ersalil opened a new pull request, #68284:
URL: https://github.com/apache/airflow/pull/68284
## Summary
`SafeOtelLogger.gauge()` and `timer()` were missing the
`name_is_otel_safe()` guard that `incr()`, `decr()`, and `timing()` all have. A
DAG filename containing a space (e.g. `PBI_SKU_Performance copy.py`) caused the
DagProcessor to crash on every loop iteration when OTel metrics were enabled.
## Why
The DagProcessor emits a gauge metric for every known DAG file on every
parsing loop:
```python
Stats.gauge(f"dag_processing.last_run.seconds_ago.{file_name}", seconds_ago)
```
`gauge()` only validated against the allow/block list
(`metrics_validator.test()`), which does not check OTel naming rules. A
filename with a space passed that check and reached `meter.create_gauge()`
inside the OTel SDK, which raised a plain Exception that propagated uncaught
and crashed the process:
```
Exception: Expected ASCII string of maximum length 63 characters but got
airflow.dag_processing.last_run.seconds_ago.PBI_SKU_Performance copy
```
Note: the OTel SDK error message says "63 characters" but this is a stale
message — the actual SDK validation regex allows up to 255 characters (matching
OTEL_NAME_MAX_LENGTH). The real rejection reason is the space character, which
is not a valid OTel instrument name character. See
[open-telemetry/opentelemetry-python#3442](https://github.com/open-telemetry/opentelemetry-python/pull/3442).
The same gap existed in `timer()`: it had no validation at all before being
passed to `_OtelTimer`, which would then call `record_histogram_value()` with
the invalid name at `.stop()` time.
## Fix
Added `metrics_validator.test(stat) and name_is_otel_safe(self.prefix,
stat)` to `gauge()` (both the `stat` and `back_compat_name` paths) and
`timer()`, making all five recording methods consistent:
| Method | Guard before | Guard after |
|--------|-------------|-------------|
| `incr()` | ✅ both checks | ✅ unchanged |
| `decr()` | ✅ both checks | ✅ unchanged |
| `timing()` | ✅ both checks | ✅ unchanged |
| `gauge()` | ❌ validator only | ✅ both checks |
| `timer()` | ❌ none | ✅ both checks |
## Testing
- `test_gauge_with_invalid_stat_names_skipped_without_raising` — covers the
exact reported scenario (space in filename) and non-ASCII, both reproducing the
DagProcessor crash path.
- `test_timer_with_invalid_stat_name_does_not_record` — covers non-ASCII and
space for the timer path.
closes: #68282
##### Was generative AI tooling used to co-author this PR?
- [X] Yes — Claude Code (Sonnet 4.6)
This PR was prepared with Gen-AI assistance (Claude). I reviewed all
generated code.
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