services:
  nats-server1:
    image: nats:latest
    container_name: nats-server1
    command: ["-c", "/etc/nats/nats-server.conf", "--server_name", "nats-server1"]
    ports:
      - "4222:4222"   # Client Traffic
      - "9222:9222"   # Websockets (Julia/Web UI)
      - "6222:6222"   # Cluster Routing Mesh
    volumes:
      - ./nats-server.conf:/etc/nats/nats-server.conf:ro
      - ./data/nats-jetstream:/data/nats-jetstream
    restart: unless-stopped


  # ==========================================
  # NATS UI Management
  # ==========================================
  # You only need the UI running on one of your machines
  nats-ui:
    image: ghcr.io/nats-nui/nui:latest
    volumes:
      - ./nats_ui_db:/db
    ports:
      - "31311:31311"
    restart: unless-stopped



# to make 3-node nats. copy docker-compose.yml and nats-server.conf to PC2 and PC3


# Important Architectural Notes for Scaling Later
# When you eventually uncomment nats-server2 and nats-server3, keep these structural behaviors in mind:

# The Quorum Rule (Raft): JetStream requires a strict majority to achieve quorum and allow stream writes.

# With 1 node running, your cluster size is effectively 1, so quorum is met.

# If you bring up a second node, your cluster size becomes 2, meaning you need both nodes online to function. Never run a 2-node JetStream cluster in production.

# When you decide to scale up, uncomment both nats-server2 and nats-server3 at the same time to establish a stable 3-node cluster (where 2 out of 3 nodes must be alive).

# Stream Replicas: When you create a Stream using the CLI or code in a 3-node cluster, you can specify --replicas 3. This instructs NATS to automatically mirror that stream’s data chunks across all 3 underlying storage engines over the internal 6222 mesh network.


# How Your Applications Connect Now
# When your application workers (like your Julia or Rust processes) connect to a multi-node cluster, you should provide all three host IPs in the client connection string:
# nats://192.168.1.101:4222,nats://192.168.1.102:4222,nats://192.168.1.103:4222
# If PC 1 goes down completely, your application client will automatically reconnect to PC 2 or PC 3 within milliseconds, and JetStream data processing will continue without losing a single message.