appsec: implement waf.error and rasp.error

[cataphract]

Description

See APPSEC-62689

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 169947b8fc

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[pr-commenter]

Benchmarks [ tracer ]

Benchmark execution time: 2026-06-08 20:33:06

Comparing candidate commit 5cbd457 in PR branch glopes/waf-rasp-error-metric with baseline commit 8b837e8 in branch master.

Found 1 performance improvements and 3 performance regressions! Performance is the same for 190 metrics, 0 unstable metrics.

Explanation

This is an A/B test comparing a candidate commit's performance against that of a baseline commit. Performance changes are noted in the tables below as:

• 🟩 = significantly better candidate vs. baseline
• 🟥 = significantly worse candidate vs. baseline

We compute a confidence interval (CI) over the relative difference of means between metrics from the candidate and baseline commits, considering the baseline as the reference.

If the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD), the change is considered significant.

Feel free to reach out to #apm-benchmarking-platform on Slack if you have any questions.

More details about the CI and significant changes

You can imagine this CI as a range of values that is likely to contain the true difference of means between the candidate and baseline commits.

CIs of the difference of means are often centered around 0%, because often changes are not that big:

---------------------------------(------|---^--------)-------------------------------->
                              -0.6%    0%  0.3%     +1.2%
                                 |          |        |
         lower bound of the CI --'          |        |
sample mean (center of the CI) -------------'        |
         upper bound of the CI ----------------------'

As described above, a change is considered significant if the CI is entirely outside the configured SIGNIFICANT_IMPACT_THRESHOLD (or the deprecated UNCONFIDENCE_THRESHOLD).

For instance, for an execution time metric, this confidence interval indicates a significantly worse performance:

----------------------------------------|---------|---(---------^---------)---------->
                                       0%        1%  1.3%      2.2%      3.1%
                                                  |   |         |         |
       significant impact threshold --------------'   |         |         |
                      lower bound of CI --------------'         |         |
       sample mean (center of the CI) --------------------------'         |
                      upper bound of CI ----------------------------------'

scenario:SamplingRuleMatchingBench/benchRegexMatching1

• 🟥 execution_time [+51.262ns; +107.338ns] or [+3.487%; +7.301%]

scenario:SamplingRuleMatchingBench/benchRegexMatching2

• 🟥 execution_time [+37.994ns; +116.006ns] or [+2.566%; +7.833%]

scenario:SamplingRuleMatchingBench/benchRegexMatching3

• 🟥 execution_time [+37.071ns; +116.729ns] or [+2.509%; +7.899%]

scenario:TraceSerializationBench/benchSerializeTrace

• 🟩 execution_time [-26.601µs; -10.699µs] or [-5.109%; -2.055%]

[estringana]

is there no test checking for this new tags?

[cataphract]

These tags are only issued if there is a bug. libddwaf doesn't return failures otherwise. Initially, I added new environment variables to simulate a failure and tested those, but environment variables and filtered on libdatadog, so it became too complicated.