从 docker --build-arg 命令获取版本时出现问题

Question

我试图通过传递“--build-arg VERSION =”来构建图像时获取版本，但页面显示默认版本：

应用程序版本将在 docker build… 命令中指定。通过赋予价值

ARG指令定义的VERSION变量

# Stage 1: Build the application
FROM node:alpine AS builder

# Set the argument for the application version
ARG VERSION

# Install tools and dependencies
RUN apk add --update curl && \
    rm -rf /var/cache/apk/*

# Set the working directory
WORKDIR /usr/app

# Copy application files
COPY ./package.json ./

# Install dependencies
RUN npm install

# Copy application files
COPY ./index.js ./

# Stage 2: Final image
FROM alpine

# Copy files from the build stage
COPY --from=builder /usr/app .

# Set the working directory
WORKDIR /usr/app

# Install Node.js
RUN apk --no-cache add nodejs npm

# Install Express.js
RUN npm install express

# Information about the internal container port on which the application listens
EXPOSE 8080

# Default command to start the container
CMD ["node", "index.js"]

# Set the environment variable for the application version
ENV VERSION=production.${VERSION:-v1.0}

const express = require('express');
const os = require('os');

const app = express();
const port = 8080;

app.get('/', (req, res) => {
  let response = `Server IP Address: ${getIPAddress()}\n`;
  response += `Server Name (hostname): ${os.hostname()}\n`;
  response += `Application Version: ${process.env.VERSION}\n`;
  res.send(response);
});

app.listen(port, () => {
  console.log(`The application is available on port ${port}`);
});

function getIPAddress() {
  const interfaces = os.networkInterfaces();
  for (const dev in interfaces) {
    const iface = interfaces[dev].filter(details => details.family === 'IPv4' && !details.internal);
    if (iface.length > 0) return iface[0].address;
  }
  return '0.0.0.0';
}

我这样使用推荐：

docker build --build-arg VERSION=2.0.0 -f Dockerfile10 -t local/base:v10 .

然后：

docker run -d -p 8090:8080 --name web10 local/base:v10

命令curl http://localhost:8090之后的结果 -> 它显示IP地址，主机名，但版本是Production.v1.0而不是传入--build-arg的2.0.0

Answer 1

这里有两个问题：

1. ENV

   需要先于

   CMD

   和

2. ARG

   需要与

   ENV

   处于同一阶段。

尝试这样的事情：

FROM node:alpine AS builder

RUN apk add --update curl && \
    rm -rf /var/cache/apk/*

WORKDIR /usr/app

COPY ./package.json ./

RUN npm install

COPY ./index.js ./

FROM alpine

WORKDIR /usr/app

COPY --from=builder /usr/app .

RUN apk --no-cache add nodejs npm

RUN npm install express

EXPOSE 8080

ARG VERSION
ENV VERSION=production.${VERSION:-v1.0}

CMD ["node", "index.js"]

我同意对你的问题的评论之一：看起来你真的不需要多阶段构建，因为你的

builder

阶段并没有真正做任何在最后阶段没有完成的事情。

但是，上面的

Dockerfile

至少可以工作。

Answer 2

您将 VERSION 构建参数传递给 Docker 构建过程，然后在 Node.js 应用程序中访问它的方式似乎可能存在问题。

Docker 构建参数：您在 Docker 构建过程中正确传递了 VERSION 参数

docker build --build-arg VERSION=2.0.0 -f Dockerfile10 -t local/base:v10


# Set the argument for the application version
ARG VERSION
...
# Set the environment variable for the application version
ENV VERSION=production.${VERSION:-v1.0}


console.log(`For conformation Application Version (before response): ${process.env.VERSION}`);

重建图像

docker build --build-arg VERSION=2.0.0 -f Dockerfile10 -t local/base:v10

运行容器

docker run -d -p 8090:8080 --name web10 local/base:v10

检查输出

curl http://localhost:8090