oss_10_otlp_partial_success

[ocelotl]

Closes #10

Fixes OTLP partial-success handling (Linear OSS-10, finding X1): both transports (gRPC + HTTP) and all three signals (traces, metrics, logs) now deserialize the export response and log a warning with the rejected count / error_message on partial success. A partial success is still a SUCCESS return; it is no longer silent data loss.

Linear issue: https://linear.app/dash0/issue/OSS-10/x1-otlp-partial-success-responses-ignored-all-signals-both-transports

[ocelotl]

🔒 Internal (dash0) — not for upstream.

• Linear: https://linear.app/dash0/issue/OSS-10/x1-otlp-partial-success-responses-ignored-all-signals-both-transports (finding X1)
• Closes: oss_10_otlp_partial_success #10 · Branch/worktree: oss_10_otlp_partial_success · Commit: 9a2699c7d
• Validation: gRPC suite 69 passed, HTTP suite 65 passed; scope contained to the two OTLP exporter packages + changelog.

[ocelotl]

📣 Public-facing draft — to be opened upstream in open-telemetry/opentelemetry-python. No internal references; copy verbatim.

Title: Handle OTLP partial_success responses (log rejected telemetry)

What

Deserialize the OTLP export response on both transports (gRPC and HTTP/protobuf) for all three signals (traces, metrics, logs), and log a warning when the collector reports a partial success (a non-zero rejected_* count or a non-empty error_message). A shared _log_partial_success helper is added per transport.

Why

Previously the exporters returned SUCCESS without ever inspecting the response body, so collector-rejected spans / data points / log records were dropped silently — data loss with no diagnostic. The OTLP exporter spec requires surfacing partial success.

Details

• gRPC: bind the previously-discarded Export(...) return value and pass it to the helper.
• HTTP: deserialize resp.content at each signal's export call site, before returning SUCCESS on resp.ok.
• A partial success is still SUCCESS (the request was accepted); the change only logs. An unparseable body is swallowed so it cannot turn a successful export into a failure.

Testing

New unit tests per transport/signal: (a) a partial-success response with a rejected count logs a warning containing the count; (b) a fully-successful response logs nothing. Existing suites pass (gRPC 69, HTTP 65).