# Docker Swarm stack for prod — the autoscaling successor to docker-compose.yml
# on that host (beta and LAN dev stay on plain compose; deploy.sh routes by the
# /etc/thermograph/deploy-mode marker). Two-image world: web/worker run the
# backend image, frontend its own — per-service tags, same contract as compose.
#
# Deployed by deploy/stack/deploy-stack.sh, which:
#   - sources /etc/thermograph.env (SOPS-rendered) so ${VARS} here interpolate,
#   - installs a uid-10001-readable copy at /etc/thermograph/stack.env that
#     deploy/stack/env-entrypoint.sh sources inside each app task (set-if-unset,
#     so `environment:` blocks below always win) — this replaces compose's
#     env_file:, which `docker stack deploy` does not support,
#   - runs migrations as a ONE-SHOT task before rolling (RUN_MIGRATIONS=0 in
#     every replica — N replicas must never race Alembic),
#   - manages the loopback LB bridge (see lb/README note below): Swarm's mesh
#     can only publish on 0.0.0.0 (would expose the plaintext app un-fronted),
#     so nothing here has `ports:`. A plain container on this attachable
#     overlay binds 127.0.0.1:8137/8080 for the host Caddy and proxies to the
#     service VIPs — Swarm's VIP does the actual load balancing across
#     replicas.
#
# Scaling model: `web` is stateless (ROLE=web never runs the notifier) and
# scales 1..N — the autoscaler service adjusts replicas between
# WEB_MIN_REPLICAS/WEB_MAX_REPLICAS on task CPU. `worker` owns the notifier +
# scheduler: exactly 1 replica, with the cluster-wide Postgres advisory lock
# (THERMOGRAPH_SINGLETON_PG) as belt-and-suspenders. `db` is exactly 1 — a
# database does not scale by container count on one host; its levers are
# DB_CPUS/DB_MEMORY (and, multi-host later, Patroni replicas per the topology
# doc). Everything is pinned to the manager node: all volumes are local to
# prod today. That constraint is the ONLY thing to relax when a second app
# node joins.
#
# TIMESCALEDB_IMAGE must be the exact image (digest-pinned) the compose stack
# was running — see hazard #7 in the hop-1 runbook: a floating tag can change
# the extension minor under an existing volume. deploy-stack.sh resolves it
# from the running/last-known container automatically.

services:
  db:
    image: ${TIMESCALEDB_IMAGE:?required}
    environment:
      POSTGRES_USER: thermograph
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:?required}
      POSTGRES_DB: thermograph
      DB_MEMORY: ${DB_MEMORY:-16g}
    volumes:
      - pgdata:/var/lib/postgresql
      - /opt/thermograph/infra/deploy/db/init:/docker-entrypoint-initdb.d:ro
    networks:
      - internal
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U thermograph -d thermograph"]
      interval: 5s
      timeout: 5s
      retries: 10
    deploy:
      replicas: 1
      placement:
        constraints: ["node.role == manager"]
      resources:
        limits:
          cpus: "${DB_CPUS:-4}"
          memory: ${DB_MEMORY:-16g}
      restart_policy:
        condition: on-failure

  web:
    image: ${REGISTRY_HOST:-git.thermograph.org}/${BACKEND_IMAGE_PATH:-emi/thermograph/backend}:${BACKEND_IMAGE_TAG:?required}
    entrypoint: ["/host/env-entrypoint.sh"]
    environment:
      THERMOGRAPH_DATABASE_URL: postgresql+asyncpg://thermograph:${POSTGRES_PASSWORD}@db:5432/thermograph
      THERMOGRAPH_BASE: /
      PORT: 8137
      THERMOGRAPH_SERVICE_ROLE: backend
      THERMOGRAPH_FRONTEND_BASE_INTERNAL: http://frontend:8080
      WORKERS: ${WEB_WORKERS:-4}
      THERMOGRAPH_DATA_DIR: /state
      # web NEVER runs the notifier/scheduler, even if it would win election —
      # that's the worker service's job. This is what makes web replicas safe.
      THERMOGRAPH_ROLE: web
      RUN_MIGRATIONS: "0"
      # Overlay tasks reach the HOST's Postfix via the docker_gwbridge gateway,
      # not the compose bridge's 172.19.0.1 (an overlay has no host gateway).
      # provision-mail.sh's DOCKER_MAIL_GATEWAY/SUBNET cover this listener.
      THERMOGRAPH_SMTP_HOST: ${STACK_SMTP_HOST:-172.18.0.1}
    volumes:
      - appdata:/state
      - applogs:/app/logs
      - /opt/thermograph/infra/deploy/stack/env-entrypoint.sh:/host/env-entrypoint.sh:ro
      - /etc/thermograph/stack.env:/host/thermograph.env:ro
    networks:
      - internal
    deploy:
      replicas: ${WEB_MIN_REPLICAS:-1}
      placement:
        constraints: ["node.role == manager"]
      resources:
        limits:
          cpus: "${WEB_CPUS:-4}"
      restart_policy:
        condition: on-failure
      update_config:
        # New task must pass the image's own HEALTHCHECK before the old one
        # stops — zero-downtime single-service rolls.
        order: start-first
        failure_action: rollback

  worker:
    image: ${REGISTRY_HOST:-git.thermograph.org}/${BACKEND_IMAGE_PATH:-emi/thermograph/backend}:${BACKEND_IMAGE_TAG:?required}
    entrypoint: ["/host/env-entrypoint.sh"]
    environment:
      THERMOGRAPH_DATABASE_URL: postgresql+asyncpg://thermograph:${POSTGRES_PASSWORD}@db:5432/thermograph
      THERMOGRAPH_BASE: /
      PORT: 8137
      THERMOGRAPH_SERVICE_ROLE: backend
      THERMOGRAPH_FRONTEND_BASE_INTERNAL: http://frontend:8080
      WORKERS: "1"
      THERMOGRAPH_DATA_DIR: /state
      THERMOGRAPH_ROLE: worker
      # Cluster-wide Postgres advisory lock, not the host flock: correct at
      # replicas=1 today and stays correct if a second worker ever appears.
      THERMOGRAPH_SINGLETON_PG: "1"
      RUN_MIGRATIONS: "0"
      THERMOGRAPH_SMTP_HOST: ${STACK_SMTP_HOST:-172.18.0.1}
    volumes:
      - appdata:/state
      - applogs:/app/logs
      - /opt/thermograph/infra/deploy/stack/env-entrypoint.sh:/host/env-entrypoint.sh:ro
      - /etc/thermograph/stack.env:/host/thermograph.env:ro
    networks:
      - internal
    deploy:
      replicas: 1
      placement:
        constraints: ["node.role == manager"]
      resources:
        limits:
          cpus: "${WORKER_CPUS:-2}"
      restart_policy:
        condition: on-failure

  frontend:
    image: ${REGISTRY_HOST:-git.thermograph.org}/${FRONTEND_IMAGE_PATH:-emi/thermograph/frontend}:${FRONTEND_IMAGE_TAG:?required}
    entrypoint: ["/host/env-entrypoint.sh"]
    environment:
      THERMOGRAPH_BASE: /
      PORT: 8080
      THERMOGRAPH_SERVICE_ROLE: frontend
      THERMOGRAPH_API_BASE_INTERNAL: http://web:8137
    volumes:
      - /opt/thermograph/infra/deploy/stack/env-entrypoint.sh:/host/env-entrypoint.sh:ro
      - /etc/thermograph/stack.env:/host/thermograph.env:ro
    networks:
      - internal
    deploy:
      replicas: 1
      placement:
        constraints: ["node.role == manager"]
      resources:
        limits:
          cpus: "${FRONTEND_CPUS:-2}"
      restart_policy:
        condition: on-failure
      update_config:
        order: start-first
        failure_action: rollback

  # Scales `web` between WEB_MIN_REPLICAS and WEB_MAX_REPLICAS on sustained
  # task CPU (docker stats on this node — every task is pinned here today).
  # Deliberately a dumb shell loop with hysteresis + cooldown, not an
  # autoscaling framework: Swarm has no native autoscaler and this workload
  # doesn't justify one (topology doc §6 — declarative scaling as a feature).
  autoscaler:
    image: docker:27-cli
    entrypoint: ["/bin/sh", "/host/autoscale.sh"]
    environment:
      STACK_NAME: ${STACK_NAME:-thermograph}
      MIN_REPLICAS: ${WEB_MIN_REPLICAS:-1}
      MAX_REPLICAS: ${WEB_MAX_REPLICAS:-3}
      # Thresholds are avg docker-stats CPU% PER TASK (host-core-relative: 100
      # = one full core). Up fast, down slow.
      SCALE_UP_CPU: ${SCALE_UP_CPU:-220}
      SCALE_DOWN_CPU: ${SCALE_DOWN_CPU:-60}
      POLL_SECONDS: ${POLL_SECONDS:-15}
      UP_SAMPLES: ${UP_SAMPLES:-3}
      DOWN_SAMPLES: ${DOWN_SAMPLES:-20}
      COOLDOWN_SECONDS: ${COOLDOWN_SECONDS:-180}
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - /opt/thermograph/infra/deploy/stack/autoscale.sh:/host/autoscale.sh:ro
    networks:
      - internal
    deploy:
      replicas: 1
      placement:
        constraints: ["node.role == manager"]
      resources:
        limits:
          cpus: "0.2"
          memory: 64m
      restart_policy:
        condition: any

networks:
  internal:
    driver: overlay
    # Attachable so the loopback LB bridge (a PLAIN container — only plain
    # containers can bind 127.0.0.1; Swarm port configs cannot) can join and
    # reach the service VIPs.
    attachable: true

volumes:
  # External and explicitly named: the real stack REUSES the volumes the
  # compose stack created (same data, zero migration). deploy-stack.sh's test
  # mode points these at throwaway names instead.
  pgdata:
    external: true
    name: ${PGDATA_VOLUME:-thermograph_pgdata}
  appdata:
    external: true
    name: ${APPDATA_VOLUME:-thermograph_appdata}
  applogs:
    external: true
    name: ${APPLOGS_VOLUME:-thermograph_applogs}