如何在 docker 构建期间设置环境变量 [英] How do I set environment variables during the build in docker

问题描述

我试图在构建期间在 docker 容器中设置环境变量，但没有成功.使用运行命令时设置它们有效，但我需要在构建期间设置它们.

I'm trying to set environment variables in docker container during the build but without success. Setting them when using run command works but I need to set them during the build.

Dockerfile

FROM ubuntu:latest
ARG TEST_ENV=something

我用来构建的命令

docker build -t --build-arg TEST_ENV="test" myimage .

跑步

docker run -dit myimage

我正在使用检查可用的环境变量

I'm checking available environment variables by using

docker exec containerid printenv

结果是

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
HOSTNAME=e49c1abfd58b
TERM=xterm
no_proxy=*.local, 169.254/16
HOME=/root

TEST_ENV 不存在

TEST_ENV is not present

推荐答案

ARG 用于设置在 docker build 过程中使用的环境变量 - 它们不存在在最终图像中，这就是为什么您在使用 docker run 时看不到它们的原因.

ARG is for setting environment variables which are used during the docker build process - they are not present in the final image, which is why you don't see them when you use docker run.

您将 ARG 用于仅在构建映像时相关的设置，并且您从映像运行的容器不需要这些设置.您可以将 ENV 用于在构建期间和容器中使用的环境变量.

You use ARG for settings that are only relevant when the image is being built, and aren't needed by containers which you run from the image. You can use ENV for environment variables to use during the build and in containers.

有了这个 Dockerfile:

With this Dockerfile:

FROM ubuntu                                                                                                            
ARG BUILD_TIME=abc                                                                                                     
ENV RUN_TIME=123                                                                                                       
RUN touch /env.txt                                                                                                     
RUN printenv > /env.txt 

您可以像使用 docker build -t temp --build-arg BUILD_TIME=def . 一样覆盖构建参数.然后你会得到你所期望的:

You can override the build arg as you have done with docker build -t temp --build-arg BUILD_TIME=def .. Then you get what you expect:

> docker run temp cat /env.txt                                                                                         
HOSTNAME=b18b9cafe0e0                                                                                                  
RUN_TIME=123                                                                                                           
HOME=/root                                                                                                             
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin                                                      
BUILD_TIME=def                                                                                                         
PWD=/ 

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