Dockerfile中的条件ENV [英] Conditional ENV in Dockerfile

问题描述

是否可以根据构建 ARG 的值在Dockerfile中有条件地设置 ENV 变量？

Is it possible to conditionally set an ENV variable in a Dockerfile based on the value of a build ARG?

例如：

ARG BUILDVAR=sad
ENV SOMEVAR=if $BUILDVAR -eq "SO"; then echo "hello"; else echo "world"; fi

更新：基于Mario答案的当前用法：

Update: current usage based on Mario's answer:

ARG BUILD_ENV=prod
ENV NODE_ENV=production
RUN if [ "${BUILD_ENV}" = "test" ]; then export NODE_ENV=development; fi

但是，运行-build-arg BUILD_ENV = test 然后进入主机，我仍然得到

However, running with --build-arg BUILD_ENV=test and then going onto the host, I still get

docker run -it mycontainer bin/bash
[root@brbqw1231 /]# echo $NODE_ENV
production

推荐答案

是的，可以，但是您需要使用build参数作为标志。您可以使用外壳程序的参数扩展功能来检查条件。这是概念验证的Docker文件：

Yes, it is possible, but you need to use your build argument as flag. You can use parameter expansion feature of shell to check condition. Here is a proof-of-concept Docker file:

FROM debian:stable
ARG BUILD_DEVELOPMENT
# if --build-arg BUILD_DEVELOPMENT=1, set NODE_ENV to 'development' or set to null otherwise.
ENV NODE_ENV=${BUILD_DEVELOPMENT:+development}
# if NODE_ENV is null, set it to 'production' (or leave as is otherwise).
ENV NODE_ENV=${NODE_ENV:-production}

测试版本：

docker build --rm -t env_prod ./
...
docker run -it env_prod bash
root@2a2c93f80ad3:/# echo $NODE_ENV 
production
root@2a2c93f80ad3:/# exit
docker build --rm -t env_dev --build-arg BUILD_DEVELOPMENT=1 ./
...
docker run -it env_dev bash
root@2db6d7931f34:/# echo $NODE_ENV
development

这篇关于Dockerfile中的条件ENV的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！