[HOLD][npcollector] Fix statsd client

[AlexandreYang]

Superseded by #25708

What does this PR do?

[npcollector] Fix statsd client

statsd.Client is assigned/configured at runtime, currently we might get the NoOpClient instead of the actual statsdClient. This PR fixes that issue by wrapping inside a function.

datadog-agent/pkg/process/statsd/statsd.go

Lines 13 to 22 in 939b135

	// Client is a global Statsd client. When a client is configured via Configure,
	// that becomes the new global Statsd client in the package.
	var Client statsd.ClientInterface = &statsd.NoOpClient{}
	// Configure creates a statsd client from a dogweb.ini style config file and set it to the global Statsd.
	func Configure(host string, port int, create func(string, int, ...statsd.Option) (statsd.ClientInterface, error)) error {
	var err error
	Client, err = create(host, port)
	return err
	}

Motivation

Additional Notes

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

[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=34535645 --os-family=ubuntu

[pr-commenter]

Regression Detector

Regression Detector Results

Run ID: 3ff701ad-2245-4bbc-8c22-fe698c8b38a2
Baseline: 0e8fe47
Comparison: ebd2611

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
➖	basic_py_check	% cpu utilization	+2.00	[-0.55, +4.55]
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+0.97	[-1.90, +3.84]
➖	idle	memory utilization	+0.34	[+0.30, +0.39]
➖	file_tree	memory utilization	+0.08	[-0.04, +0.20]
➖	otel_to_otel_logs	ingress throughput	+0.04	[-0.32, +0.39]
➖	uds_dogstatsd_to_api	ingress throughput	+0.01	[-0.19, +0.21]
➖	trace_agent_json	ingress throughput	+0.00	[-0.01, +0.01]
➖	trace_agent_msgpack	ingress throughput	-0.00	[-0.00, +0.00]
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.03	[-0.07, +0.01]
➖	tcp_syslog_to_blackhole	ingress throughput	-0.71	[-21.80, +20.38]
➖	pycheck_1000_100byte_tags	% cpu utilization	-2.91	[-7.59, +1.78]

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".

[hmahmood]

I am not sure what problem this PR is solving. When are you seeing that you get the no-op client?

[AlexandreYang]

@hmahmood (starting a thread since it's easier to follow discussions)

I am not sure what problem this PR is solving. When are you seeing that you get the no-op client?

When I log the statsd.Client it displays this:

2024-05-17 08:24:04 PDT | PROCESS | INFO | (comp/networkpath/npcollector/npcollectorimpl/npcollector.go:79 in newNpCollectorImpl) | statsd.Client &statsd.NoOpClient{}

I think it's because the NpCollector component is created before statsd Configure() is called:

datadog-agent/pkg/process/statsd/statsd.go

Lines 18 to 22 in 939b135

	func Configure(host string, port int, create func(string, int, ...statsd.Option) (statsd.ClientInterface, error)) error {
	var err error
	Client, err = create(host, port)
	return err
	}

Also, I'm not seeing any statsd metrics being reported due to use of NoOpClient.

[leeavital]

I haven't worked much with fx -- should we be injecting the statsd client? In general DI frameworks are supposed to solve these configuration ordering issues.

[AlexandreYang]

Hi @leeavital , I think you are right, statsd client should be injected as component instead of using a global (currently).

I will reach processes team to see if that's something we can do.

[AlexandreYang]

Superseded by #25708