具有环境变量的ENTRYPOINT不接受新参数 [英] ENTRYPOINT with environment variables is not acepting new params

问题描述

我们正在创建一个简单的 Dockerfile ，该文件的最后一行是

We are creating a simple Dockerfile, the last line of that file is

 ENTRYPOINT ["sh", "-c", "spark-submit --master $SPARK_MASTER script.py"]

script.py 是一个简单的pyspark应用程序（对本次讨论不重要），该pyspark应用程序接收了一些我们要尝试的参数如下使用 docker 命令传递

The script.py is a simple pyspark app (is not important for this discussion), this pyspark app receives some parameters that we are trying to pass using the docker command as follows

 docker run --rm my_spark_app_image --param1 something --param2 something_else

但是 script.py 没有得到任何参数，即执行了容器：

But script.py is not getting any parameter, i.e. the container executed:

 spark-submit --master $SPARK_MASTER script.py

预期的行为是容器执行：

The expected behaviour is that the container executes:

 spark-submit --master $SPARK_MASTER script.py --param1 something --param2 something_else

我在做什么错了？

推荐答案

/ bin / sh -c 只需要一个参数即可运行脚本。该参数之后的所有内容都是一个外壳变量 $ 0 ， $ 1 等，可以由脚本进行解析。虽然您可以使用 / bin / sh -c 语法来做到这一点，但它很尴尬，以后也不会与您一起成长。

The /bin/sh -c only takes one argument, the script to run. Everything after that argument is a a shell variable $0, $1, etc, that can be parsed by the script. While you could do this with the /bin/sh -c syntax, it's awkward and won't grow with you in the future.

而不是尝试在那里解析变量，我将其移动到图像中包含的entrypoint.sh中：

Rather than trying to parse the variables there, I'd move this into an entrypoint.sh that you include in your image:

#!/bin/sh
exec spark-submit --master $SPARK_MASTER script.py "$@"

，然后更改Dockerfile来定义：

And then change the Dockerfile to define:

COPY entrypoint.sh /entrypoint.sh
ENTRYPOINT ["/entrypoint.sh"]

exec 语法用spark-submit进程替换PID 1中的shell脚本，从而允许信号通过。 $ @ 将通过 docker run 的任何参数传递，如果您在其中有空格，则引用每个参数。参数。并且由于它是由Shell脚本运行的，因此 $ SPARK_MASTER 会得到扩展。

The exec syntax replaces the shell script in PID 1 with the spark-submit process, which allows signals to be passed through. The "$@" will pass through any arguments from docker run, with each arg quoted in case you have spaces in the parameters. And since it's run by a shell script, the $SPARK_MASTER will be expanded.

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