1 初始化项目

mkdir demo && cd demo
npm init -y 
npm i koa -s

package.json

{
  "private": true,
  "name": "myappp",
  "version": "1.0.0",
  "main": "app.js",
  "license": "ISC",
  "description": "myappp",
  "dependencies": {
    "koa": "^2.7.0"
  }
}

2 添加程序入口

//app.js
const Koa = require("koa");
const app = new Koa();
app.use((ctx) => {
  ctx.body = "Hello Docker";
});
app.listen(3000, () => {
  console.log("app started at http://localhost:3000/");
});

3 添加Dockerfile配置

#Dockerfile 

#制定node镜像的版本 
FROM node:10-alpine 

#移动当前目录下面的文件到app目录下 
ADD . /app/ 

#进入到app目录下面，类似cd 
WORKDIR /app 

#安装依赖 
RUN npm install 

#对外暴露的端口 
EXPOSE 3000 

#程序启动脚本 
CMD ["node", "app.js"]

4 生成镜像

# 定制镜像 
docker build -t mynode . 

# 运行 
docker run -p 3000:3000 -d mynode