enhancement(datadog encoder): support for metrics v3 protocol

[tobz]

Summary

Change Type

• Bug fix
• New feature
• Non-functional (chore, refactoring, docs)
• Performance

How did you test this PR?

References

[tobz]

• enhancement(datadog encoder): support for metrics v3 protocol #1175 👈 (View in Graphite)
• main

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[pr-commenter]

Binary Size Analysis (Agent Data Plane)

Target: bdcdc6c (baseline) vs 16afa2e (comparison) diff
Analysis Type: Stripped binaries (debug symbols excluded)
Baseline Size: 26.47 MiB
Comparison Size: 26.62 MiB
Size Change: +152.62 KiB (+0.56%)
Pass/Fail Threshold: +5%
Result: PASSED ✅

Changes by Module

Module	File Size	Symbols
saluki_components::encoders::datadog	+73.02 KiB	325
core	+38.09 KiB	9191
anyhow	+9.05 KiB	1302
hashbrown	+7.45 KiB	363
saluki_common::task::instrument	+7.44 KiB	70
[sections]	+5.52 KiB	9
[Unmapped]	-4.81 KiB	1
protobuf	+4.74 KiB	12
saluki_components::common::datadog	-4.39 KiB	319
http	+3.85 KiB	317
agent_data_plane::cli::run	+3.11 KiB	82
saluki_io::compression::Compressor<W>	+2.49 KiB	3
saluki_io::net::util	+2.24 KiB	130
serde_core	+2.09 KiB	351
uuid	+1.85 KiB	4
agent_data_plane::components::apm_onboarding	-1.36 KiB	34
saluki_components::transforms::dogstatsd_mapper	-976 B	18
saluki_components::forwarders::datadog	+824 B	22
saluki_components::forwarders::otlp	-650 B	60
serde_json	+546 B	175

Detailed Symbol Changes

    FILE SIZE        VM SIZE    
 --------------  -------------- 
  [NEW] +1.79Mi  [NEW] +1.79Mi    std::thread::local::LocalKey<T>::with::hc4ab4ecb1e791a86
  +1.1%  +147Ki  +1.2%  +131Ki    [22490 Others]
  [NEW]  +122Ki  [NEW]  +122Ki    agent_data_plane::cli::run::create_topology::_{{closure}}::h87eff169ee6c6a27
  [NEW] +67.3Ki  [NEW] +67.2Ki    saluki_components::common::datadog::io::run_endpoint_io_loop::_{{closure}}::hc4516879514a2a08
  [NEW] +62.1Ki  [NEW] +62.0Ki    agent_data_plane::cli::run::handle_run_command::_{{closure}}::ha5dcf4212e573f38
  [NEW] +58.7Ki  [NEW] +58.4Ki    _<agent_data_plane::internal::control_plane::PrivilegedApiWorker as saluki_core::runtime::supervisor::Supervisable>::initialize::_{{closure}}::h30f35d64f65ba63d
  [NEW] +49.6Ki  [NEW] +49.4Ki    saluki_app::bootstrap::AppBootstrapper::bootstrap::_{{closure}}::h5053651f0bda4aaa
  [NEW] +47.4Ki  [NEW] +47.3Ki    moka::sync::base_cache::Inner<K,V,S>::do_run_pending_tasks::h43bb4bf0b6f2bc50
  [NEW] +46.4Ki  [NEW] +46.3Ki    h2::proto::connection::Connection<T,P,B>::poll::h14f55357aa1a69bb
  [NEW] +46.3Ki  [NEW] +46.1Ki    _<saluki_components::destinations::prometheus::Prometheus as saluki_core::components::destinations::Destination>::run::_{{closure}}::hba93477fbb085aa3
  [NEW] +45.6Ki  [NEW] +45.4Ki    _<saluki_components::forwarders::otlp::OtlpForwarder as saluki_core::components::forwarders::Forwarder>::run::_{{closure}}::hfe9d1c75781916ba
  [DEL] -46.2Ki  [DEL] -46.0Ki    _<saluki_components::forwarders::otlp::OtlpForwarder as saluki_core::components::forwarders::Forwarder>::run::_{{closure}}::h9e6a07604104748f
  [DEL] -46.2Ki  [DEL] -46.0Ki    _<saluki_components::destinations::prometheus::Prometheus as saluki_core::components::destinations::Destination>::run::_{{closure}}::h804b0075faebe88b
  [DEL] -46.4Ki  [DEL] -46.3Ki    h2::proto::connection::Connection<T,P,B>::poll::hded4fb5f8a002638
  [DEL] -47.5Ki  [DEL] -47.3Ki    moka::sync::base_cache::Inner<K,V,S>::do_run_pending_tasks::heca9fca4e5bc0d83
  [DEL] -49.6Ki  [DEL] -49.4Ki    saluki_app::bootstrap::AppBootstrapper::bootstrap::_{{closure}}::hd83d25f4c7e8a1ae
  [DEL] -58.7Ki  [DEL] -58.4Ki    _<agent_data_plane::internal::control_plane::PrivilegedApiWorker as saluki_core::runtime::supervisor::Supervisable>::initialize::_{{closure}}::hf1e132bb3e8bfeaf
  [DEL] -62.0Ki  [DEL] -61.9Ki    agent_data_plane::cli::run::handle_run_command::_{{closure}}::hbff4cb15be99fca3
  [DEL] -64.2Ki  [DEL] -64.1Ki    saluki_components::common::datadog::io::run_endpoint_io_loop::_{{closure}}::h7847418cb5d4cb46
  [DEL]  -119Ki  [DEL]  -119Ki    agent_data_plane::cli::run::create_topology::_{{closure}}::h5c132aa500e2a433
  [DEL] -1.79Mi  [DEL] -1.79Mi    std::thread::local::LocalKey<T>::with::hddbf5b47575f6048
  +0.6%  +152Ki  +0.6%  +137Ki    TOTAL

[pr-commenter]

Regression Detector (Agent Data Plane)

Regression Detector Results

Run ID: f239cfbd-066c-4ca0-8dd3-4a7ebe106213

Baseline: bdcdc6c
Comparison: 16afa2e
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
➖	otlp_ingest_logs_5mb_cpu	% cpu utilization	+1.40	[-3.55, +6.34]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_logs_5mb_throughput	ingress throughput	+0.02	[-0.11, +0.14]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_logs_5mb_memory	memory utilization	-4.20	[-4.38, -4.01]	1	(metrics) (profiles) (logs)

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	dsd_uds_500mb_3k_contexts_throughput	ingress throughput	+2.22	[+2.08, +2.35]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_ottl_filtering_5mb_cpu	% cpu utilization	+1.83	[-0.71, +4.38]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_logs_5mb_cpu	% cpu utilization	+1.40	[-3.55, +6.34]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_5mb_cpu	% cpu utilization	+0.84	[-1.39, +3.07]	1	(metrics) (profiles) (logs)
➖	quality_gates_rss_dsd_medium	memory utilization	+0.74	[+0.55, +0.93]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_ottl_transform_5mb_memory	memory utilization	+0.46	[+0.21, +0.70]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_5mb_memory	memory utilization	+0.41	[+0.16, +0.67]	1	(metrics) (profiles) (logs)
➖	dsd_uds_100mb_3k_contexts_memory	memory utilization	+0.37	[+0.19, +0.54]	1	(metrics) (profiles) (logs)
➖	dsd_uds_10mb_3k_contexts_memory	memory utilization	+0.27	[+0.08, +0.45]	1	(metrics) (profiles) (logs)
➖	quality_gates_rss_dsd_ultraheavy	memory utilization	+0.25	[+0.13, +0.38]	1	(metrics) (profiles) (logs)
➖	quality_gates_rss_idle	memory utilization	+0.12	[+0.08, +0.15]	1	(metrics) (profiles) (logs)
➖	dsd_uds_500mb_3k_contexts_memory	memory utilization	+0.11	[-0.06, +0.27]	1	(metrics) (profiles) (logs)
➖	dsd_uds_512kb_3k_contexts_memory	memory utilization	+0.03	[-0.14, +0.20]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_metrics_5mb_throughput	ingress throughput	+0.03	[-0.09, +0.14]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_logs_5mb_throughput	ingress throughput	+0.02	[-0.11, +0.14]	1	(metrics) (profiles) (logs)
➖	dsd_uds_512kb_3k_contexts_throughput	ingress throughput	+0.01	[-0.05, +0.06]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_ottl_transform_5mb_throughput	ingress throughput	+0.00	[-0.02, +0.02]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_5mb_throughput	ingress throughput	+0.00	[-0.02, +0.02]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_ottl_filtering_5mb_throughput	ingress throughput	+0.00	[-0.02, +0.02]	1	(metrics) (profiles) (logs)
➖	dsd_uds_1mb_3k_contexts_throughput	ingress throughput	-0.00	[-0.06, +0.06]	1	(metrics) (profiles) (logs)
➖	dsd_uds_10mb_3k_contexts_throughput	ingress throughput	-0.00	[-0.14, +0.13]	1	(metrics) (profiles) (logs)
➖	dsd_uds_100mb_3k_contexts_throughput	ingress throughput	-0.01	[-0.04, +0.02]	1	(metrics) (profiles) (logs)
➖	dsd_uds_1mb_3k_contexts_memory	memory utilization	-0.06	[-0.23, +0.11]	1	(metrics) (profiles) (logs)
➖	quality_gates_rss_dsd_low	memory utilization	-0.10	[-0.29, +0.09]	1	(metrics) (profiles) (logs)
➖	dsd_uds_500mb_3k_contexts_cpu	% cpu utilization	-0.15	[-1.60, +1.30]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_ottl_filtering_5mb_memory	memory utilization	-0.28	[-0.61, +0.05]	1	(metrics) (profiles) (logs)
➖	quality_gates_rss_dsd_heavy	memory utilization	-0.41	[-0.55, -0.28]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_metrics_5mb_memory	memory utilization	-1.57	[-1.79, -1.35]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_metrics_5mb_cpu	% cpu utilization	-2.41	[-9.62, +4.79]	1	(metrics) (profiles) (logs)
➖	dsd_uds_100mb_3k_contexts_cpu	% cpu utilization	-2.81	[-8.98, +3.37]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_traces_ottl_transform_5mb_cpu	% cpu utilization	-2.91	[-4.92, -0.91]	1	(metrics) (profiles) (logs)
➖	dsd_uds_512kb_3k_contexts_cpu	% cpu utilization	-3.42	[-59.97, +53.13]	1	(metrics) (profiles) (logs)
➖	otlp_ingest_logs_5mb_memory	memory utilization	-4.20	[-4.38, -4.01]	1	(metrics) (profiles) (logs)
➖	dsd_uds_10mb_3k_contexts_cpu	% cpu utilization	-4.36	[-35.06, +26.33]	1	(metrics) (profiles) (logs)
➖	dsd_uds_1mb_3k_contexts_cpu	% cpu utilization	-5.54	[-58.31, +47.24]	1	(metrics) (profiles) (logs)

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	observed_value	links
✅	quality_gates_rss_dsd_heavy	memory_usage	10/10	114.78MiB ≤ 140MiB	(metrics) (profiles) (logs)
✅	quality_gates_rss_dsd_low	memory_usage	10/10	34.25MiB ≤ 50MiB	(metrics) (profiles) (logs)
✅	quality_gates_rss_dsd_medium	memory_usage	10/10	54.66MiB ≤ 75MiB	(metrics) (profiles) (logs)
✅	quality_gates_rss_dsd_ultraheavy	memory_usage	10/10	169.28MiB ≤ 200MiB	(metrics) (profiles) (logs)
✅	quality_gates_rss_idle	memory_usage	10/10	21.48MiB ≤ 40MiB	(metrics) (profiles) (logs)

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".

[tobz]

This is temporarily blocked on there being a version of the Datadog Agent for us to test against in correctness tests that has up-to-date v3 metrics support.

Currently, we're hitting an issue related to rate intervals being delta encoded when they shouldn't be. That bug is fixed in DataDog/datadog-agent#45825 but won't be released until 7.77: roughly 2 weeks from now before an RC is available to use. We can potentially do a hacky image build or something for keep going in the meantime and then switch back to a proper Agent version once available, we'll see.

[tobz]

We've temporarily handled the issue of correctness tests by using a "dev" container image (datadoghq/agent-dev) based on the latest fix for V3 support in the Datadog Agent. With this in place, we're now currently passing for both dsd-plain (V2 payloads) and dsd-plain-v3 (new, V3 payloads only).

We can't merge this as-is: we need to wait for at least an RC build of Datadog Agent 7.77 so we can pin to a non-development image. In the meantime, I'm going to work on making sure we've integrated all of the same small fixes/changes that have been steadily being made upstream in the Datadog Agent repository for V3 support.

[vickenty]

This doesn't seem to observe any intake payload size limits, or am I missing anything?

[tobz]

That's correct.

Right now, we're either flushing with the V2 encoder determines it needs to flush (so that we generate an equivalent payload in terms of the contained metrics between the two) or if we exceed the configured maximum metrics per payload limit.

In V2/V3 mode, I suppose it's entirely possible to have the V3 payload exceed the payload limits, although it would be incredibly unlikely. In V3 only mode, it's obviously a much more likely risk.

My thought process was that we would improve this -- make V3 encoding aware of the payload limits -- at the same time we added incremental compression to match the behavior of the Agent... since back when this was originally written many weeks ago, it seemed like we'd have enough time between then and "V3 only in production / for customers" to do the follow-up work.

I guess the question I have is: do you feel like we still have that sort of time before we want to be running V3 only?

[vickenty]

Is it intentional that batch_seq and batch_len are hard-coded as 0 and 1?

[tobz]

It is intentional, but only in the context of us not currently splitting V3 payloads: there can literally only ever be a single V3 payload in each batch.

(Mostly related to the question you left about not obeying intake payload size limits.)