The "Database size" stat had no thresholds, so Grafana applied its stat
default (green base, red at >=80). The query is pg_database_size_bytes, so a
healthy ~9 MiB database (9.4M >> 80) rendered permanently RED on the
Scrabble - Resources dashboard (test + prod), reading as a false alert; the
neighbouring percentunit cache-hit stat stayed green only because its 0..1
values fall under 80.
Add absolute byte thresholds sized to the 40 GiB prod disk (4.6 GiB used,
observability bounded -- Tempo <=1 GiB, Prometheus 7d -- so the DB is the
only unbounded grower): green up to 8 GiB, yellow at 8 GiB (~20% of disk),
red at 16 GiB (~40%), an early warning with ample runway before the disk
tightens, not a panic line. Cosmetic panel coloring only; there are no
Grafana alert rules provisioned.
Observability: replace cAdvisor (which resolves only the root cgroup on the
contour host — separate-XFS /var/lib/docker) with the otelcol docker_stats
receiver, which reads per-container CPU/memory/network straight from the Docker
API and works the same in prod. The collector joins the host docker group
(DOCKER_GID, default 989) and mounts the socket read-only; its metrics flow out
through the existing prometheus exporter, so the cAdvisor scrape job and the
privileged cAdvisor service are removed. The Resources dashboard panels are
retargeted to the docker_stats metric names (container_name label;
container.cpu.utilization/100 == cores).
Container limits: apply deploy.resources.limits (honoured by Compose v2) across
the contour and pin GOMAXPROCS to the CPU limit on the Go services so the runtime
matches the cgroup quota. Starting values are generous over the R2 peak (~1 core /
<=100 MiB per app service) to avoid skewing or OOM-killing the measurement run;
they are tightened to the agreed prod sizing after the final stress run (R7
Round 2). The privileged VPN sidecar is left unconstrained.
New scrabble/loadtest module (the pre-release stress harness): seeds 1000 guest +
10000 durable accounts with pre-created sessions directly in Postgres (token hash
matches backend/internal/session), drives virtual players through the edge protocol
(real 2-4p games assembled via invitations, mid-ranked legal moves generated locally
by the embedded scrabble-solver — the edge carries no board, so the client replays
history), plus nudge/chat/check-word/draft/profile/stats and a gateway-hammer that
verifies the rate limiter. Prints a trip-report summary (per-op latency percentiles,
result codes, live-event tally). Go unit tests cover the pure pieces; the DAWG-backed
move test runs under BACKEND_DICT_DIR.
Contour: add cAdvisor + postgres_exporter + a 'Scrabble - Resources' Grafana
dashboard and the two Prometheus scrape jobs, for the R2/R7 stress-run resource
baseline.
CI: gate ./loadtest/... (path filter + vet/build/test). Docs: TESTING, ARCHITECTURE,
project CLAUDE repo layout.
Ilia Denisov