如果我们在 entrypoint.sh 中引导它，应用程序是否会以 PID 1 运行，并且会收到信号吗? [英] Will the application run as PID 1 and will signals be received if we bootstrap it in a entrypoint.sh?

问题描述

启动服务是个好习惯

CMD ["/go/bin/myapp"]

而不是

CMD /go/bin/myapp

在第一种方式中，SIGTERM 被应用程序捕获，而在第二种方式中，它们被底层的 /bin/sh 脚本捕获，该脚本不会将它们转发给服务.我从 https 了解到这一点://forums.docker.com/t/docker-run-cannot-be-killed-with-ctrl-c/13108/2.

In the first way, SIGTERMs are caught by the applicaiton, while in the second way, they are caught by the underlying /bin/sh script, which does not forward them to the service. I learned this from https://forums.docker.com/t/docker-run-cannot-be-killed-with-ctrl-c/13108/2.

现在我想知道 CMD ["..."] 是否完全等同于将 ... 放入 /entrypoint.sh 脚本并调用 CMD ["/entrypoint.sh"]?现在子应用程序是否也会作为 PID 1 运行并因此接收所有信号?

Now I am wondering if CMD ["..."] is completely equivalent to putting ... in an /entrypoint.sh script and calling CMD ["/entrypoint.sh"]? Will now child applications also be running as PID 1 and therefore receive all signals?

作为一个具体的例子，我想创建一个脚本:

As a concrete example, I want to create a script with:

envsubst < /etc/nginx/conf.d/site.template > /etc/nginx/conf.d/default.conf
&&
nginx -g 'daemon off;'

并在我的 Dockerfile 末尾调用 CMD ["/entrypoint.sh"].这安全吗?尽管脚本中有多个命令(envsubst 和 ngingx)，nginx 仍会以 PID 1 运行吗?

And call CMD ["/entrypoint.sh"] at the end of my Dockerfile. Is this safe and will nginx run as PID 1 despite that there are multiple commands (envsubst and ngingx) in the script?

这件事让我很困惑，我正试图弄清楚何时以及何时不使用 tini (https://github.com/krallin/tini).

This matter confuses me and I am trying to figure out when and when not to use tini (https://github.com/krallin/tini).

推荐答案

这是我尝试遵循 MySQL 5.7 Dockerfile 确实...但带有 Nginx 映像.

Here is my try to follow what also the MySQL 5.7 Dockerfile does... but with an Nginx image.

Dockerfile:

FROM nginx:latest
COPY docker-entrypoint.sh /usr/local/bin/
RUN chmod 777 /usr/local/bin/docker-entrypoint.sh

ENTRYPOINT ["docker-entrypoint.sh"] 
EXPOSE 80
CMD ["nginx", "-g", "daemon off;"]

docker-entrypoint.sh:

#!/bin/bash
set -e

echo "preparing..."

exec "$@"

我们的想法是在 docker-entrypoint.sh 脚本中做任何准备工作，然后使用 exec "$@" 将信号传递给 <代码>CMD.(这意味着你必须在 docker 中使用 envsubst </etc/nginx/conf.d/site.template >/etc/nginx/conf.d/default.conf-entrypoint.sh)

The idea is to do anything needed as a preparation inside the docker-entrypoint.sh script and with exec "$@" you then pass the signals to the CMD. (This means that you will have to use envsubst < /etc/nginx/conf.d/site.template > /etc/nginx/conf.d/default.conf inside docker-entrypoint.sh)

相关示例到 Dockerfile 文档的链接:如果您需要为单个可执行文件编写启动脚本，您可以使用 exec 和 gosu 命令...

Link of relevant example to Dockerfile docs: If you need to write a starter script for a single executable, you can ensure that the final executable receives the Unix signals by using exec and gosu commands...

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