A general alert rule with Duration:0 (accepted by the API, no minimum
validation) drove fail*100/total with total==0, panicking with an integer
divide-by-zero inside checkStatus, which has no recover and would take down the
whole alert goroutine — a config-reachable DoS by any user able to create alert
rules. Skip duration<=0 rules in Check via continue (not boundCheck, which would
pollute hasPassedRule and skip sibling valid rules). Also trim the sample slice
when max<=0 in alertsentinel, otherwise it appended every tick without ever
trimming. Adds regression tests for zero-only and mixed rule sets.
naiba
0759f5c801