# The cluster SPEC.md F-08 describes, shrunk onto one machine: several Nodes
# behind one entry point, all serving the same shared directory and reaching
# the same databases.
x-node: &node
  build: .
  image: workers-rb
  environment:
    # A Tenant answers at `<tenant>.workers.test` as well as at `/<tenant>`,
    # so both routing forms can be shown without owning a real domain.
    WORKERS_BASE_DOMAIN: workers.test
    # Every Node reads and writes every Tenant's database, which one server
    # for all three satisfies without anything between them: a write from any
    # of them is there for the next request wherever it lands.
    WORKERS_DB_URL: http://databases:8080
    WORKERS_DB_ADMIN_URL: http://databases:8081
  volumes:
    # Tenants are published by placing files, so the directory is mounted
    # rather than baked in: an edit here reaches the next request on every
    # Node. `rake dev:publish` copies `examples/` in.
    - ./app:/app:ro
  depends_on:
    databases:
      condition: service_healthy

services:
  # Every Tenant's databases, held where all three Nodes reach them. A Node
  # names the database it means in the Host header, which is where this reads
  # it, so one server holds them all without a name per database to resolve.
  databases:
    image: ghcr.io/tursodatabase/libsql-server:v0.24.32
    command: [ "/bin/sqld", "--enable-namespaces", "--disable-default-namespace" ]
    environment:
      SQLD_DB_PATH: /var/lib/sqld
      SQLD_ADMIN_LISTEN_ADDR: 0.0.0.0:8081
      # Left at its default of an hour, the write-ahead log of a database
      # under load grows for that hour: SQLite finishes a checkpoint only
      # when no reader is holding the log, and a busy database never offers
      # that. This is short enough that the quiet between bursts is used.
      # charts/workers-rb/README.md says how to choose it for traffic that is
      # not this demo's.
      SQLD_CHECKPOINT_INTERVAL_S: "30"
    volumes:
      - databases:/var/lib/sqld
    healthcheck:
      # Asked on the port that serves statements rather than the one that
      # manages databases, so what it answers for is the path a Tenant uses.
      # The image carries no HTTP client; bash reaches it on its own.
      #
      # This says whether the server is serving, and nothing about any one
      # database: a Tenant's own can stop answering while this stays green,
      # which is why the Host gives up on that one itself (SPEC B-34).
      #
      # Compose only records the answer — it restarts nothing, whatever
      # `restart:` says. Acting on it belongs to whatever runs the workload;
      # under Kubernetes this is the liveness probe and the restart is the
      # platform's.
      test: [ "CMD", "bash", "-c",
              'exec 3<>/dev/tcp/127.0.0.1/8080; printf "GET /health HTTP/1.0\r\n\r\n" >&3; head -1 <&3 | grep -q 200' ]
      interval: 5s
      timeout: 3s
      start_period: 15s
      retries: 5

  proxy:
    image: caddy:2-alpine
    ports:
      # The cluster's one external address. `WORKERS_PORT` moves it, for a
      # machine already running something of its own on 9292.
      - "${WORKERS_PORT:-9292}:80"
    volumes:
      - ./Caddyfile:/etc/caddy/Caddyfile:ro
    depends_on:
      node-a:
        condition: service_healthy
      node-b:
        condition: service_healthy
      node-c:
        condition: service_healthy

  # `Env.node` reads the hostname the operating system reports, so each Node is
  # given one an operator can recognise rather than a container id.
  node-a:
    <<: *node
    hostname: node-a

  node-b:
    <<: *node
    hostname: node-b

  node-c:
    <<: *node
    hostname: node-c

volumes:
  databases: