从docker容器运行docker命令(Running docker command from docker container)

 需要编写一个在dock-a中安装docker的Dockerfile。 因为container-a需要执行docker命令到container-b，它与container-a一起运行。 我的理解是你在编写Dockerfile时不应该使用“sudo”。 但我陷入困境 - 我指派给docker组的用户是什么？ 当您运行docker exec -it ，您将自动为root。 
 
 sudo usermod -a -G docker whatuser? 
 
 另外（我在集装箱内手动尝试这个 - 看它是否有效）你必须做一个newgrp docker来激活对组的更改。 我这样做的任何时候，当我没有sudo'ed时，我最终sudo'ing。 那有意义吗？ 症状是 - 我去exit容器，我必须退出两次（好像我改变了用户）。 
 
 我究竟做错了什么？ 

Need to write a Dockerfile that installs docker in container-a. Because container-a needs to execute a docker command to container-b that's running alongside container-a. My understanding is you're not supposed to use "sudo" when writing the Dockerfile. But I'm getting stuck -- what user to I assign to docker group? When you run docker exec -it, you are automatically root.
 
sudo usermod -a -G docker whatuser?
 
Also (and I'm trying this out manually inside container-a to see if it even works) you have to do a newgrp docker to activate the changes to groups. Anytime I do that, I end up sudo'ing when I haven't sudo'ed. Does that make sense? The symptom is -- I go to exit the container, and I have to exit twice (as if I changed users).
 
What am I doing wrong?

原文：https://stackoverflow.com/questions/42237352