Dockerfile - npm install

Boa tarde!! Estou executando o build, mas está dando erro para instalar o npm install.

Step 5/7 : RUN npm install /var/www
 ---> Running in 8aeb0b11d574
npm WARN saveError ENOENT: no such file or directory, open '/var/www/package.json'
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN enoent ENOENT: no such file or directory, open '/var/www/package.json'
npm WARN www No description
npm WARN www No repository field.
npm WARN www No README data
npm WARN www No license field.

Direto no toolbox, eu tive que apontar o diretório:

docker run -d -p 8080:3000 -v "//c/Users/Biaggio/Desktop/docker/node_docker:/var/www" -w "/var/www/" node npm start

Como faço isso no dockerfile???

Comando executado:

docker build -f node.dockerfile -t rodrigo/node .