feat(datadog-ffe): server-side EVP flagevaluation payload + bincode-safe sidecar delivery#2117
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leoromanovsky wants to merge 12 commits into
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feat(datadog-ffe): server-side EVP flagevaluation payload + bincode-safe sidecar delivery#2117leoromanovsky wants to merge 12 commits into
leoromanovsky wants to merge 12 commits into
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…ure gate - Add telemetry/flagevaluation.rs with FfeFlagEvaluationBatch and FfeFlagEvaluationEvent types modeled on exposures.rs - Required fields: timestamp, flag.key, first_evaluation, last_evaluation, evaluation_count - Optional fields use skip_serializing_if = Option::is_none for omitempty semantics (reviewer concern #2 review:4477935835) - Context pruning helper prune_context() enforces 256 fields / 256 chars skip-not-truncate (reviewer concern #1 review:4477935835) - New Cargo feature flagevaluation-evp gates the module (parallel to exposure-events) - Gate telemetry module in lib.rs to include flagevaluation-evp feature - 30 tests pass (25 existing + 5 new); OTel evaluation_metrics.rs and exposures.rs are byte-for-byte unchanged
…P flusher - Add ffe_flagevaluation_flusher.rs: structural copy of ffe_exposures_flusher.rs with path constant EVP_FLAGEVALUATIONS_PATH = /evp_proxy/v2/api/v2/flagevaluations and batch type FfeFlagEvaluationBatch; fire-and-forget send_batch with non-2xx warn+drop and timeout via biased tokio::select! - Add SidecarAction::FfeFlagEvaluationBatch variant to mod.rs enum; re-export FfeFlagEvaluationBatch from datadog-ffe telemetry module - Route SidecarAction::FfeFlagEvaluationBatch in sidecar_server.rs to ffe_flagevaluation_flusher::send_batch (parallel to FfeExposureBatch arm) - Add exhaust arm for new variant in telemetry.rs process_actions match - Enable flagevaluation-evp feature on datadog-ffe dep in sidecar Cargo.toml - 40 sidecar tests pass (3 new: posts_to_evp_proxy, non_2xx_does_not_panic, timeout_returns_without_waiting); OTel FfeEvaluationMetric path untouched
The worker->sidecar IPC serializes SidecarAction with bincode (non-self-describing). serde_json::Value (deserialize_any) and #[serde(skip_serializing_if)] both make bincode deserialize fail, so the sidecar silently dropped every FfeFlagEvaluationBatch ('IPC serve: failed to decode request') while the worker enqueue still returned ok.
- Carry pruned context as a JSON-object string (Option<String>); remove all skip_serializing_if from the wire types (keep #[serde(default)] for deserialize).
- Re-expand the context string into a JSON object and strip null/false/empty placeholders in ffe_flagevaluation_flusher::build_payload (POST shape unchanged; degraded tier carries no null placeholders).
- Add enqueue_actions_reliable (checked blocking send + reconnect-retry) for one-shot FFE batches; best-effort enqueue_actions left unchanged for high-volume telemetry.
- Add a bincode round-trip test for FfeFlagEvaluationBatch (mixed Some/None fields) to lock the wire-codec contract.
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📚 Documentation Check Results📦
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🔒 Cargo Deny Results📦
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Artifact Size Benchmark Reportaarch64-alpine-linux-musl
aarch64-unknown-linux-gnu
libdatadog-x64-windows
libdatadog-x86-windows
x86_64-alpine-linux-musl
x86_64-unknown-linux-gnu
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…46-ffe-flagevaluation-evp
…46-ffe-flagevaluation-evp
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Motivation
PHP delivers server-side EVP
flagevaluationbatches through libdatadog and the sidecar. That path needs to preserve bincode IPC compatibility, coalesce PHP request-lifetime batches without hidden dimensions, and emit worker-schema-compatible EVP JSON without adding OpenFeaturereasonto payloads or aggregate keys.Changes
FfeFlagEvaluationBatchafter existing variants.context.evaluationover IPC as a JSON-object string and re-expands it to an object for outbound EVP JSON.false,"",{}, and[]in user context.reasonargument.targeting_rule.key.Decisions
reasonis not part of the native ABI, sidecar event, outbound EVP payload, or aggregation contract.Validation Evidence
Current pushed libdatadog PR head:
3350d4b55c0815143e656f334967e4e4b6dd11f5.git diff --check- PASS.cargo fmt --check- PASS; rustfmt printed existing stable-toolchain warnings for unstable config keys.cargo check -p datadog-sidecar- PASS.cargo +stable clippy -p datadog-sidecar --all-targets --all-features -- -D warnings- PASS.cargo nextest run -p datadog-sidecar ffe_flagevaluation_flusher- PASS, 14 passed, 35 skipped.cargo test -p datadog-ffe --features flagevaluation-evp- PASS, 32 unit tests passed and 10 doc tests passed.cargo test -p datadog-ffe --features flagevaluation-evp telemetry::flagevaluation- PASS, 7 passed.cargo test -p datadog-sidecar ffe_flagevaluation_flusher- PASS, 14 passed.Companion PHP validation using this libdatadog head:
RUSTC_BOOTSTRAP=1 cargo test -p datadog-php ffe -- --nocapturefromdd-trace-php- PASS, 23 passed../tooling/bin/build-debug-artifact gnu-aarch64-8.0-nts /Users/leo.romanovsky/gsd-workspaces/flag-evaluations-cross-sdk/system-tests-clean-php/binariesfromdd-trace-php- PASS; produceddd-library-php-1.21.0-aarch64-linux-gnu.tar.gz.SYSTEM_TEST_BUILD_TIMEOUT=1800 ./build.sh --library php --weblog-variant apache-mod-8.0fromsystem-tests-clean-php- PASS on 2026-06-20.TEST_LIBRARY=php WEBLOG_VARIANT=apache-mod-8.0 ./run.sh +l php FEATURE_FLAGGING_AND_EXPERIMENTATION -k "test_flag_eval_evp"- PASS on 2026-06-20,8 passed, 2627 deselected in 60.08swithLibrary: php@1.21.0.payloads=30,events=10195, totalevaluation_count=12708;evp-degradation-flagemitted10001rows with totalevaluation_count=12000, including one degraded row withevaluation_count=2000and omittedtargeting_key/context.CI refresh on 2026-06-20:
allchecksis red after timing out while polling completed checks.