[Backport 7.64.x] [CWS] Forward signals from tracer to tracee

[agent-platform-auto-pr]

Backport 76af1ad from #34622.

---

What does this PR do?

This will fix the issue when a workload have some special handlers (like to cleanup gracefully when receiving a SIGTERM) and did not receive them if such signals were sent to the tracer by a container runtime.

Motivation

Describe how you validated your changes

• build this C program:

#include <stdio.h>
#include <signal.h>
#include <unistd.h>

void handle_sig(int sig) {
    printf("SIGNAL: %d\n", sig);
}

int main(int ac, char** av) {
    signal(SIGTERM, handle_sig);
    while (run) {
        puts("running");
        sleep(10);
    }
    return (0);
}

• then trace it: sudo cws-instrumentation trace --disable-proc-scan --probe-addr= -- ./a.out
• and send a SIGTERM to cws-instrumentation: $> sudo kill -TERM $(pidof cws-instrumentation)
• you should see printed: SIGNAL: 15

Possible Drawbacks / Trade-offs

Additional Notes

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• Anything else we should know when reviewing?
• Include benchmarking information here whenever possible.
• Include info about alternatives that were considered and why the proposed
  version was chosen.
  -->

[agent-platform-auto-pr]

[Fast Unit Tests Report]

On pipeline 57499383 (CI Visibility). The following jobs did not run any unit tests:

Jobs:

• tests_windows-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 aws.create-vm --pipeline-id=57499383 --os-family=ubuntu

Note: This applies to commit 2a97f47

[agent-platform-auto-pr]

Uncompressed package size comparison

Comparison with ancestor 6205bcf815e98e57d6d7d4125fe4f43f9812e12d

Diff per package

package	diff	status	size	ancestor	threshold
datadog-agent-x86_64-rpm	0.12MB	⚠️	878.91MB	878.79MB	0.50MB
datadog-agent-x86_64-suse	0.12MB	⚠️	878.91MB	878.79MB	0.50MB
datadog-agent-aarch64-rpm	0.11MB	⚠️	868.20MB	868.09MB	0.50MB
datadog-agent-amd64-deb	0.10MB	⚠️	869.12MB	869.02MB	0.50MB
datadog-agent-arm64-deb	0.09MB	⚠️	858.43MB	858.34MB	0.50MB
datadog-heroku-agent-amd64-deb	0.00MB	✅	446.34MB	446.34MB	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-aarch64-rpm	0.00MB	✅	59.33MB	59.33MB	0.50MB
datadog-dogstatsd-amd64-deb	0.00MB	✅	41.40MB	41.40MB	0.50MB
datadog-dogstatsd-arm64-deb	0.00MB	✅	39.66MB	39.66MB	0.50MB
datadog-iot-agent-amd64-deb	0.00MB	✅	62.02MB	62.02MB	0.50MB
datadog-iot-agent-arm64-deb	0.00MB	✅	59.26MB	59.26MB	0.50MB
datadog-dogstatsd-x86_64-rpm	-0.00MB	✅	41.48MB	41.48MB	0.50MB
datadog-dogstatsd-x86_64-suse	-0.00MB	✅	41.48MB	41.48MB	0.50MB

Decision

⚠️ Warning

[agent-platform-auto-pr]

Static quality checks ✅

Please find below the results from static quality gates

Successful checks

Info

Result	Quality gate	On disk size	On disk size limit	On wire size	On wire size limit
✅	static_quality_gate_agent_deb_amd64	840.66MiB	847.49MiB	203.01MiB	212.33MiB
✅	static_quality_gate_agent_deb_arm64	830.42MiB	836.66MiB	183.61MiB	192.5MiB
✅	static_quality_gate_agent_rpm_amd64	840.61MiB	847.82MiB	206.0MiB	215.76MiB
✅	static_quality_gate_agent_rpm_arm64	830.41MiB	836.66MiB	185.31MiB	194.24MiB
✅	static_quality_gate_agent_suse_amd64	840.76MiB	847.82MiB	206.0MiB	215.76MiB
✅	static_quality_gate_agent_suse_arm64	830.42MiB	836.66MiB	185.31MiB	194.24MiB
✅	static_quality_gate_dogstatsd_deb_amd64	39.56MiB	49.7MiB	10.55MiB	20.6MiB
✅	static_quality_gate_dogstatsd_deb_arm64	37.9MiB	48.1MiB	9.13MiB	19.1MiB
✅	static_quality_gate_dogstatsd_rpm_amd64	39.56MiB	49.7MiB	10.56MiB	20.6MiB
✅	static_quality_gate_dogstatsd_suse_amd64	39.56MiB	49.7MiB	10.56MiB	20.6MiB
✅	static_quality_gate_iot_agent_deb_amd64	59.22MiB	69.0MiB	14.88MiB	24.8MiB
✅	static_quality_gate_iot_agent_deb_arm64	56.59MiB	66.4MiB	12.84MiB	22.8MiB
✅	static_quality_gate_iot_agent_rpm_amd64	59.23MiB	69.0MiB	14.9MiB	24.8MiB
✅	static_quality_gate_iot_agent_rpm_arm64	56.59MiB	66.4MiB	12.85MiB	22.8MiB
✅	static_quality_gate_iot_agent_suse_amd64	59.22MiB	69.0MiB	14.9MiB	24.8MiB
✅	static_quality_gate_docker_agent_amd64	925.0MiB	931.7MiB	309.1MiB	318.67MiB
✅	static_quality_gate_docker_agent_arm64	938.07MiB	944.08MiB	294.09MiB	303.0MiB
✅	static_quality_gate_docker_agent_jmx_amd64	1.1GiB	1.1GiB	384.21MiB	393.75MiB
✅	static_quality_gate_docker_agent_jmx_arm64	1.1GiB	1.1GiB	365.17MiB	373.71MiB
✅	static_quality_gate_docker_dogstatsd_amd64	47.7MiB	57.88MiB	18.26MiB	28.29MiB
✅	static_quality_gate_docker_dogstatsd_arm64	46.09MiB	56.27MiB	17.02MiB	27.06MiB
✅	static_quality_gate_docker_cluster_agent_amd64	264.95MiB	274.78MiB	106.34MiB	116.28MiB
✅	static_quality_gate_docker_cluster_agent_arm64	280.93MiB	290.82MiB	101.17MiB	111.12MiB

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: b9ea4030-9e41-4fde-92d7-75347df56ca1

Baseline: a1e550e
Comparison: 2a97f47
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_idle_all_features	memory utilization	+0.20	[+0.15, +0.25]	1	Logs bounds checks dashboard
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+0.20	[-0.72, +1.11]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	+0.02	[-0.76, +0.81]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	+0.02	[-0.83, +0.87]	1	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	+0.02	[-0.05, +0.09]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.01	[-0.29, +0.31]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	+0.00	[-0.62, +0.63]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.03, +0.02]	1	Logs
➖	file_to_blackhole_300ms_latency	egress throughput	-0.01	[-0.64, +0.62]	1	Logs
➖	file_to_blackhole_0ms_latency_http1	egress throughput	-0.02	[-0.88, +0.84]	1	Logs
➖	file_to_blackhole_0ms_latency_http2	egress throughput	-0.02	[-0.82, +0.77]	1	Logs
➖	quality_gate_idle	memory utilization	-0.23	[-0.28, -0.18]	1	Logs bounds checks dashboard
➖	file_to_blackhole_1000ms_latency_linear_load	egress throughput	-0.35	[-0.82, +0.11]	1	Logs
➖	file_tree	memory utilization	-0.46	[-0.52, -0.41]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	-0.70	[-1.48, +0.08]	1	Logs
➖	quality_gate_logs	% cpu utilization	-1.09	[-4.02, +1.85]	1	Logs

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, 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 intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check lost_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_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.