Validate Enum arguments before registering the collector#1189
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csmarchbanks merged 1 commit intoJul 15, 2026
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Enum.__init__ called super().__init__() -- which registers the collector
in the CollectorRegistry -- before validating that states is non-empty
and that the metric name does not overlap a label name. When either
check failed, the ValueError was raised as expected, but a half-built
Enum (whose _states was never assigned) had already been registered.
That left the registry in a broken state: the name was permanently
taken, so recreating the metric raised 'Duplicated timeseries', and any
subsequent scrape crashed with
AttributeError: 'Enum' object has no attribute '_states'
when _child_samples iterated self._states. A realistic trigger is
building the states list from configuration that turns out to be empty.
Gauge and Histogram already validate before calling super().__init__();
this moves Enum's two guards ahead of registration to match, so a failed
constructor leaves the registry untouched.
Add test_failed_init_does_not_pollute_registry, which asserts that after
two failed Enum constructions the name is still free, the metric can be
created, and the registry scrapes cleanly.
Signed-off-by: Sean Kim <[email protected]>
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Enum.init called super().init() -- which registers the collector
in the CollectorRegistry -- before validating that states is non-empty
and that the metric name does not overlap a label name. When either
check failed, the ValueError was raised as expected, but a half-built
Enum (whose _states was never assigned) had already been registered.
That left the registry in a broken state: the name was permanently
taken, so recreating the metric raised 'Duplicated timeseries', and any
subsequent scrape crashed with
when _child_samples iterated self._states. A realistic trigger is
building the states list from configuration that turns out to be empty.
Gauge and Histogram already validate before calling super().init();
this moves Enum's two guards ahead of registration to match, so a failed
constructor leaves the registry untouched.
Add test_failed_init_does_not_pollute_registry, which asserts that after
two failed Enum constructions the name is still free, the metric can be
created, and the registry scrapes cleanly.
@csmarchbanks