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Switch firmware to the protobuf-free exporters and drop protobuf and Abseil #114
Description
Parent
Part of #102
What to build
Firmware that emits traces, metrics and logs through the protobuf-free OTLP/JSON exporters over the cJSON writer backend, and links neither protobuf nor Abseil.
Target: this repository, on the integration branch.
All three signals must switch together: leaving any one on the protobuf path keeps the runtime linked and yields no binary saving. Profiles already need no protobuf and stay as they are.
With the dependency gone, the workarounds this component carries solely to keep protobuf and Abseil compiling and linking for an embedded target should be removed.
Acceptance criteria
- Traces, metrics and logs export through the protobuf-free path over the cJSON backend
- The firmware links neither protobuf nor Abseil
- Workarounds that existed only for protobuf or Abseil are deleted
- Kconfig lets the protobuf-based exporters be selected instead, for comparison
- The component builds with exceptions and RTTI disabled, as before
- Binary inspection confirms protobuf and Abseil are absent
Blocked by
- Complete the issue #38 CMake gating so protobuf can be excluded #108
- cJSON JsonWriter backend, proven by porting the profiles exporter #109
- Protobuf-free OTLP/JSON metric exporter #111
- Protobuf-free OTLP/JSON log record exporter #112
- JsonReader and protobuf-free partial-success response parsing #113
Activity
ltowarek commentedon Sep 11, 2026
Implemented in
9ab0551e4faa7206621b188a19defcc728f3f49d("Export traces, metrics and logs over OTLP/JSON without protobuf", branchotlp-json-no-protobuf, "Closes #114"). Traces, metrics and logs export through the protobuf-free path over the cJSON backend, the firmware links neither protobuf nor Abseil (image 2.39 MB → 1.42 MB on examples/otlp), and the Kconfig choice keeps the protobuf exporters selectable for comparison.One caveat on the third acceptance criterion: the protobuf/Abseil-only workarounds are gated on
ESP_OPENTELEMETRY_NEEDS_PROTOBUFrather than deleted, because the protobuf encoding and the JTAG exporters still need them. Finishing that as an actual deletion is tracked separately in #118, which this commit split out.Export traces, metrics and logs over OTLP/JSON without protobuf