refactor(emit): re-target agent OTLP export from gateway:4317 → backend:4317 - #243
Merged
Merged
Conversation
…nd:4317
The deployment is collapsing the data path from
agent → gateway → asapquery-backend
to
agent → asapquery-backend
because asapquery-backend's `--enable-otel-ingest` already accepts
sketch data points and merges them per-aggregation_id via its precompute
engine accumulators (DDSketchAccumulator / HLLAccumulator / etc.) — no
middle-tier OTel gateway merge processor is required.
Functional changes:
- `ThreeStageEmitter::emit_per_stage` (emitter.rs:379): default
`EdgeStageConfig.exporter_target` flips from `Stage(StageId::Gateway)`
to `Stage(StageId::Backend)`. Comment added explaining the rationale.
- All 4 edge-emit call sites of `build_otlp_exporter` /
`resolve_export_endpoint` flip `default_host` from `"gateway"` to
`"backend"`:
* `emit_edge_yaml` (stage_config.rs:231)
* `emit_edge_yaml_5sketch_routing` variant (stage_config.rs:966)
* OTAP edge emit, Modes 1 and 2 (otap.rs:191, 205)
* Telegraf edge emit, Modes 1 and 2 (telegraf.rs:90, 95)
- `emit_gateway_yaml` (stage_config.rs:461) unchanged — the gateway's
own OTLP exporter still targets `backend:4317` (correct).
Code kept-but-unused:
- `emit_gateway_yaml` + `StageConfig::Gateway` + `AgentRole::Gateway`
push remain in source. They no longer reach any subscriber in the
default deployment but are preserved per the "keep gateway impl in
source" intent. Topologies that re-introduce a middle tier can flip
EdgeStageConfig.exporter_target back to Stage(Gateway) post-emit.
Test updates:
- The 3 assertions that the agent YAML/TOML contains `gateway:4317` flip
to assert `backend:4317`:
* `stage_config.rs:1509-1513` (OTel agent yaml)
* `otap.rs:461-464` (OTAP agent yaml)
* `telegraf.rs:367-370, 399-402` (Telegraf agent toml)
- Doc-comment at `stage_config.rs:1196-1199` and the inline rationale
at `stage_config.rs:228` updated.
Build: clean. 686 lib tests + 27 binary tests pass.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Pre-flight for the upcoming ASAPCollector deployment PR that collapses the data path from
agent → gateway → asapquery-backendtoagent → asapquery-backend.Why this works: asapquery-backend's
--enable-otel-ingestalready accepts*SketchDataPoints and routes them through the precompute engine's accumulators (DDSketchAccumulator / HLLAccumulator / etc.) — these merge per-aggregation_id across all incoming agents server-side. No middle-tier OTel gateway merge processor is needed.Functional changes
ThreeStageEmitter::emit_per_stage— defaultEdgeStageConfig.exporter_targetflips fromStage(StageId::Gateway)→Stage(StageId::Backend).build_otlp_exporter/resolve_export_endpointflipdefault_hostfrom"gateway"→"backend":emit_edge_yaml(stage_config.rs:231)emit_edge_yaml_5sketch_routingvariant (stage_config.rs:966)emit_gateway_yamlunchanged — the gateway's own OTLP exporter still targetsbackend:4317(correct, when a deployment does run a gateway).Kept-in-source per ”keep gateway impl in repos” intent
emit_gateway_yaml,StageConfig::Gateway,AgentRole::Gatewaypush — all preserved. They no longer reach any subscriber in the default deployment, but topologies re-introducing a middle tier can flipEdgeStageConfig.exporter_targetback toStage(Gateway)post-emit.Test plan
cargo checkclean (only pre-existing warnings)cargo test --lib: 686 passed; 0 failedcargo test --tests --bins: 27 passed; 0 failedgateway:4317flip to assertbackend:4317.🤖 Generated with Claude Code