Document mapping between gRPC (native) and OTel conventions #3229
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Pull request overview
This PR documents the mapping between gRPC native OpenTelemetry conventions (defined in gRPC proposals A66 for metrics and A72 for tracing) and the official OpenTelemetry semantic conventions for gRPC hosted in this repository. The documentation helps users understand how to convert between the two convention systems.
Key Changes
- Adds a new compatibility document (
docs/non-normative/compatibility/grpc-compatibility.md) providing detailed mappings for metrics, spans, and their attributes - Updates the gRPC conventions page to reference the new compatibility document
- Removes duplicate gRPC convention references from the RPC README
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 7 comments.
| File | Description |
|---|---|
docs/non-normative/compatibility/grpc-compatibility.md |
New compatibility document detailing attribute, metric, and span mappings between gRPC and OTel conventions, including conversion instructions |
docs/rpc/grpc.md |
Adds a note referencing the gRPC project's conventions and linking to the new compatibility document |
docs/rpc/README.md |
Removes redundant reference to gRPC specifications that is now better documented in the compatibility guide |
lmolkova
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This PR has been labeled as stale due to lack of activity. It will be automatically closed if there is no further activity over the next 7 days. |
lmolkova
commented
Jan 7, 2026
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| > [!NOTE] | ||
| > | ||
| > OpenTelemetry defines experimental [`rpc.client.request.size`](/docs/rpc/rpc-metrics.md#metric-rpcclientrequestsize) |
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Suggested change
| > OpenTelemetry defines experimental [`rpc.client.request.size`](/docs/rpc/rpc-metrics.md#metric-rpcclientrequestsize) | |
| > OpenTelemetry defines [`rpc.client.request.size`](/docs/rpc/rpc-metrics.md#metric-rpcclientrequestsize) |
lmolkova
commented
Jan 7, 2026
| > metrics measure uncompressed size and are recorded once per call even if the call involved | ||
| > multiple attempts. | ||
| > | ||
| > OpenTelemetry also defines experimental [`rpc.server.request.size`](/docs/rpc/rpc-metrics.md#metric-rpcserverrequestsize) |
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| > OpenTelemetry also defines experimental [`rpc.server.request.size`](/docs/rpc/rpc-metrics.md#metric-rpcserverrequestsize) | |
| > OpenTelemetry also defines [`rpc.server.request.size`](/docs/rpc/rpc-metrics.md#metric-rpcserverrequestsize) |
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| - `server.address` | ||
| - `server.port` |
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| | Property | gRPC | OpenTelemetry | Conversion comments | | ||
| | ---------- | ------------------------------------- | ------------------------------- | ------------------- | | ||
| | Event name | `Outbound message`, `Inbound message` | `rpc.message` | gRPC -> OTel: set to `rpc.message`<br>OTel -> gRPC: set to one of the message names depending on `rpc.message.type` | |
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todo: it's actually more complicated
gRPC records two events for one message sometimes - one with compressed size, another with uncompressed.
OTel records one event and includes size that are available.
lmolkova
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Jan 8, 2026
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| gRPC client call spans report an additional span event called `Delayed name resolution complete`. | ||
| When converting from gRPC to OTel spans, preserve this span event as-is. | ||
| When converting from OTel to gRPC spans, there is no way to represent this event. |
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Suggested change
| gRPC client call spans report an additional span event called `Delayed name resolution complete`. | |
| When converting from gRPC to OTel spans, preserve this span event as-is. | |
| When converting from OTel to gRPC spans, there is no way to represent this event. | |
| gRPC client call spans contain additional events that could be recorded as is when converting to OTel. |
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Fixes #1773
Document mapping between gRPC native metrics and spans and OTel gRPC metrics and spans.
TODO: