[CONTP-403] Configure agent sidecar mutator to use config component

[gabedos]

What does this PR do?

Configures the agent sidecar mutator in the admission controller to use the Config Component instead of a global function call to the config.

Motivation

Tech-debt clean up. We want to use components to simplify dependencies.

Additional Notes

N/A

[agent-platform-auto-pr]

[Fast Unit Tests Report]

On pipeline 46112018 (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

[agent-platform-auto-pr]

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=46112018 --os-family=ubuntu

Note: This applies to commit aabad0a

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Run ID: 02e80ca4-e635-4eac-bb01-dcb56b805d18 Metrics dashboard Target profiles

Baseline: 1238b9b
Comparison: aabad0a

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
➖	pycheck_lots_of_tags	% cpu utilization	+0.98	[-1.50, +3.46]	1	Logs
➖	idle_all_features	memory utilization	+0.83	[+0.74, +0.92]	1	Logs
➖	idle	memory utilization	+0.62	[+0.58, +0.66]	1	Logs
➖	basic_py_check	% cpu utilization	+0.59	[-2.14, +3.31]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.01, +0.01]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	-0.00	[-0.10, +0.10]	1	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	-0.58	[-0.63, -0.53]	1	Logs
➖	otel_to_otel_logs	ingress throughput	-0.60	[-1.41, +0.21]	1	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-0.64	[-1.37, +0.10]	1	Logs
➖	file_tree	memory utilization	-1.32	[-1.44, -1.20]	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".

[gabedos]

/merge

[dd-devflow]

🚂 MergeQueue: pull request added to the queue

The median merge time in main is 27m.

Use /merge -c to cancel this operation!

[clamoriniere]

Hi @gabedos

Thanks for working on this improvement. The current state of this PR is a good start because it solves part of the technical depth: now, the global variable is not used in this webhook.

However the PR doesn't solve yet the performance issue generated by the fact that we call the config.GetString(...) function in the hot execution path which is costly in terms of CPU consumption (for some implementation reason the config Component is not caching the option value resolution).

I added some suggestions in the comments to solve the performance issue. Please let me know if my comments are clear enough.

[clamoriniere]

It is great to now have access to the config.Component in the newWebhook() function. However, instead of keeping a "pointer" to the config in the Webhook struct to get config option values later in other functions, all the values should be extracted in this function and be stored in this Webhook struct.

I will give more details in next comments

[clamoriniere]

the injectAgentSidecar() is part of the hot execution path: each time we receive a request we run this function. That is why we should not call the config.Component function in this function because retrieving config option value is costly.
For example we made this fix recently because we introduced a function that was using a config.Component function in a hot execution path. (see the fix: #29211)

So my suggestion is to make the getDefaultSidecarTemplate() function attached to the Webhook struct like injectAgentSidecar() and in the NewWebhook() call the the function datadogConfig.GetString("admission_controller.agent_sidecar.image_name") and store the value in Webhook struct.

and do it for any other option value that we get with datadogConfig.GetString(...).