[omnibus] Make system-probe binary builds use the GOMODCACHE env

[KSerrania]

What does this PR do?

Updates the system-probe binary build commands in the datadog-agent.rb software definition to pass the env hash.

This hash sets a number of environment variables (like GOPATH, LDFLAGS, CGO_CFLAGS, CGO_LDFLAGS, GOMODCACHE).

The GOMODCACHE one in particular is important, as it allows the command to reuse the go dependency cache that we prepare in the go_deps job. This helps avoid the total number of dependency downloads done from third-parties in the CI.

Since the system-probe binary build commands did not have this variable set, they were re-downloading their go dependencies. This sometimes caused download errors (example), making CI fail.

Motivation

Avoid unnecessary dependency downloads in CI.

Describe how to test/QA your changes

Full successful pipeline run.

Possible Drawbacks / Trade-offs

I could have passed only the GOMODCACHE variable to the commands to be extra safe. However, since all other go build commands in the software definition already pass the full env hash, I prefer having a uniform way of running all of them.

Additional Notes

n/a

[KSerrania]

/trigger-ci --variable RUN_ALL_BUILDS=true --variable RUN_KITCHEN_TESTS=true --variable RUN_E2E_TESTS=on --variable RUN_UNIT_TESTS=on --variable RUN_KMT_TESTS=on

[dd-devflow]

🚂 Gitlab pipeline started

Started pipeline #46052915

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Run ID: 57d45701-ecdc-44ff-bbcf-7e5a95367a39 Metrics dashboard Target profiles

Baseline: 2abc3be
Comparison: a88df33

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	trials	links
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+1.34	[+0.60, +2.08]	1	Logs
➖	basic_py_check	% cpu utilization	+1.20	[-1.50, +3.89]	1	Logs
➖	idle	memory utilization	+0.51	[+0.46, +0.56]	1	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	+0.36	[+0.30, +0.41]	1	Logs
➖	pycheck_lots_of_tags	% cpu utilization	+0.32	[-2.18, +2.82]	1	Logs
➖	otel_to_otel_logs	ingress throughput	+0.24	[-0.56, +1.05]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.01, +0.01]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	-0.02	[-0.12, +0.09]	1	Logs
➖	idle_all_features	memory utilization	-1.39	[-1.50, -1.29]	1	Logs
➖	file_tree	memory utilization	-1.49	[-1.62, -1.36]	1	Logs

Bounds Checks

perf	experiment	bounds_check_name	replicates_passed
✅	idle	memory_usage	10/10

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".

[spencergilbert]

🥜 nitpick: ‏ we seem to be using :env => env and env: env interchangeably here.

[alopezz]

🥜 nitpick: ‏ we seem to be using :env => env and env: env interchangeably here.

My 2c: I think env: env is the better syntax here and the one we should prefer; but without any sort of linter enforcing it we have no way to ensure consistency.

[KSerrania]

/merge

[dd-devflow]

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