collect and propagate process tags in first chunk span by tlhunter · Pull Request #6733 · DataDog/dd-trace-js

tlhunter · 2025-10-23T22:21:28Z

What does this PR do?

Motivation

assists with service renaming

Plugin Checklist

Additional Notes

github-actions · 2025-10-23T22:22:08Z

Overall package size

Self size: 13.64 MB
Deduped: 113.83 MB
No deduping: 128.85 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | @datadog/libdatadog | 0.7.0 | 35.02 MB | 35.02 MB | | @datadog/native-appsec | 10.3.0 | 20.73 MB | 20.74 MB | | @datadog/pprof | 5.12.0 | 11.19 MB | 11.57 MB | | @datadog/native-iast-taint-tracking | 4.1.0 | 9.01 MB | 9.02 MB | | @opentelemetry/resources | 1.30.1 | 557.67 kB | 7.71 MB | | @opentelemetry/core | 1.30.1 | 908.66 kB | 7.16 MB | | protobufjs | 7.5.4 | 2.95 MB | 5.83 MB | | @datadog/wasm-js-rewriter | 5.0.1 | 2.82 MB | 3.53 MB | | @datadog/native-metrics | 3.1.1 | 1.02 MB | 1.43 MB | | @opentelemetry/api-logs | 0.208.0 | 199.48 kB | 1.42 MB | | @opentelemetry/api | 1.9.0 | 1.22 MB | 1.22 MB | | jsonpath-plus | 10.3.0 | 617.18 kB | 1.08 MB | | import-in-the-middle | 1.15.0 | 127.66 kB | 856.24 kB | | lru-cache | 10.4.3 | 804.3 kB | 804.3 kB | | @datadog/openfeature-node-server | 0.2.0 | 118.51 kB | 437.19 kB | | opentracing | 0.14.7 | 194.81 kB | 194.81 kB | | source-map | 0.7.6 | 185.63 kB | 185.63 kB | | pprof-format | 2.2.1 | 163.06 kB | 163.06 kB | | @datadog/sketches-js | 2.1.1 | 109.9 kB | 109.9 kB | | @isaacs/ttlcache | 2.1.3 | 90.79 kB | 90.79 kB | | lodash.sortby | 4.7.0 | 75.76 kB | 75.76 kB | | ignore | 7.0.5 | 63.38 kB | 63.38 kB | | istanbul-lib-coverage | 3.2.2 | 34.37 kB | 34.37 kB | | rfdc | 1.4.1 | 27.15 kB | 27.15 kB | | dc-polyfill | 0.1.10 | 26.73 kB | 26.73 kB | | tlhunter-sorted-set | 0.1.0 | 24.94 kB | 24.94 kB | | shell-quote | 1.8.3 | 23.74 kB | 23.74 kB | | limiter | 1.1.5 | 23.17 kB | 23.17 kB | | retry | 0.13.1 | 18.85 kB | 18.85 kB | | semifies | 1.0.0 | 15.84 kB | 15.84 kB | | jest-docblock | 29.7.0 | 8.99 kB | 12.76 kB | | crypto-randomuuid | 1.0.0 | 11.18 kB | 11.18 kB | | ttl-set | 1.0.0 | 4.61 kB | 9.69 kB | | mutexify | 1.4.0 | 5.71 kB | 8.74 kB | | path-to-regexp | 0.1.12 | 6.6 kB | 6.6 kB | | module-details-from-path | 1.0.4 | 3.96 kB | 3.96 kB | | escape-string-regexp | 5.0.0 | 3.66 kB | 3.66 kB |

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

codecov · 2025-10-23T22:22:15Z

Codecov Report

❌ Patch coverage is 96.96970% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.81%. Comparing base (b95a717) to head (72ae510).
⚠️ Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
packages/dd-trace/src/span_format.js	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6733      +/-   ##
==========================================
+ Coverage   84.80%   84.81%   +0.01%     
==========================================
  Files         514      515       +1     
  Lines       21987    22015      +28     
==========================================
+ Hits        18645    18673      +28     
  Misses       3342     3342

☔ View full report in Codecov by Sentry.
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datadog-datadog-prod-us1 · 2025-10-23T22:23:59Z

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

_{This comment will be updated automatically if new data arrives.

* Fix with Cursor requires Datadog plugin ≥v2.17.0

🔗 Commit SHA: 72ae510 | Docs | Datadog PR Page | Was this helpful? Give us feedback!}

pr-commenter · 2025-10-23T22:39:22Z

Benchmarks

Benchmark execution time: 2025-12-09 23:36:10

Comparing candidate commit 72ae510 in PR branch tlhunter/process-tags with baseline commit b95a717 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 289 metrics, 31 unstable metrics.

dubloom

Small comments !

dubloom · 2025-11-21T10:40:53Z

+function sanitize (value) {
+  return String(value)
+    .toLowerCase()
+    .replaceAll(/[^a-zA-Z0-9/_.-]+/g, '_')


It's not written in the RFC, but I think : is also an authorized character

It looks like today we decided to disallow : characters to not disrupt key/value parsing.

Just to verify, has the RFC been updated to reflect everything here?

Yes: https://docs.google.com/document/d/1AFdLUuVk70i0bJd5335-RxqsvwAV9ovAqcO2z5mEMbA/edit?pli=1&tab=t.0#heading=h.t8ah57xwikx1

dubloom · 2025-11-21T10:42:41Z

+    this._processTags = config.propagateProcessTags?.enabled
+      ? getProcessTags().serialized
+      : false


How much can you expose global constants ? process tags will not change during the lifetime of the program. What we do in python is we exposed a constant (which is None or the value depending of the config) and the other modules can grab this constant (which also prevents recomputing the process tags several times)

It's easily achievable but is considered a "sin" in Node.js to create globals. However we can essentially have "namespaced globals" by exporting a singleton instance in a file (module) and requiring that file elsewhere.

That said the way I've set up the code we should only ever calculate the process tags a single time for the lifetime of the process so it does benefit from the never-changing behavior of process tags.

dubloom · 2025-11-21T10:54:13Z

+  const tags = [
+    // the immediate parent directory name of the entrypoint script, e.g. /foo/bar/baz/banana.js -> baz
+    ['entrypoint.basedir', ENTRYPOINT_PATH === '' ? undefined : path.basename(path.dirname(ENTRYPOINT_PATH))],
+
+    // the entrypoint script filename without the extension, e.g. /foo/bar/baz/banana.js -> banana
+    ['entrypoint.name', path.basename(ENTRYPOINT_PATH, path.extname(ENTRYPOINT_PATH)) || undefined],
+
+    // always script for JavaScript applications
+    ['entrypoint.type', 'script'],
+
+    // last segment of the current working directory, e.g. /foo/bar/baz/ -> baz
+    ['entrypoint.workdir', path.basename(CURRENT_WORKING_DIRECTORY) || undefined],
+
+    // the .name field from the application's package.json
+    ['package.json.name', pkg.name || undefined]
+  ]


Can this code throw ? It seems it's not the case but wanted to double check

In all my testing I only found a situation where require.main.filename could throw as require.main is missing in certain situations where the tracer is used in CI during test runs but I addressed that. Based on where this code is placed it should be running in nearly all of our CI jobs and those aren't failing.

PTO

tlhunter · 2025-12-02T16:52:19Z

Apparently the network requests have 3 layers instead of 2. There's the outer network request, which contains an array of "chunks", which contains an array of spans. Chunks contain all the spans related to a single trace. Currently the code is written to assume a chunk is synonymous with a network request.

We only need to send this data in the first span of the first chunk of the network request. That means this PR in its current form is sending redundant data. It's not the end of the world and is mergeable but I'll be working on removing the redundancy.

bengl

You'll also need to make the linter happy.

bengl · 2025-12-09T18:36:22Z

+  // Add process tags to the first span of the first trace in a payload
+  if (shouldAddProcessTags && processTags && span.meta) {
+    const { TRACING_FIELD_NAME } = require('./process-tags')
+    span.meta[TRACING_FIELD_NAME] = processTags


Seems to me that all this should be done in span_format.js, no?

I reverted all the changes in this file

bengl · 2025-12-09T18:40:29Z

+function sanitize (value) {
+  return String(value)
+    .toLowerCase()
+    .replaceAll(/[^a-zA-Z0-9/_.-]+/g, '_')


Just to verify, has the RFC been updated to reflect everything here?

bengl · 2025-12-09T18:44:20Z

+// entrypoint.basedir = baz
+// package.json.name = <from package.json>
+
+module.exports = function getProcessTags () {


Should the result of this function be cached here?

It's a property of SpanProcessor which is attached to the tracer singleton:

packages/dd-trace/src/opentracing/tracer.js 5:const SpanProcessor = require('../span_processor') 34: this._processor = new SpanProcessor(this._exporter, this._prioritySampler, config)

This reverts commit e272bb8.

tlhunter · 2025-12-09T19:42:42Z

I forgot that I had pushed a half-baked commit

- collects basic process tags - tag serializer - send in first chunk span every time we send traces to the agent - create DD_EXPERIMENTAL_PROPAGATE_PROCESS_TAGS_ENABLED=false to configure - TODO: as a follow-up this should only add tags to the first span of the first chunk of a network request

tlhunter force-pushed the tlhunter/process-tags branch from f80d984 to 48dcde7 Compare October 23, 2025 22:31

vandonr reviewed Oct 27, 2025

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Comment thread packages/dd-trace/src/proxy.js Outdated

tlhunter force-pushed the tlhunter/process-tags branch from 48dcde7 to 79d07ac Compare October 27, 2025 18:49

tlhunter force-pushed the tlhunter/process-tags branch 3 times, most recently from 337d9f1 to f067df3 Compare November 18, 2025 18:31

tlhunter added the semver-minor label Nov 19, 2025

tlhunter force-pushed the tlhunter/process-tags branch 4 times, most recently from df701f0 to 1035fc3 Compare November 19, 2025 21:26

tlhunter requested a review from pabloerhard November 19, 2025 21:45

tlhunter force-pushed the tlhunter/process-tags branch from 1035fc3 to 3e47727 Compare November 19, 2025 22:03

tlhunter marked this pull request as ready for review November 19, 2025 22:09

tlhunter requested review from a team as code owners November 19, 2025 22:09

tlhunter requested review from khanayan123 and removed request for a team November 19, 2025 22:09

dubloom reviewed Nov 21, 2025

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BridgeAR previously requested changes Nov 21, 2025

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Comment thread packages/dd-trace/src/config.js

tlhunter force-pushed the tlhunter/process-tags branch from 3e47727 to 3f40669 Compare November 24, 2025 22:32

tlhunter requested a review from BridgeAR November 24, 2025 22:48

tlhunter changed the title ~~collect and propagate process tags~~ collect and propagate process tags in first chunk span Dec 2, 2025

tlhunter mentioned this pull request Dec 3, 2025

[SVLS-7168] Create GCP PubSub Push Subscriptions Plugin #6260

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tlhunter marked this pull request as draft December 3, 2025 22:07

tlhunter force-pushed the tlhunter/process-tags branch from 3f40669 to 30589ac Compare December 3, 2025 22:08

tlhunter added 3 commits December 9, 2025 08:38

collect and propagate process tags

45e4fd8

fix env var, add tests

94d44de

attempt to only send in first span of network payload

e272bb8

tlhunter force-pushed the tlhunter/process-tags branch from 30589ac to e272bb8 Compare December 9, 2025 16:38

bengl requested changes Dec 9, 2025

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Revert "attempt to only send in first span of network payload"

be8242a

This reverts commit e272bb8.

tlhunter marked this pull request as ready for review December 9, 2025 19:42

rebuild

72ae510

bengl approved these changes Dec 10, 2025

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tlhunter merged commit 460bf14 into master Dec 10, 2025
885 of 887 checks passed

tlhunter deleted the tlhunter/process-tags branch December 10, 2025 19:20

dd-octo-sts Bot mentioned this pull request Dec 11, 2025

v5.81.0 proposal #6964

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