装载docker compose卷以重新加载代码时出错

我有一个简单的节点脚本,dockerfile和docker组成定义:

app/package.json软件包

{
  "name": "puppeteer-scrape",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "dependencies": {
    "nodemon": "^1.18.10",
  },
  "scripts": {
    "start": "nodemon scrape.js"
  }
}

应用程序/文档文件

FROM node:8.11.3

RUN mkdir -p /app
WORKDIR /app

COPY ./package* /app/
RUN npm install
COPY ./*.js /app/

CMD ["npm", "start"]

docker-compose.yml文件

version: '3'
services:
  app:
    build: app
    volumes:
     - .:/app

我想配置docker compose,以便在更改应用程序时重新运行脚本。

这个 official docker-compose tutorial 建议使用如上所述的体积定义来执行此操作。但是当我跑的时候 docker-compose up 我得到:

$ docker-compose up
app_1  | npm ERR! path /app/package.json
app_1  | npm ERR! code ENOENT
app_1  | npm ERR! errno -2
app_1  | npm ERR! syscall open
app_1  | npm ERR! enoent ENOENT: no such file or directory, open '/app/package.json'
app_1  | npm ERR! enoent This is related to npm not being able to find a file.
app_1  | npm ERR! enoent 
app_1  | 
app_1  | npm ERR! A complete log of this run can be found in:
app_1  | npm ERR!     /root/.npm/_logs/2019-03-02T23_54_53_560Z-debug.log

似乎应用程序目录被覆盖了,或者 npm start 正在复制应用程序之前调用。正确的配置方法是什么?