docker-compose.yml

services:
  asyncdb-1:
    # One image between the three nodes: a service that names a build of its own is another
    # concurrent build of this same Dockerfile, blind to the layers the others are committing.
    # The localhost/ prefix is what tells podman-compose the image is built here, not pulled.
    build: .
    image: localhost/asyncdb
    container_name: asyncdb-1
    environment:
      # Where etcd answers, and this node as the other nodes reach it. Nodes talk to the API port
      # directly rather than through the nginx the browser uses.
      - ASYNCDB_ETCD=http://etcd:2379
      - ASYNCDB_NODE=http://asyncdb-1:8080
      # Every zone holds a copy of every record. Two zones here rather than three, so that this is
      # a cluster which both partitions — between the two nodes of zone one — and replicates: node
      # three is zone two on its own, and holds every record the other two hold between them.
      - ASYNCDB_ZONE=one
    ports:
      - 8080:80
    # The store, kept across a container being recreated so that a node comes back holding what
    # it wrote rather than empty.
    volumes:
      - asyncdb-1-data:/var/lib/asyncdb
    depends_on:
      - etcd
  asyncdb-2:
    image: localhost/asyncdb
    container_name: asyncdb-2
    environment:
      - ASYNCDB_ETCD=http://etcd:2379
      - ASYNCDB_NODE=http://asyncdb-2:8080
      - ASYNCDB_ZONE=one
    ports:
      - 8081:80
    # The store, kept across a container being recreated so that a node comes back holding what
    # it wrote rather than empty.
    volumes:
      - asyncdb-2-data:/var/lib/asyncdb
    depends_on:
      - etcd
  asyncdb-3:
    image: localhost/asyncdb
    container_name: asyncdb-3
    environment:
      - ASYNCDB_ETCD=http://etcd:2379
      - ASYNCDB_NODE=http://asyncdb-3:8080
      - ASYNCDB_ZONE=two
    ports:
      - 8082:80
    # The store, kept across a container being recreated so that a node comes back holding what
    # it wrote rather than empty.
    volumes:
      - asyncdb-3-data:/var/lib/asyncdb
    depends_on:
      - etcd
  etcd:
    image: quay.io/coreos/etcd:v3.5.9
    container_name: etcd
    environment:
      - ETCD_NAME=etcd-node
      - ETCD_DATA_DIR=/etcd-data
      - ETCD_LISTEN_CLIENT_URLS=http://0.0.0.0:2379
      - ETCD_ADVERTISE_CLIENT_URLS=http://etcd:2379
    ports:
      - 2379:2379
    volumes:
      - /tmp/etcd-data:/etcd-data:Z
    command:
      - /usr/local/bin/etcd

volumes:
  asyncdb-1-data:
  asyncdb-2-data:
  asyncdb-3-data: