Arize Phoenix: JS exporter posts to the collector endpoint as given, dropping spans silently

Arize Phoenix: JS exporter posts to the collector endpoint as given, dropping spans silently

TL;DR

If your JS traces never show up in Phoenix but there are no errors, check what URL your exporter is actually posting to. Set the collector endpoint to the full traces path and hand it to the exporter untouched. Never let docs snippets bolt the path on by convention, since different SDKs disagree about which side does that.

Use this when you run into the situation in the title.

When not to use this skill: unrelated tasks. It covers only the procedure above.

Compatibility

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Details

Context: From GitHub issue arize-ai/phoenix#14875 (resolved by PR #14891). The Python SDKs treat PHOENIXCOLLECTORENDPOINT as a base URL and append the OTLP path themselves. The @mastra/arize ArizeExporter instead posts spans to exactly the endpoint it is handed, so with a bare base URL the spans went to the root instead of the traces path and were dropped. The batch exporter swallowed the delivery error, so the run looked clean while nothing landed in Phoenix. The fix the maintainers landed: make the collector variable the full traces URL and pass it straight through, while Phoenix's own tools strip the path when they need a base URL.

Source: From GitHub issue arize-ai/phoenix#14875 (resolved by PR #14891). The Python SDKs treat PHOENIXCOLLECTORENDPOINT as a base URL and append the OTLP path themselves. The @mastra/arize ArizeExporter instead posts spans to exactly the endpoint it is handed, so with a bare base URL the spans went to the root instead of the traces path and were dropped. The batch exporter swallowed the delivery error, so the run looked clean while nothing landed in Phoenix. The fix the maintainers landed: make the collector variable the full traces URL and pass it straight through, while Phoenix's own tools strip the path when they need a base URL.

Verified resolution: If your JS traces never show up in Phoenix but there are no errors, check what URL your exporter is actually posting to. Set the collector endpoint to the full traces path and hand it to the exporter untouched. Never let docs snippets bolt the path on by convention, since different SDKs disagree about which side does that.

Source URL: https://github.com/arize-ai/phoenix/issues/14875