fix(ssi): disabled webhooks should not mutate

[betterengineering]

What does this PR do?

This commit resolves a bug where even when the tags from labels and config webhook were disabled, the auto instrumentation webhook would still mutate them.

Motivation

As part of Kubernetes SSI | Workload Selection 🎯](https://docs.google.com/document/d/1Lol1ExLF1nGBe7njO6DBVkjuYAYxC1-sL2WP0rdqFRk/edit?usp=sharing), we split the webhook logic and ensured that the autoinstrumentation webhook would apply all mutators it needed.

There are two config variables used for enabling the webhook:

• admission_controller.auto_instrumentation.enabled low level to control enabling/disabling the webhook
• apm_config.instrumentation.enabled the customer exposed config for enabling/disabling mutation

Because we chain together the mutators, our mutator does not apply because apm_config.instrumentation.enabled is set to false and our mutator checks filter.IsNamespaceEnabled. But the other mutators do apply because of they check filter.ShouldMutatePod.

Describe how you validated your changes

The additional unit tests should cover this scenario.

Possible Drawbacks / Trade-offs

We could also change what it means to have the autoinstrumentation webhook enabled and have it tied directly to apm_config.instrumentation.enabled. That broke tests and made me nervous.

Additional Notes

I feel good about the test added. I feel less confident in the fix and I'd love feedback on it

[stanistan]

Should this just be "null" since we're casting the results to strings in the assertion?

[stanistan]

I think one of your testcases should be a billing service. given target/label matches.

[betterengineering]

This one actually broke the test. Good call

[agent-platform-auto-pr]

Uncompressed package size comparison

Comparison with ancestor 4eb26be6e00997517dc6a6393199396ad23dcf7e

Diff per package

package	diff	status	size	ancestor	threshold
datadog-agent-amd64-deb	0.00MB	✅	817.87MB	817.87MB	0.50MB
datadog-agent-x86_64-rpm	0.00MB	✅	827.66MB	827.66MB	0.50MB
datadog-agent-x86_64-suse	0.00MB	✅	827.66MB	827.66MB	0.50MB
datadog-agent-arm64-deb	0.00MB	✅	808.84MB	808.84MB	0.50MB
datadog-agent-aarch64-rpm	0.00MB	✅	818.62MB	818.62MB	0.50MB
datadog-dogstatsd-amd64-deb	0.00MB	✅	39.42MB	39.42MB	0.50MB
datadog-dogstatsd-x86_64-rpm	0.00MB	✅	39.50MB	39.50MB	0.50MB
datadog-dogstatsd-x86_64-suse	0.00MB	✅	39.50MB	39.50MB	0.50MB
datadog-dogstatsd-arm64-deb	0.00MB	✅	37.96MB	37.96MB	0.50MB
datadog-heroku-agent-amd64-deb	0.00MB	✅	443.28MB	443.28MB	0.50MB
datadog-iot-agent-amd64-deb	0.00MB	✅	62.02MB	62.02MB	0.50MB
datadog-iot-agent-x86_64-rpm	0.00MB	✅	62.09MB	62.09MB	0.50MB
datadog-iot-agent-x86_64-suse	0.00MB	✅	62.09MB	62.09MB	0.50MB
datadog-iot-agent-arm64-deb	0.00MB	✅	59.27MB	59.27MB	0.50MB
datadog-iot-agent-aarch64-rpm	0.00MB	✅	59.33MB	59.33MB	0.50MB

Decision

✅ Passed

[agent-platform-auto-pr]

[Fast Unit Tests Report]

On pipeline 56961558 (CI Visibility). The following jobs did not run any unit tests:

Jobs:

• tests_flavor_dogstatsd_deb-x64
• tests_flavor_heroku_deb-x64
• tests_flavor_iot_deb-x64

If you modified Go files and expected unit tests to run in these jobs, please double check the job logs. If you think tests should have been executed reach out to #agent-devx-help

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 1b61f5a6-9d8b-4898-af03-8e9fb41d1dd5

Baseline: 4eb26be
Comparison: 78cfa3e
Diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	quality_gate_logs	% cpu utilization	+0.23	[-2.70, +3.16]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	+0.15	[+0.10, +0.20]	1	Logs bounds checks dashboard
➖	file_to_blackhole_0ms_latency	egress throughput	+0.03	[-0.84, +0.89]	1	Logs
➖	file_to_blackhole_0ms_latency_http2	egress throughput	+0.02	[-0.81, +0.86]	1	Logs
➖	file_to_blackhole_0ms_latency_http1	egress throughput	+0.02	[-0.78, +0.81]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.01	[-0.28, +0.30]	1	Logs
➖	file_to_blackhole_300ms_latency	egress throughput	+0.01	[-0.62, +0.63]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.01	[-0.04, +0.03]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	-0.01	[-0.68, +0.67]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	-0.02	[-0.80, +0.77]	1	Logs
➖	file_to_blackhole_1000ms_latency_linear_load	egress throughput	-0.04	[-0.50, +0.43]	1	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	-0.31	[-0.37, -0.26]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	-0.37	[-1.16, +0.42]	1	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.39	[-1.26, +0.49]	1	Logs
➖	file_tree	memory utilization	-0.55	[-0.62, -0.49]	1	Logs
➖	quality_gate_idle	memory utilization	-1.27	[-1.31, -1.23]	1	Logs bounds checks dashboard

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	links
✅	file_to_blackhole_0ms_latency	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency	memory_usage	10/10
✅	file_to_blackhole_0ms_latency_http1	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency_http1	memory_usage	10/10
✅	file_to_blackhole_0ms_latency_http2	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency_http2	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency_linear_load	memory_usage	10/10
✅	file_to_blackhole_100ms_latency	lost_bytes	10/10
✅	file_to_blackhole_100ms_latency	memory_usage	10/10
✅	file_to_blackhole_300ms_latency	lost_bytes	10/10
✅	file_to_blackhole_300ms_latency	memory_usage	10/10
✅	file_to_blackhole_500ms_latency	lost_bytes	10/10
✅	file_to_blackhole_500ms_latency	memory_usage	10/10
✅	quality_gate_idle	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10
✅	quality_gate_logs	lost_bytes	10/10
✅	quality_gate_logs	memory_usage	10/10

Explanation

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

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

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".

CI Pass/Fail Decision

✅ Passed. All Quality Gates passed.

• quality_gate_idle_all_features, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check lost_bytes: 10/10 replicas passed. Gate passed.