version: '3'

services:

  # Service to download a model file.
  downloader:
    image: busybox
    # The command extracts the model filename from MODEL_URL and downloads it if it doesn't exist.
    command: /bin/sh -c "LLM_MODEL_FILE=$(basename ${MODEL_URL}); if [ ! -f /models/$LLM_MODEL_FILE ]; then wget -O /models/$LLM_MODEL_FILE ${MODEL_URL}; fi"
    # Mount a local directory to store the downloaded model.
    volumes:
      - ./models:/models

  # Service to wait for the downloader service to finish downloading the model.
  wait-for-downloader:
    image: busybox
    # The command waits until the model file (specified in MODEL_URL) exists.
    command: /bin/sh -c "LLM_MODEL_FILE=$(basename ${MODEL_URL}); echo 'Waiting for downloader to finish'; while [ ! -f /models/$LLM_MODEL_FILE ]; do sleep 1; done; echo 'Model downloaded!'"
    # Specifies that this service should start after the downloader service has started.
    depends_on:
      downloader:
        condition: service_started
    # Mount the same local directory to check for the downloaded model.
    volumes:
      - ./models:/models

  # Service to run the Llama web application.
  llm:
    image: ghcr.io/abetlen/llama-cpp-python:latest
    # Mount the directory that contains the downloaded model.
    volumes:
      - ./models:/models
    environment:
      # Specify the path to the model for the web application.
      MODEL: /models/llama-2-7b-chat.ggmlv3.q4_1.bin
    labels:
      # Instead of using the Host rule, set a PathPrefix rule
      - "traefik.http.routers.web.rule=PathPrefix(`/inference/llm`)"
      # This tells Traefik where to forward the traffic for this route.
      - "traefik.http.routers.web.service=llm"
    # Define a service for the llm and specify its load balancer configuration
      - "traefik.http.services.llm-service.loadbalancer.server.port=8000"

      - "traefik.http.middlewares.strip-llm-prefix.stripprefix.prefixes=/inference/llm"
      - "traefik.http.routers.web.middlewares=strip-llm-prefix"
    # Health check configuration
    healthcheck:
      test: ["CMD", "wget", "--quiet", "--tries=1", "--spider", "http://localhost:8000"]
      interval: 30s
      timeout: 10s
      retries: 3
      start_period: 30s
    # Restart policy configuration
    restart: on-failure
    # Specifies that this service should start only after wait-for-downloader has completed successfully.
    depends_on:
      wait-for-downloader:
        condition: service_completed_successfully
    # Connect this service to two networks: inference_net and traefik_public.
    networks:
      - inference_net
      - traefik_public
  
  # Service for Traefik, a modern HTTP reverse proxy and load balancer.
  traefik:
    image: traefik:v2.5
    command:
      # Enable the Traefik API dashboard without TLS (not recommended for production).
      - "--api.insecure=true"
      # Enable Traefik to use Docker as a provider.
      - "--providers.docker=true"
      # Do not expose services by default. Explicitly specify in each service if it should be exposed.
      - "--providers.docker.exposedbydefault=false"
      # Specify the default entry point on port 80.
      - "--entrypoints.web.address=:80"
    ports:
      # Map port 80 in the container to port 80 on the host.
      - "80:80"
      # Map port 8080 in the container (Traefik's dashboard) to port 8080 on the host.
      - "8080:8080"
    # Mount the Docker socket to allow Traefik to listen to Docker's API.
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
    # Connect this service to the traefik_public network.
    networks:
      - traefik_public

# Define networks used in this docker-compose file.
networks:
  # Network for the llm service (used for inference).
  inference_net:
  # Public-facing network that Traefik uses. Marked as external to indicate it may be defined outside this file.
  traefik_public:
    external: true