feat(sampling): accept Remote Config list-shape tags natively#2033
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bm1549 wants to merge 1 commit into
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feat(sampling): accept Remote Config list-shape tags natively#2033bm1549 wants to merge 1 commit into
bm1549 wants to merge 1 commit into
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SamplingRuleConfig::tags now accepts both the map shape
({"env": "prod"}) and the Remote Config wire shape
([{"key": "env", "value_glob": "prod"}]). List entries missing
"key" or "value_glob" produce a deserialization error — we don't
silently drop entries because doing so could broaden a tag-
constrained rule.
This removes the per-tracer normalize_rc_tags workaround. The
dd-trace-rs caller stops normalizing in a follow-up PR once
this lands in a libdatadog release.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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Codecov Report❌ Patch coverage is Additional details and impacted files@@ Coverage Diff @@
## main #2033 +/- ##
==========================================
+ Coverage 72.80% 72.87% +0.07%
==========================================
Files 458 458
Lines 75789 75856 +67
==========================================
+ Hits 55177 55280 +103
+ Misses 20612 20576 -36
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iunanua
approved these changes
May 25, 2026
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What does this PR do?
Makes
libdd_sampling::SamplingRuleConfig::tagsaccept two wire shapes:{"env": "prod"}(current).[{"key": "env", "value_glob": "prod"}](new).Internally both normalize to
HashMap<String, String>. List entries missingkeyorvalue_globproduce a deserialization error. We don't silently drop bad entries because doing so could broaden a tag-constrained sampling rule.Motivation
Remote Config delivers
tracing_sampling_rulesentries with tags in the list shape. The previous#[serde(default)]ontagsonly accepted the map shape, so every tracer adoptinglibdd-samplinghas to normalize at the tracer ↔ libdatadog boundary. dd-trace-rs ships anormalize_rc_tagshelper for this. With this change, that workaround is no longer needed in any tracer.Additional Notes
tagsfield type staysHashMap<String, String>; only the deserializer is broader.serde::Deserializer::deserialize_any, which is safe for self-describing formats (JSON). Non-self-describing formats (bincode/postcard) would fail at deserialization time with a clear serde error.normalize_rc_tagsworkaround once this lands in a libdatadog release.How to test the change?
Four unit tests in
libdd-sampling/src/sampling_rule_config.rs:test_sampling_rule_config_tags_accepts_map_shape(regression).test_sampling_rule_config_tags_accepts_rc_list_shape.test_sampling_rule_config_tags_list_with_malformed_entry_rejects.test_sampling_rule_config_tags_absent_defaults_to_empty.Run:
cargo test -p libdd-sampling sampling_rule_config_tags.Integration verified locally against DataDog/dd-trace-rs#227: pointing dd-trace-rs at this branch and removing its
normalize_rc_tagsworkaround keeps all 352 dd-trace-rs tests green, including the handler-level tag tests that now traverse the upstream deserializer end-to-end.