Docker容器未启动，显示为“ n秒钟前退出” [英] Docker container doesn't start, showing as 'Exited n seconds ago'
问题描述
我试图了解docker在启动/进入容器时的工作方式。我对此很陌生，请耐心等待。我尝试在SO中找到我需要的答案，但到目前为止还没有找到。
I am trying to understand how docker works when it comes to starting / getting into a container. I am new to this so bear with me. I tried finding the answer to my need in SO but could not so far.
我正在尝试实现3个基本目标：
I am trying to achieve 3 basic things:
- 启动容器
- 确保所有端口都映射到我的容器（即，我可以从容器外部看到我的容器的apache）
- SSH或将控制台插入我的容器
这是我用来启动容器的内容：
Here is what I am using to start a container:
caldav@caldav:~/docker/caldav-server$ sudo docker run -it -d -P caldav-server service apache2 start
48fbea1865e302768a863767bf01b08f35f0221a4b29e5f2208d57e54660ef42
48fbea1865e302768a863767bf01b08f35f0221a4b29e5f2208d57e54660ef42
但是当我运行ps时，我将其视为 n秒前退出：
But when I run ps, I see it as 'exited n seconds ago':
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
48fbea1865e3 caldav-server "service apache2 sta 2 seconds ago Exited (0) 1 seconds ago
这甚至意味着什么？显然，当我进入 http：// [IP_ADDRESS]
What does this even mean? And obviously, I dont get to see it up and running when I go to http://[IP_ADDRESS]
更新：好的，当我删除apache start命令时，它似乎仍然存在：
UPDATE: Ok, when I remove the apache start command it seems to stay up:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
20d5daca6237 caldav-server "/bin/bash" 10 seconds ago Up 9 seconds thirsty_ritchie
但是后来我似乎无法将控制台加入其中。这是我尝试的方法：
But then I dont seem to be able to get console into it. This is what I tried:
docker attach 20d5daca6237
哪个还可以（允许我使用bash）。但是，当我尝试通过键入退出
Which is fine (gives me bash access). However, when I try to exit it by typing
$ exit
然后将容器显示为ps中的退出状态。我做错了吗？
it then shows the container as the 'exited' status in ps. Am I doing it wrong?
推荐答案
Docker容器仅在其初始命令运行的情况下运行。在这种情况下，该命令是 service apache2 start ，该命令在不超过几秒钟的时间内退出，此时容器也将停止。如果要在容器中运行守护程序，则需要使该守护程序成为主程序并使使其在前台运行，或者使用带有可处理守护程序的命令的映像，例如< a href = https://github.com/phusion/baseimage-docker rel = nofollow> phusion / baseimage 。
A Docker container runs only as long as its initial command does. In this case, that command is service apache2 start, which exits after no more than a couple seconds, at which point the container stops as well. If you want to run a daemon in a container, you need to either make the daemon the primary program and make it run in the foreground or else use an image with a command that can handle daemons, like phusion/baseimage.
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