[APMSP-1280] pkg/trace: refactor peer tags config and add to info endpoint

[knusbaum]

What does this PR do?

This PR refactors the configuration of 'peer tags' to make it more consistent across the various pieces of code that use them, and exposes them through the agent's info endpoint.

Motivation

Clients will need peer tags in order to calculate trace stats. We want to make sure the same set of peer tags are used everywhere.

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

Write an e2e test that configures peer tagging and ensures we get the expected tags in stats.

[cit-pr-commenter]

Go Package Import Differences

Baseline: ae49421
Comparison: 047b943

binary	os	arch	change
agent	windows	amd64	+1, -0 +gopkg.in/ini.v1

[ichinaski]

Looks good overall, maybe remove the code that is commented out?

[knusbaum]

@ichinaski

Looks good overall, maybe remove the code that is commented out?

Yes, for sure. There's some cleanup to do, and the commented tests are there for now so I can go back and create their equivalents in the config code so we cover those cases where that logic now lives.

[pr-commenter]

Regression Detector

Regression Detector Results

Run ID: 091982f6-df4e-4e46-9d30-49121b848cdf Metrics dashboard Target profiles

Baseline: ae49421
Comparison: 047b943

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

No significant changes in experiment optimization goals

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

There were no significant changes in experiment optimization goals at this confidence level and effect size tolerance.

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	links
➖	tcp_syslog_to_blackhole	ingress throughput	+0.80	[-12.06, +13.65]	Logs
➖	otel_to_otel_logs	ingress throughput	+0.61	[-0.20, +1.43]	Logs
➖	file_tree	memory utilization	+0.14	[+0.08, +0.21]	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.01, +0.01]	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.00	[-0.00, +0.00]	Logs
➖	idle	memory utilization	-0.10	[-0.13, -0.06]	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.14	[-1.01, +0.74]	Logs
➖	pycheck_1000_100byte_tags	% cpu utilization	-0.18	[-4.88, +4.52]	Logs
➖	basic_py_check	% cpu utilization	-0.48	[-3.07, +2.11]	Logs

Explanation

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

[ichinaski]

LGTM

[pr-commenter]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv create-vm --pipeline-id=40684404 --os-family=ubuntu

Note: This applies to commit 047b943

[knusbaum]

/merge

[dd-devflow]

🚂 MergeQueue: pull request added to the queue

The median merge time in main is 23m.

Use /merge -c to cancel this operation!