fix(collector): propagate shutdown context to worker hostname resolution

[louis-cqrl]

What does this PR do?

Propagate a proper shutdown context through Runner down to Worker.Run(),
replacing the context.TODO() used when calling hostname.Get().

The Runner now owns a context.Context (created in NewRunner) that is
cancelled at the start of Runner.Stop(). Each worker goroutine receives
this context and passes it to hostname.Get().

Motivation

hostname.Get() can trigger network I/O (e.g. an EC2 IMDS HTTP request)
on the first call before the result is cached. Using context.TODO()
meant there was no cancellation path: if the call blocked (misconfigured
IMDS endpoint, network partition), the worker goroutine could not be
interrupted during agent shutdown, potentially delaying or blocking the
shutdown sequence entirely.

Describe how you validated your changes

• CI

Additional Notes

This change only affects the first call to hostname.Get() per agent run;
subsequent calls return immediately from the cache and are unaffected by
context cancellation.

[agent-platform-auto-pr]

Static quality checks

✅ Please find below the results from static quality gates
Comparison made with ancestor 4623533
📊 Static Quality Gates Dashboard
🔗 SQG Job

Successful checks

Info

	Quality gate	Change	Size (prev → curr → max)
✅	docker_agent_amd64	-13.03 KiB (0.00% reduction)	817.041 → 817.029 → 821.990
✅	docker_agent_arm64	-13.03 KiB (0.00% reduction)	819.927 → 819.914 → 828.520
✅	docker_agent_jmx_amd64	-13.02 KiB (0.00% reduction)	1007.953 → 1007.940 → 1012.870
✅	docker_agent_jmx_arm64	-13.02 KiB (0.00% reduction)	999.621 → 999.608 → 1008.120
✅	docker_cluster_agent_amd64	-3.33 KiB (0.00% reduction)	203.002 → 202.999 → 204.270
✅	docker_cluster_agent_arm64	-3.31 KiB (0.00% reduction)	217.457 → 217.454 → 218.000

25 successful checks with minimal change (< 2 KiB)

	Quality gate	Current Size
✅	agent_deb_amd64	756.007 MiB
✅	agent_deb_amd64_fips	715.097 MiB
✅	agent_heroku_amd64	323.754 MiB
✅	agent_msi	622.075 MiB
✅	agent_rpm_amd64	755.991 MiB
✅	agent_rpm_amd64_fips	715.080 MiB
✅	agent_rpm_arm64	734.142 MiB
✅	agent_rpm_arm64_fips	696.217 MiB
✅	agent_suse_amd64	755.991 MiB
✅	agent_suse_amd64_fips	715.080 MiB
✅	agent_suse_arm64	734.142 MiB
✅	agent_suse_arm64_fips	696.217 MiB
✅	docker_cws_instrumentation_amd64	7.135 MiB
✅	docker_cws_instrumentation_arm64	6.689 MiB
✅	docker_dogstatsd_amd64	38.500 MiB
✅	docker_dogstatsd_arm64	36.812 MiB
✅	dogstatsd_deb_amd64	29.720 MiB
✅	dogstatsd_deb_arm64	27.881 MiB
✅	dogstatsd_rpm_amd64	29.720 MiB
✅	dogstatsd_suse_amd64	29.720 MiB
✅	iot_agent_deb_amd64	42.617 MiB
✅	iot_agent_deb_arm64	39.723 MiB
✅	iot_agent_deb_armhf	40.447 MiB
✅	iot_agent_rpm_amd64	42.618 MiB
✅	iot_agent_suse_amd64	42.618 MiB

On-wire sizes (compressed)

	Quality gate	Change	Size (prev → curr → max)
✅	agent_deb_amd64	+19.89 KiB (0.01% increase)	185.464 → 185.483 → 186.090
✅	agent_deb_amd64_fips	-44.93 KiB (0.02% reduction)	176.270 → 176.226 → 180.330
✅	agent_heroku_amd64	-4.75 KiB (0.01% reduction)	87.103 → 87.098 → 88.440
✅	agent_msi	neutral	149.199 MiB → 154.470
✅	agent_rpm_amd64	neutral	187.339 MiB → 189.170
✅	agent_rpm_amd64_fips	-31.51 KiB (0.02% reduction)	178.429 → 178.398 → 181.060
✅	agent_rpm_arm64	-28.86 KiB (0.02% reduction)	169.790 → 169.762 → 170.020
✅	agent_rpm_arm64_fips	-30.36 KiB (0.02% reduction)	162.498 → 162.469 → 164.130
✅	agent_suse_amd64	neutral	187.339 MiB → 189.170
✅	agent_suse_amd64_fips	-31.51 KiB (0.02% reduction)	178.429 → 178.398 → 181.060
✅	agent_suse_arm64	-28.86 KiB (0.02% reduction)	169.790 → 169.762 → 170.020
✅	agent_suse_arm64_fips	-30.36 KiB (0.02% reduction)	162.498 → 162.469 → 164.130
✅	docker_agent_amd64	neutral	277.780 MiB → 279.410
✅	docker_agent_arm64	+21.43 KiB (0.01% increase)	265.034 → 265.055 → 267.960
✅	docker_agent_jmx_amd64	neutral	346.425 MiB → 348.040
✅	docker_agent_jmx_arm64	neutral	329.681 MiB → 332.560
✅	docker_cluster_agent_amd64	+12.13 KiB (0.02% increase)	71.121 → 71.133 → 71.920
✅	docker_cluster_agent_arm64	+8.5 KiB (0.01% increase)	66.767 → 66.775 → 67.220
✅	docker_cws_instrumentation_amd64	neutral	2.995 MiB → 3.330
✅	docker_cws_instrumentation_arm64	neutral	2.726 MiB → 3.090
✅	docker_dogstatsd_amd64	neutral	14.900 MiB → 15.820
✅	docker_dogstatsd_arm64	neutral	14.239 MiB → 14.830
✅	dogstatsd_deb_amd64	neutral	7.855 MiB → 8.790
✅	dogstatsd_deb_arm64	neutral	6.741 MiB → 7.710
✅	dogstatsd_rpm_amd64	neutral	7.865 MiB → 8.800
✅	dogstatsd_suse_amd64	neutral	7.865 MiB → 8.800
✅	iot_agent_deb_amd64	neutral	11.236 MiB → 12.040
✅	iot_agent_deb_arm64	neutral	9.601 MiB → 10.450
✅	iot_agent_deb_armhf	neutral	9.805 MiB → 10.620
✅	iot_agent_rpm_amd64	neutral	11.256 MiB → 12.060
✅	iot_agent_suse_amd64	neutral	11.256 MiB → 12.060

[cit-pr-commenter-54b7da]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 294685a3-ea50-49c5-93ff-d49f8c6731b5

Baseline: 4623533
Comparison: ba8a159
Diff

Optimization Goals: ✅ No significant changes detected

Experiments ignored for regressions

Regressions in experiments with settings containing erratic: true are ignored.

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	docker_containers_cpu	% cpu utilization	+2.84	[-0.34, +6.01]	1	Logs

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	docker_containers_cpu	% cpu utilization	+2.84	[-0.34, +6.01]	1	Logs
➖	quality_gate_metrics_logs	memory utilization	+1.16	[+0.95, +1.36]	1	Logs bounds checks dashboard
➖	otlp_ingest_logs	memory utilization	+0.95	[+0.85, +1.04]	1	Logs
➖	quality_gate_logs	% cpu utilization	+0.75	[-0.77, +2.28]	1	Logs bounds checks dashboard
➖	tcp_syslog_to_blackhole	ingress throughput	+0.70	[+0.61, +0.79]	1	Logs
➖	ddot_metrics_sum_cumulativetodelta_exporter	memory utilization	+0.33	[+0.10, +0.56]	1	Logs
➖	docker_containers_memory	memory utilization	+0.27	[+0.19, +0.34]	1	Logs
➖	ddot_metrics_sum_delta	memory utilization	+0.24	[+0.06, +0.43]	1	Logs
➖	ddot_metrics_sum_cumulative	memory utilization	+0.18	[+0.02, +0.35]	1	Logs
➖	ddot_logs	memory utilization	+0.11	[+0.04, +0.17]	1	Logs
➖	quality_gate_idle	memory utilization	+0.09	[+0.04, +0.13]	1	Logs bounds checks dashboard
➖	file_to_blackhole_1000ms_latency	egress throughput	+0.03	[-0.40, +0.46]	1	Logs
➖	uds_dogstatsd_to_api_v3	ingress throughput	+0.01	[-0.11, +0.13]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.01	[-0.08, +0.11]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.01	[-0.12, +0.14]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	-0.00	[-0.38, +0.38]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	-0.02	[-0.51, +0.46]	1	Logs
➖	ddot_metrics	memory utilization	-0.05	[-0.26, +0.16]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	-0.06	[-0.10, -0.02]	1	Logs bounds checks dashboard
➖	file_to_blackhole_100ms_latency	egress throughput	-0.08	[-0.12, -0.03]	1	Logs
➖	uds_dogstatsd_20mb_12k_contexts_20_senders	memory utilization	-0.08	[-0.13, -0.02]	1	Logs
➖	otlp_ingest_metrics	memory utilization	-0.09	[-0.24, +0.07]	1	Logs
➖	file_tree	memory utilization	-0.19	[-0.23, -0.14]	1	Logs

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	links
✅	docker_containers_cpu	simple_check_run	10/10
✅	docker_containers_memory	memory_usage	10/10
✅	docker_containers_memory	simple_check_run	10/10
✅	file_to_blackhole_0ms_latency	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency	lost_bytes	10/10
✅	file_to_blackhole_1000ms_latency	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_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	bounds checks dashboard
✅	quality_gate_logs	lost_bytes	10/10	bounds checks dashboard
✅	quality_gate_logs	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	cpu_usage	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	lost_bytes	10/10	bounds checks dashboard
✅	quality_gate_metrics_logs	memory_usage	10/10	bounds checks dashboard

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_metrics_logs, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check lost_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check memory_usage: 10/10 replicas passed. Gate 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 intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check memory_usage: 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.