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The official documentation can be found here.

problem with getting the version from the docker –build-arg command

I’m trying to get the version while building the image by passing "–build-arg VERSION=" but the page shows the default version:

the application version is to be specified in the docker build… command. by giving value

the VERSION variable defined by the ARG instructions

# 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';
}

I use commend like this:

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

then:

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

result after command curl http://localhost:8090 -> it shows ip address, hostname but version is production.v1.0 instead of 2.0.0 as passed in –build-arg

Tags:

2

Answers


  1. 0

    There are two issues here:

    1. the ENV needs to go before CMD and
    2. the ARG needs to go in the same stage as the ENV.

    Try something like this:

    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"]

    I agree with one of the comments on your question: it doesn’t look like you really need a multi-stage build because your builder stage is not really doing anything that’s not being done in the final stage.

    However, the Dockerfile above will at least work.

    enter image description here

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  2. 0

    It seems like there might be an issue with how you’re passing the VERSION build argument to the Docker build process and then accessing it within your Node.js application.

    Docker Build Argument: You’re correctly passing the VERSION argument during the Docker build process

    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}`);

    Rebuild Image

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

    Run Container

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

    Check Output

    curl http://localhost:8090
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