docker-compose build problemas

Quando executo o comando docker-compose up me exibe a seguinte mensagem de erro

ERROR: yaml.scanner.ScannerError: mapping values are not allowed here
  in ".\docker-compose.yml", line 6, column 16

ja verifiquei meu arquivo docker-compose.yml entrentanto ele parece estar ok

de qlqr maneira tentei executar o comando docker-compose build, ele parece executar pois nao retorna nenhum erro.

alguem tem alguma ideia do que possa estar ocorrendo?

meu 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
    depends_on: 
      - "node1"
      - "node2"
      - "node3"

  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
      depends_on:
        - "mongodb"

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

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

networks: 
    production-network:
        driver: bridge