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[OTel] Undecided: what should the shared AnyValue decoder do with unlisted container attributes? #208
Description
Problem or motivation
Split out of the #187 review, as agreed there. This is a design question rather than a feature — filing under this template because blank issues are disabled; relabel as needed.
It is downstream of #169 rather than a duplicate: #169 asks whether the internal model should be the OTLP model at all, this asks what the current flattening does with a container value in the meantime. If #169 lands as described, this question disappears with it — which is itself an argument for not over-engineering the answer here.
"What happens to an arbitrary container attribute" has never actually been decided. Before #187 the two paths disagreed, and both behaviours were accidents rather than choices:
# extraction.py, pre-#187 — containers dropped entirely
if "stringValue" ... elif "intValue" ... elif "doubleValue" ... elif "boolValue" ...
return result
# loader/otlp.py, pre-#187 — containers JSON-dumped as raw proto
elif "arrayValue" in value_obj:
result[key] = json.dumps(value_obj["arrayValue"])#187 picks the first one for every unlisted key, purely so the PR changes no behaviour, and defers the real decision here.
Proposed solution
Pick one deliberately. The options as I see them:
| Behaviour | Cost | |
|---|---|---|
| Drop (today, post-#187) | Value disappears, warning logged | Silent data loss for legitimate array attributes like process.command_args |
| JSON-dump the decoded value | ["stop"] rather than {"values":[{"stringValue":"stop"}]} |
Consumers that expected absence now get a string; changes truthiness in if attrs.get(k): branches |
| Keep the container | Full fidelity | Any consumer using the value as a dict key or set member raises TypeError, on an unauthenticated receiver port |
Whatever is chosen, SPEC_CONTAINER_ATTRS stays as the set that gets native containers; this is only about the default for everything else.
Happy to implement whichever direction you pick.
Alternatives considered
Leaving it as-is (drop) indefinitely. That is defensible while #169 is open, but it is currently an accident inherited from extraction.py rather than a 1decision, and nothing in the code says so.
Additional context
resource_attrs flows into session.metadata and then to the UI, so this is user-visible rather than purely internal. Standard resource semconv has array-typed attributes we hold no constants for — process.command_args is one. Under "drop" they stay invisible; under "JSON-dump" they would start appearing in session metadata.
Human confirmation
- I am a human (not a bot, agent, or AI) filing this issue.
Activity
fix(otel): decode containers on an opt-in allowlist instead of a deny…
fix(otel): share one AnyValue decoder across all OTLP paths (#187)