request meta and log together

3c6ea43

update test snapshot

16593fe

timneutkens approved these changes Jan 16, 2026

View reviewed changes

huozhi added 2 commits January 16, 2026 14:26

revert loc consume

dbc4480

cargo fmt

cc3e651

huozhi merged commit 3aad67b into canary Jan 16, 2026
289 of 291 checks passed

huozhi deleted the server-action-logging branch January 16, 2026 14:09

wyattjoh pushed a commit that referenced this pull request Jan 16, 2026

feat: server action logging (#88277)

1378196

unstubbable mentioned this pull request Jan 30, 2026

Make Server Function logging opt-in via logging.serverFunctions #89321

Merged

github-actions bot added the locked label Jan 31, 2026

github-actions bot locked as resolved and limited conversation to collaborators Jan 31, 2026

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feat: server action logging#88277

feat: server action logging#88277
huozhi merged 20 commits intocanaryfrom
server-action-logging

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🔴 1 regression, 2 improvements

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