如何在不使Dockerfile混乱的情况下加载多个环境变量? [英] How to load several environment variables without cluttering the Dockerfile?

问题描述

我正在处理一个简单的具有大量环境变量的Docker映像.您是否可以像docker-compose一样导入环境变量文件?我在Docker文件文档中找不到关于此的任何内容.

I am working on a simple Docker image that has a large number of environment variables. Are you able to import an environment variable file like with docker-compose? I cannot find anything about this in the docker file documentation.

Dockerfile

FROM python:3.6

ENV ENV1 9.3
ENV ENV2 9.3.4
...

ADD . /

RUN pip install -r requirements.txt

CMD [ "python", "./manager.py" ]

我想重新表达这个问题的一个好方法是:如何有效地在Dockerfile中加载多个环境变量?如果您无法加载文件，则无法将docker文件提交到GitHub.

I guess a good way to rephrase the question would be: how do you efficiently load multiple environment variables in a Dockerfile? If you are not able to load a file, you would not be able to commit a docker file to GitHub.

推荐答案

是的，您可以通过以下两种方式进行此操作.

Yes, there are a couple of ways you can do this.

在Docker Compose中，您可以在文件本身中提供环境变量，或指向外部env文件:

In Docker Compose, you can supply environment variables in the file itself, or point to an external env file:

# docker-compose.yml
version: '2'
services:

  service-name:
    image: service-app
    environment:
    - GREETING=hello
    env_file:
    - .env

顺便说一句，一个与之相关的不错的功能是，您可以使用多个Compose文件，随后的每个文件都添加到另一个文件中.因此，如果上述内容定义了基础，则可以执行此操作(例如，针对每个运行时环境):

Incidentally, one nice feature that is somewhat related is that you can use multiple Compose files, with each subsequent one adding to the other. So if the above were to define a base, you can then do this (e.g. per run-time environment):

# docker-compose-dev.yml
version: '2'
services:

  service-name:
    environment:
    - GREETING=goodbye

然后您可以运行它:

docker-compose -f docker-compose.yml -f docker-compose-dev.yml up

仅限Docker

仅在Docker中执行此操作，请使用入口点或命令运行中间脚本，因此:

Docker only

To do this in Docker only, use your entrypoint or command to run an intermediate script, thus:

#Dockerfile

....

ENTRYPOINT ["sh", "bin/start.sh"]

然后在您的启动脚本中:

And then in your start script:

#!/bin/sh

source .env

python /manager.py

我曾经使用此相关答案作为过去对自己的有用参考.

I've used this related answer as a helpful reference for myself in the past.

为了扩大我在评论中的观点，如果您将入口点设为shell或Python脚本，则 Unix信号(停止，终止等)将不会传递到您的进程中.这是因为该脚本将成为进程ID 1 ，这使其成为所有其他进程的父进程.在容器中-在Linux/Unix中，期望此PID将信号转发给其子级，但是除非您明确实现，否则它不会发生.

To amplify my remark in the comments, if you make your entry point a shell or Python script, it is likely that Unix signals (stop, kill, etc) will not be passed onto your process. This is because that script will become process ID 1, which makes it the parent process of all other processes in the container - in Linux/Unix there is an expectation that this PID will forward signals to its children, but unless you explicitly implement that, it won't happen.

要纠正此问题，您可以安装一个初始化系统.我使用了Yelp的 dumb-init .如果您想更好地了解它，则此版本库还具有很多详细信息；如果您只是想安装后忘记"，则此存储库还提供了简单的安装说明.

To rectify this, you can install an init system. I use dumb-init from Yelp. This repo also features plenty of detail if you want to understand it a bit better, or simple install instructions if you just want to "install and forget".

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