Docker 容器退出后，绑定安装文件夹中的文件似乎消失了

Question

我正在使用 docker-compose，我正在尝试了解如何配置我的 node_modules 文件夹。我无法理解文件如何与 Docker 中的卷或绑定挂载一起保存。这是我的项目设置：

user@computer:~/myprojects/deleteme$ tree
.
├── docker-compose.yml
└── frontend
    ├── Dockerfile
    └── package.json

docker-compose.yml

version: '3'

services:
  frontend:
    build: ./frontend
    volumes:
      - ./frontend:/app/frontend
    container_name: frontend

Dockerfile

FROM node:12-alpine

WORKDIR /app/frontend

RUN npm install

RUN echo "Node done!"
RUN touch foo
RUN ls

package.json

{
  "name": "deleteme",
  "version": "1.1.0",
  "repository": {
    "type": "git"
  },
  "scripts": {
  },
  "dependencies": {
    "npm-run-all": "4.1.5",
    "react": "16.13.1",
    "react-datetime": "2.16.3",
    "react-dom": "16.13.1",
    "react-router": "5.2.0",
    "react-router-dom": "5.2.0",
    "react-scripts": "3.4.1"
  }
}

当我docker-compose build --no-cache 时，我得到了

Building frontend
Step 1/6 : FROM node:12-alpine
 ---> 057fa4cc38c2
Step 2/6 : WORKDIR /app/frontend
 ---> Running in 81229692051b
Removing intermediate container 81229692051b
 ---> 0ef46ff4472d
Step 3/6 : RUN npm install
 ---> Running in cf7afc9d1f54
npm WARN saveError ENOENT: no such file or directory, open '/app/frontend/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 '/app/frontend/package.json'
npm WARN frontend No description
npm WARN frontend No repository field.
npm WARN frontend No README data
npm WARN frontend No license field.

up to date in 0.227s
found 0 vulnerabilities

Removing intermediate container cf7afc9d1f54
 ---> af6169ff583b
Step 4/6 : RUN echo "Node done!"
 ---> Running in e037c7bbd127
Node done!
Removing intermediate container e037c7bbd127
 ---> 843945701b93
Step 5/6 : RUN touch foo
 ---> Running in fc0663e95e48
Removing intermediate container fc0663e95e48
 ---> 48460f061742
Step 6/6 : RUN ls
 ---> Running in 594b7843bc8b
foo
package-lock.json
Removing intermediate container 594b7843bc8b
 ---> 6d4e09b0ff64
Successfully built 6d4e09b0ff64
Successfully tagged deleteme_frontend:latest

我不明白为什么package.json 还没有在容器的/app/frontend 中，因为我在docker-compose.yml 中指定了./frontend:/app/frontend。而且我不明白为什么foo 和package-lock.json 接缝会在容器存在后消失，因为如果我再次使用tree，我会得到

.
├── docker-compose.yml
└── frontend
    ├── Dockerfile
    └── package.json

Answer 1

您正在将文件挂载到容器运行时，显然一旦容器被删除，它将被删除。您必须在构建时添加这些文件（docker build），以便您的应用程序相关文件与图像一起存在，所以您的 dockerfile 应该是这样的

FROM node:12-alpine

WORKDIR /app/frontend

COPY ./frontend ./          <<---- here

RUN npm install

RUN echo "Node done!"
RUN touch foo
RUN ls

Answer 2

这是因为只有在容器运行时才会安装卷，而不是在构建映像时。您需要在Dockerfile 中使用COPY 命令在构建阶段从./frontend 添加文件。示例：

FROM node:12-alpine

WORKDIR /app/frontend
COPY frontend ./
RUN npm install