Erro no build do docker-compose.yml

Segue o erro retornado quando eu tento rodar o comando "docker-compose build"

ERROR: The Compose file '.\docker-compose.yml' is invalid because: services.nginx.ports contains an invalid type, it should be an array

segue o código do arquivo docker-compose.yml:

version: '3' services: nginx: build: dockerfile: ./docker/nginx.dockerfile context: . image: douglasq/nginx container_name: nginx ports:

        - "80:80"
    networks: 
        - production-network

mongodb:
    image: mongo
    networks: 
        - production-network

node1:
    build:
        dockerfile: ./docker/alura-books.dockerfile
        context: .
    image: douglasq/alura-books
    container_name: alura-books-1
    ports:
        - "3000"
    networks: 
        - production-network

node2:
    build:
        dockerfile: ./docker/alura-books.dockerfile
        context: .
    image: douglasq/alura-books
    container_name: alura-books-2
    ports:
        - "3000"
    networks: 
        - production-network

node3:
    build:
        dockerfile: ./docker/alura-books.dockerfile
        context: .
    image: douglasq/alura-books
    container_name: alura-books-3
    ports:
        - "3000"
    networks: 
        - production-network

networks: production-network: driver: bridge