Add apm_config.obfuscation.cache.max_size to set the maximum size of obfuscation query cache

[keisku]

What does this PR do?

Add DD_APM_OBFUSCATION_CACHE_MAX_SIZE (= apm_config.obfuscation.cache.max_size) to set the maximum size of obfuscation cache.

Motivation

The cache size was fixed to 5000000 (= 5000 bytes * 1000 queries) because the maximum length of resource length is 5000 and 1000 queries were expected to be enough for caching. However, DBM was not considered when determining this value.

#31336 enabled obfuscation cache by default for the DBM context other than APM. I think 5000000 bytes is not ideal value for all DBM customers. Therefore, I'd rather make the cache size be configurable.

Describe how you validated your changes

We can see this debug log with the following Dockerfile and docker-compose.yaml.

docker run --name datadog-agent -d --cgroupns host --pid host \
-v /var/run/docker.sock:/var/run/docker.sock:ro \
-v /proc/:/host/proc/:ro -v /sys/fs/cgroup/:/host/sys/fs/cgroup:ro \
-e DD_API_KEY=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx \
-e DD_APM_OBFUSCATION_CACHE_MAX_SIZE=654321 \
datadog/agent-dev:keisku-obfuscation-cache-size-py3

docker exec -it datadog-agent agent config
.....
    cache:
      enabled: true
      max_size: 654321

Possible Drawbacks / Trade-offs

The default size is unchanged.

Additional Notes

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 7c09f827-3acf-454b-9c38-d359f2e01d50

Baseline: f8da8a4
Comparison: 523a21d
Diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	file_tree	memory utilization	+0.52	[+0.39, +0.65]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	+0.33	[-0.45, +1.10]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	+0.05	[-0.73, +0.83]	1	Logs
➖	file_to_blackhole_1000ms_latency_linear_load	egress throughput	+0.01	[-0.46, +0.49]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.01	[-0.09, +0.12]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	+0.00	[-0.85, +0.86]	1	Logs
➖	file_to_blackhole_300ms_latency	egress throughput	+0.00	[-0.64, +0.65]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.01, +0.01]	1	Logs
➖	file_to_blackhole_0ms_latency_http2	egress throughput	-0.01	[-0.85, +0.83]	1	Logs
➖	file_to_blackhole_0ms_latency_http1	egress throughput	-0.07	[-0.92, +0.78]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	-0.12	[-0.20, -0.03]	1	Logs bounds checks dashboard
➖	file_to_blackhole_1000ms_latency	egress throughput	-0.24	[-1.02, +0.55]	1	Logs
➖	quality_gate_logs	% cpu utilization	-0.32	[-3.53, +2.90]	1	Logs
➖	quality_gate_idle	memory utilization	-0.44	[-0.48, -0.40]	1	Logs bounds checks dashboard
➖	tcp_syslog_to_blackhole	ingress throughput	-1.02	[-1.08, -0.97]	1	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	-1.24	[-1.91, -0.57]	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	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	bounds checks dashboard
✅	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_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, bounds check memory_usage: 10/10 replicas passed. Gate passed.

[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=51783904 --os-family=ubuntu

Note: This applies to commit 523a21d

[agent-platform-auto-pr]

Uncompressed package size comparison

Comparison with ancestor f8da8a498f2836e70da3423d91a0a1519b446c29

Diff per package

package	diff	status	size	ancestor	threshold
datadog-agent-x86_64-rpm	0.11MB	⚠️	1200.09MB	1199.97MB	140.00MB
datadog-agent-x86_64-suse	0.11MB	⚠️	1200.09MB	1199.97MB	140.00MB
datadog-agent-aarch64-rpm	0.11MB	⚠️	944.36MB	944.24MB	140.00MB
datadog-agent-amd64-deb	0.09MB	⚠️	1190.80MB	1190.71MB	140.00MB
datadog-agent-arm64-deb	0.09MB	⚠️	935.09MB	935.00MB	140.00MB
datadog-heroku-agent-amd64-deb	0.09MB	⚠️	505.20MB	505.11MB	70.00MB
datadog-dogstatsd-arm64-deb	0.00MB	✅	55.77MB	55.77MB	10.00MB
datadog-iot-agent-arm64-deb	0.00MB	✅	108.81MB	108.81MB	10.00MB
datadog-dogstatsd-x86_64-rpm	-0.00MB	✅	78.65MB	78.65MB	10.00MB
datadog-dogstatsd-x86_64-suse	-0.00MB	✅	78.65MB	78.65MB	10.00MB
datadog-iot-agent-aarch64-rpm	-0.00MB	✅	108.88MB	108.88MB	10.00MB
datadog-iot-agent-x86_64-rpm	-0.00MB	✅	113.41MB	113.41MB	10.00MB
datadog-iot-agent-x86_64-suse	-0.00MB	✅	113.41MB	113.41MB	10.00MB
datadog-dogstatsd-amd64-deb	-0.00MB	✅	78.57MB	78.57MB	10.00MB
datadog-iot-agent-amd64-deb	-0.00MB	✅	113.34MB	113.34MB	10.00MB

Decision

⚠️ Warning

[louis-cqrl]

LGTM overall

[louis-cqrl]

why this value is not equal to 5000000 ?

[keisku]

Looks env var is prioritized. I added a test case that expects o.Cache.MaxSize equals to 5555555 to TestFullYamlConfig.