Through one address Steward read whichever replica answered, and with
host-mode ports behind a keepalived VIP that can be the replica serving
nothing: since the 18:43 restart every scrape landed on Docker03's idle
Traefik, which has no traefik_service_* series, so no router was stored.
A metrics_url host name that resolves to several addresses (a swarm
service's tasks.<service>, a Kubernetes headless Service, round-robin DNS)
is now scraped address by address, with the original Host header and TLS
name. Answers from one process are kept once; a replica that doesn't answer
is skipped with a warning. Requests, bytes and latency buckets are summed
over the replicas that have a baseline, so the sum's rise is the sum of each
one's own rise; certificates are listed once; Traefik's own figures add
connections and memory and keep the newest reload. A name with one address
is one scrape, as before.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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>