How to fix ctrl+c inside a docker container

问题

If I connect to a docker container

$> docker exec -it my_container zsh

and inside it I want to kill something I started with ctrl+c I noticed that it takes forever to complete. I've googled around and it seems that ctrl+c works a bit different than you would expect. My question, how can I fix ctrl+c inside a container ?

回答1:

The problem is that Ctrl-C sends a signal to the top-level process inside the container, but that process doesn't necessarily react as you would expect. The top-level process has ID 1 inside the container, which means that it doesn't get the default signal handlers that processes usually have. If the top-level process is a shell, then it can receive the signal through its own handler, but doesn't forward it to the command that is executed within the shell. Details are explained here. In both cases, the docker container acts as if it simply ignores Ctrl-C.

Starting with docker 0.6.5, you can add -t to the docker run command, which will attach a pseudo-TTY. Then you can type Control-C to detach from the container without terminating it.

If you use -t and -i then Control-C will terminate the container. When using -i with -t then you have to use Control-P Control-Q to detach without terminating.

Test 1:

$ ID=$(sudo docker run -t -d ubuntu /usr/bin/top -b)
$ sudo docker attach $ID
Control-P Control-Q
$ sudo docker ps

The container is still listed.

Test 2:

$ ID=$(sudo docker run -t -i -d ubuntu /usr/bin/top -b)
$ sudo docker attach $ID
Control-C
$ sudo docker ps

the container is not there (it has been terminated). If you type Control-P Control-Q instead of Control-C in the 2nd example, the container would still be running.

Wrap the program with a docker-entrypoint.sh bash script that blocks the container process and is able to catch ctrl-c. This bash example might help: https://rimuhosting.com/knowledgebase/linux/misc/trapping-ctrl-c-in-bash

#!/bin/bash

# trap ctrl-c and call ctrl_c()
trap ctrl_c INT

function ctrl_c() {
        echo "** Trapped CTRL-C"
}

for i in `seq 1 5`; do
    sleep 1
    echo -n "."
done

回答2:

Use Ctrl+\ instead of Ctrl+C
it kills the process instead of politely asking it to shut down.(read more here.)

回答3:

I had the similar problem when I was trying to run mdbook (the Rust executable) in the docker container. The mdbook starts simple webserver and I want to stop it via Ctrl+C which did not work.

$ docker -ti --rm -p 4321:4321 my-docker-image mdbook serve --hostname 0.0.0.0 --port 4321
2019-08-16 14:00:11 [INFO] (mdbook::book): Book building has started
2019-08-16 14:00:11 [INFO] (mdbook::book): Running the html backend
2019-08-16 14:00:11 [INFO] (mdbook::cmd::serve): Serving on: http://0.0.0.0:4321
2019-08-16 14:00:11 [INFO] (ws): Listening for new connections on 0.0.0.0:3001.
2019-08-16 14:00:11 [INFO] (mdbook::cmd::watch): Listening for changes...
^C^C

Be inspired by @NID's answer I encapsulated the mdbook executable by universal bash script docker-entrypoint.sh which did the trick (without the need to explicitly catch the INT signal).

$ docker -ti --rm -p 4321:4321 my-docker-image docker-entrypoint.sh mdbook serve --hostname 0.0.0.0 --port 4321
2019-08-16 14:00:11 [INFO] (mdbook::book): Book building has started
2019-08-16 14:00:11 [INFO] (mdbook::book): Running the html backend
2019-08-16 14:00:11 [INFO] (mdbook::cmd::serve): Serving on: http://0.0.0.0:4321
2019-08-16 14:00:11 [INFO] (ws): Listening for new connections on 0.0.0.0:3001.
2019-08-16 14:00:11 [INFO] (mdbook::cmd::watch): Listening for changes...
^C $

The content of the docker-entrypoint.sh is very simple:

#!/bin/bash

$@

回答4:

Wasted about 2 hours.

New commands -- (Working fine)

sudo docker stop 
sudo docker rm   
sudo docker run -t

Old commands -- (Not working anymore)

sudo docker stop
sudo docker rm   
sudo docker run
Ctrl + C
sudo docker start

Hope that helps someone.

来源：https://stackoverflow.com/questions/41097652/how-to-fix-ctrlc-inside-a-docker-container