One metrics URL can reach several Traefik processes: a swarm service's
replicas behind the routing mesh or its VIP, a Kubernetes Service's pods,
a keepalived pair after failover, or the same Traefik after a restart.
Each keeps its own counters, so comparing one with another read the second
one's lifetime totals as new traffic: retired routers flashed 100% 502 and
an idle router showed 834 req/s whenever the scrape moved to the other
replica.
Each scrape is now keyed by Traefik's process_start_time_seconds and
compared only with the same process's previous scrape. A process seen for
the first time (or not in the last hour) sets its baseline and counts
nothing. Without a start time every scrape is one process, as before.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
