fix(logger): accept resolvable IANA timezone aliases in timestamps - #5458
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…k timestamps consistent
Replace the Intl.supportedValuesOf('timeZone') membership check with
resolution-based validation via Intl.DateTimeFormat construction. The
canonical-only list rejected valid aliases such as Asia/Kolkata, causing
timestamps to mix UTC clock digits with the local offset and denote the
wrong instant. Resolution-based validation also stays correct when future
ICU versions flip the canonical list to IANA primary names.
When the timezone cannot be resolved (e.g. TZ=:/etc/localtime), fall back
to UTC for both the date digits and the offset suffix, and emit a one-time
warning instead of failing silently.
Fixes #5456
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svozza
approved these changes
Jul 13, 2026
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Summary
The Logger validated the
TZtimezone againstIntl.supportedValuesOf('timeZone'), which contains canonical identifiers only. Valid IANA aliases likeAsia/Kolkata(the IANA primary name for India) were silently rejected, producing timestamps with UTC clock digits but a local offset suffix — i.e. the wrong instant. This PR switches to resolution-based validation, delegating alias knowledge entirely toIntl.DateTimeFormat, and makes the UTC fallback internally consistent and no longer silent.Changes
Intl.supportedValuesOf('timeZone')membership check inLogFormatterwith a try/catch aroundIntl.DateTimeFormatconstruction, so any timezone ICU can resolve (canonical or alias) is accepted; this also stays correct when future ICU versions flip the canonical list to IANA primary names (ECMA-402 change)+00:00when falling back to UTC, so an unresolvableTZ(e.g.:/etc/localtime, preserving the fix for Bug: logger breaks on nodejs Docker lambdas since 2.4.0 #2851) can no longer produce a timestamp mixing UTC digits with a non-zero local offsetAsia/Kolkataalias, offset consistency on fallback, and the one-time warningIssue number: closes #5456
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