I am trying to create my own docker container, and custom service which I created for my work, this is my service file
[1/1] /etc/systemd/system/qsinavAI.service
[Unit]
Description=uWSGI instance to serve Qsinav AI
After=network.target
[Service]
User=www-data
Group=www-data
WorkingDirectory=/root/AI/
Environment="PATH=/root/AI/bin"
ExecStart=/root/AI/bin/uwsgi --ini ai.ini
[Install]
WantedBy=multi-user.target
and when I am trying to run this service I get this error
System has not been booted with systemd as init system (PID 1). Can't
operate. Failed to connect to bus: Host is down
I searched a lot to find a solution but I could not, how can I enable the systemctl in docker.
this is the command that I am using to run the container
docker run -dt -p 5000:5000 --name AIPython2 --privileged -v /sys/fs/cgroup:/sys/fs/cgroup:ro --cap-add SYS_ADMIN last_python_image
If your application is only ever run inside a container then you should create a docker-entrypoint.sh script with an "exec" at the end so that your application is run as a remapped PID 1 in the container. That way cloud systems can see if the application is alive and they can send a SIGTERM to stop the application.
#! /bin/bash
cd /root/AI
PATH=/root/AI/bin
exec /root/AI/bin/uwsgi --ini ai.ini
If your application shall be able to run in systemd environment outside of a container then you can choose to reuse the systemd descriptor. It requires an init-daemon on PID 1 and a service manager to check the "enbabled" services. One example would be the systemctl-docker-replacement script.
Docker containers should have an "entrypoint" command that runs in foreground to keep the container running. The basic idea behind a container is that it runs as long as the root process that started it, keeps running. Since you will issue a systemctl start qsinavAI.service, the command will succeed but once this command exits, the container will stop.
By design, containers started in detached mode exit when the root process used to run the container exits, ...
See some reference about this and starting nginx service in the official documentation.
So instead of trying to run your application as a service, you should have an entrypoint statement at the end of your Dockerfile. Then when you start this container with docker run, you can specify -d to run it in "detached" mode.
Example, taking the command from ExecStart and assuming it runs in foreground:
ENTRYPOINT ["/root/AI/bin/uwsgi", "--ini", "ai.ini"]
Exemple how to create image with systemd and boot like a real environment. A Dockerfile is required.
FROM ubuntu:22.04
RUN echo 'root:root' | chpasswd
RUN printf '#!/bin/sh\nexit 0' > /usr/sbin/policy-rc.d
RUN apt-get update
RUN apt-get install -y systemd systemd-sysv dbus dbus-user-session
ENTRYPOINT ["/sbin/init"]
/sbin/init is important to init systemd and enable systemctl.
Then build the system.
docker build -t testimage -f Dockerfile .
docker run -it --privileged --cap-add=ALL testimage
Without making the title too long, here is the scenario...
I have two scripts:
The first script (host_startup.sh) checks whether a website is up. When it finally posts, then it opens the website in the default browser:
URL=http://localhost:9876
until contents=$(wget -q --spider --no-check-certificate "$URL")
do
sleep 1
done
xdg-open ${URL} &
The second script (run.sh) starts the host_startup script and then starts up a Docker container which serves up a webpage at the aforementioned address:
(../../host_startup.sh) &
docker run --rm -it \
-p 9786:9786 \
company:image
Note that the docker command runs with the --rm flag. However, when I run the run.sh script, and Ctrl+C the process, the Docker image is still running... Specifically, docker ps shows the container still.
I would like Ctrl+C to stop the container and clean it up.
I thought that the container would stop and cleanup because I put the host_startup.sh script in the background, NOT the docker run command...
Please tell me how I can achieve the desired behavior.
Appearantly "Bash does not forward signals like SIGTERM to processes it is currently waiting on".
So you could modify your run.sh to:
(../../host_startup.sh) &
exec docker run --rm -it \
-p 9786:9786 \
company:image
Which would replace the fork of the shell with the docker process instad of waiting for it.
Based on Suart P. Bentley's answer on the unix stackexchange
Alternatively you could manually listen to and act on signals using a modified version of cuonglm's answer to the same question.
I end my Debian Dockerfile with these lines:
EXPOSE 80 22
COPY etc/supervisor/conf.d /etc/supervisor/conf.d
CMD ["/usr/bin/supervisord", "-c", "/etc/supervisor/supervisord.conf"]
In /etc/supervisor/conf.d/start.conf file:
[program:ssh]
command=/usr/sbin/service ssh restart
[program:nginx]
command=/usr/sbin/nginx -g 'daemon off;'
[program:systemctl]
command=/bin/systemctl daemon-reload
[program:systemctl]
command=/bin/systemctl start php7-fpm.service
If I try to run this Docker image with the following command:
$ docker run -d -p 8080:80 -p 8081:22 lanti/debian
It's immediately stops running. if I try to run it on the foreground:
$ docker run -it -v /home/core/share:/root/share -p 8080:80 -p 8081:22 lanti/debian
It's the same, immediate exit. If I run with bash CMD:
$ docker run --rm -it -v /home/core/share:/root/share -p 8080:80 -p 8081:22 lanti/debian bash
It stays active in the console, but the predefined commands by supervisor not run, so I need to run $ service supervisor restart inside the container, otherwise Nginx and SSH won't be started.
How I can start a docker container with multiple commands run at startup? In the past I used ExecStartPost lines in a systemd file under the host OS, but becouse of that, the systemd file became complex so I try to move the pre-start commands into the container, to run automatically at any type of startup.
This docker container will have nginx, php, ssh, phpmyadmin and mysql in the future. I don't want multiple containers.
Thank You for your help!
Lets preface this by saying running the kitchen sink in a docker container is not a best practice. Docker is not a virtual machine.
That said, a few problems.
just like the processes that supervisor controls, supervisor itself should NOT daemonize. Add -n
I'm not entirely sure why you expect, need, or want to have systemd and supervisor running. Most docker containers do not have a functioning init system. Why not just user supervisor for everything? Unless docker has significantly changed in the last couple versions, systemd inside the container will not work like you think it should.
According to tutorial I read so far, use "docker run -d" will start a container from image, and the container will run in background. This is how it looks like, we can see we already have container id.
root#docker:/home/root# docker run -d centos
605e3928cdddb844526bab691af51d0c9262e0a1fc3d41de3f59be1a58e1bd1d
But if I ran "docker ps", nothing was returned.
So I tried "docker ps -a", I can see container already exited:
root#docker:/home/root# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
605e3928cddd centos:latest "/bin/bash" 31 minutes ago Exited (0) 31 minutes ago kickass_swartz
Anything I did wrong? How can I troubleshoot this issue?
The centos dockerfile has a default command bash.
That means, when run in background (-d), the shell exits immediately.
Update 2017
More recent versions of docker authorize to run a container both in detached mode and in foreground mode (-t, -i or -it)
In that case, you don't need any additional command and this is enough:
docker run -t -d centos
The bash will wait in the background.
That was initially reported in kalyani-chaudhari's answer and detailed in jersey bean's answer.
vonc#voncvb:~$ d ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4a50fd9e9189 centos "/bin/bash" 8 seconds ago Up 2 seconds wonderful_wright
Note that for alpine, Marinos An reports in the comments:
docker run -t -d alpine/git does not keep the process up.
Had to do: docker run --entrypoint "/bin/sh" -it alpine/git
Original answer (2015)
As mentioned in this article:
Instead of running with docker run -i -t image your-command, using -d is recommended because you can run your container with just one command and you don’t need to detach terminal of container by hitting Ctrl + P + Q.
However, there is a problem with -d option. Your container immediately stops unless the commands keep running in foreground.
Docker requires your command to keep running in the foreground. Otherwise, it thinks that your applications stops and shutdown the container.
The problem is that some application does not run in the foreground. How can we make it easier?
In this situation, you can add tail -f /dev/null to your command.
By doing this, even if your main command runs in the background, your container doesn’t stop because tail is keep running in the foreground.
So this would work:
docker run -d centos tail -f /dev/null
Or in Dockerfile:
ENTRYPOINT ["tail"]
CMD ["-f","/dev/null"]
A docker ps would show the centos container still running.
From there, you can attach to it or detach from it (or docker exec some commands).
According to this answer, adding the -t flag will prevent the container from exiting when running in the background. You can then use docker exec -i -t <image> /bin/bash to get into a shell prompt.
docker run -t -d <image> <command>
It seems that the -t option isn't documented very well, though the help says that it "allocates a pseudo-TTY."
Background
A Docker container runs a process (the "command" or "entrypoint") that keeps it alive. The container will continue to run as long as the command continues to run.
In your case, the command (/bin/bash, by default, on centos:latest) is exiting immediately (as bash does when it's not connected to a terminal and has nothing to run).
Normally, when you run a container in daemon mode (with -d), the container is running some sort of daemon process (like httpd). In this case, as long as the httpd daemon is running, the container will remain alive.
What you appear to be trying to do is to keep the container alive without a daemon process running inside the container. This is somewhat strange (because the container isn't doing anything useful until you interact with it, perhaps with docker exec), but there are certain cases where it might make sense to do something like this.
(Did you mean to get to a bash prompt inside the container? That's easy! docker run -it centos:latest)
Solution
A simple way to keep a container alive in daemon mode indefinitely is to run sleep infinity as the container's command. This does not rely doing strange things like allocating a TTY in daemon mode. Although it does rely on doing strange things like using sleep as your primary command.
$ docker run -d centos:latest sleep infinity
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
d651c7a9e0ad centos:latest "sleep infinity" 2 seconds ago Up 2 seconds nervous_visvesvaraya
Alternative Solution
As indicated by cjsimon, the -t option allocates a "pseudo-tty". This tricks bash into continuing to run indefinitely because it thinks it is connected to an interactive TTY (even though you have no way to interact with that particular TTY if you don't pass -i). Anyway, this should do the trick too:
$ docker run -t -d centos:latest
Not 100% sure whether -t will produce other weird interactions; maybe leave a comment below if it does.
Hi this issue is because docker containers exit if there is no running application in the container.
-d
option is just to run a container in deamon mode.
So the trick to make your container continuously running is point to a shell file in docker which will keep your application running.You can try with a start.sh file
Eg: docker run -d centos sh /yourlocation/start.sh
This start.sh should point to a never ending application.
In case if you dont want any application to be running,you can install monit which will keep your docker container running.
Please let us know if these two cases worked for you to keep your container running.
All the best
You can accomplish what you want with either:
docker run -t -d <image-name>
or
docker run -i -d <image-name>
or
docker run -it -d <image-name>
The command parameter as suggested by other answers (i.e. tail -f /dev/null) is completely optional, and is NOT required to get your container to stay running in the background.
Also note the Docker documentation suggests that combining -i and -t options will cause it to behave like a shell.
See:
https://docs.docker.com/engine/reference/run/#foreground
I have this code snippet run from the ENTRYPOINT in my docker file:
while true
do
echo "Press [CTRL+C] to stop.."
sleep 1
done
Run the built docker image as:
docker run -td <image name>
Log in to the container shell:
docker exec -it <container id> /bin/bash
execute command as follows :
docker run -t -d <image-name>
if you want to specify port then command as below:
docker run -t -d -p <port-no> <image-name>
verify the running container using following command:
docker ps
Docker container exits if task inside is done, so if you want to keep it alive even if it does not have any job or already finished them, you can do docker run -di image. After you do docker container ls you will see it running.
Docker requires your command to keep running in the foreground. Otherwise, it thinks that your applications stops and shutdown the container.
So if your docker entry script is a background process like following:
/usr/local/bin/confd -interval=30 -backend etcd -node $CONFIG_CENTER &
The '&' makes the container stop and exit if there are no other foreground process triggered later.
So the solution is just remove the '&' or have another foreground CMD running after it, such as
tail -f server.log
If you are using CMD at the end of your Dockerfile, what you can do is adding the code at the end. This will only work if your docker is built on ubuntu, or any OS that can use bash.
&& /bin/bash
Briefly the end of your Dockerfile will look like something like this.
...
CMD ls && ... && /bin/bash
So if you have anything running automatically after you run your docker image, and when the task is complete the bash terminal will be active inside your docker. Thereby, you can enter you shell commands.
Maybe it is just me but on CentOS 7.3.1611 and Docker 1.12.6 but I ended up having to use a combination of the answers posted by #VonC & #Christopher Simon to get this working reliably. Nothing I did before this would stop the container from exiting after it ran CMD successfully. I am starting oracle-xe-11Gr2 and sshd.
Dockerfile
...
RUN ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key -N '' && systemctl enable sshd
...
CMD /etc/init.d/oracle-xe start && /sbin/sshd && tail -f /dev/null
Then adding -d -t and -i to run
docker run --shm-size=2g --name oracle-db -d -t -i -p 5022:22 -p 5080:8080 -p 1521:1521 centos-oracle:7.3.1611
Finally after hours of bashing my head against the wall
ssh -v root#127.0.0.1 -p 5022
...
root#127.0.0.1's password:
debug1: Authentication succeeded (password).
For whatever reason the above will exit after executing CMD if the tail -f is removed, or any of the -t -d -i options are omitted.
I had the same issue, just opening another terminal with a bash on it worked for me :
create container:
docker run -d mcr.microsoft.com/mssql/server:2019-CTP3.0-ubuntu
containerid=52bbc9b30557
start container:
docker start 52bbc9b30557
start bash to keep container running:
docker exec -it 52bbc9b30557 bash
start process you need:
docker exec -it 52bbc9b30557 /path_to_cool_your_app
Running docker with interactive mode might solve the issue.
Here is the example for running image with and without interactive mode
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker run -d -t -i test_again1.0
b6b9a942a79b1243bada59db19c7999cfff52d0a8744542fa843c95354966a18
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker run -d -t -i test_again1.0 bash
c3d6a9529fd70c5b2dc2d7e90fe662d19c6dad8549e9c812fb2b7ce2105d7ff5
chaitra#RSK-IND-BLR-L06:~/dockers$ sudo docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
c3d6a9529fd7 test_again1.0 "bash" 2 seconds ago Up 1 second awesome_haibt
You can simply use:
docker container run -d -it <container name or id> /bin/bash
I have explained it in the following post that has the same question.
How to retain docker alpine container after "exit" is used?
I was also facing the same problem but in a different manner. When I create the docker containers. it automatically stops the unused containers which are just running in the background. Sometimes it also stops the containers that are in the use.
In my situation, this is because of the permission of the docker.sock files it earlier has.
what you have to do is :-
Install docker again.(As i work on ubuntu i install it from here)
Run the command to change the permissions.
sudo chmod 666 /var/run/docker.sock
Install docker-compose (this is optional as I have compose file to create many containers together)
sudo curl -L "https://github.com/docker/compose/releases/download/1.26.0/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
sudo chmod +x /usr/local/bin/docker-compose
check for the version to ensure that I have the latest one and not get problem with some deprications.
Then I run the docker container build.
Argument order matters
Jersey Beans answer (all 3 examples) worked for me. After quite a bit of trial and error I realized that the order of the arguments matter.
Keeps the container running in the background:
docker run -t -d <image-name>
Keeps the container running in the foreground: docker run <image-name> -t -d
It wasn't obvious to me coming from a Powershell background.
if you want to operate on the container, you need to run it in foreground to keep it alive.
There are multiple options out there to run the container in foreground/detached state. But if you still feel the issue is not resolved, you can try troubleshooting the issue by viewing the logs.
sudo docker logs -f >> container.log
additionally you can also use --details to show extra details provided to logs.
Incorrect Path to App in Dockerfile:
I was migrating an application from a RHEL server to a Docker container using Alpine Linux.
No errors during the build, so I was surprised to see the container immediately exit!
First port of call:
docker logs <containerID>
This revealed the path of the binary I had supplied to CMD in the Dockerfile was bogus:
line 0: /sbin/postfix: not found
Well that told me how things were broken, but not specifically where: I still required the correct path for the binary in Alpine Linux...
Troubleshooting:
Googling didn't reveal the correct path to it, so I added the following line to my Dockerfile:
RUN which postfix
I then reviewed my build logging- provided by the below command appended to my build command- to retrieve the value of RUN which postfix
--progress=plain > /path/to/build.log 2>&1
The Fix:
I deleted this test build, supplied the correct path- /usr/sbin/postfix - to CMD in the Dockerfile, deleted RUN which postfix and ran another build.
Voila; the process now remained up.
So a duff path was causing the container to immediately exit...
These 4 commands all work to keep your docker container running:
docker run -td centos
docker run -dt centos
docker run -t -d centos
docker run -d -t centos
Firstly, You need to check if any container is running
Type command,
docker ps -all
If any container is running then stop them
Type command,
docker stop Container Id
Now, Finally run the docker by using below command..........
docker run -t -p 2020:3000 dockerImageName
Hence, Open your google chrome and visit on localhost:2020
Congrats :)
Ok, I have exhausted pretty much all threads and articles, but still cant get my apache webserver to run in standalone mode on Centos Docker Container.
Here is my simplified Dockerfile
# install apache
RUN yum -y install httpd
# start the webserver
ADD startservice /startservice
RUN chmod 775 /startservice
EXPOSE 80
CMD ["/startservice"]
My starservice script just has
#!/usr/bin/sh
service httpd start
I can build fine, but, cant seem to run the container in daemon/standalone mode. How do I do that?
I am using this to run the container in standalone mode
docker run -p 80:80 -d -t webserver
I have to log onto the container and start the service for the webserver to run.
docker run -p 80:80 -i -t webserver bash
service httpd start
This is a classic docker issue. The process you start must execute in the foreground, otherwise the container simply stops.
So, to be able to do so the following can be used in your startservice script:
#!/usr/bin/sh
service httpd start
# Tail the log file
tail -f /var/log/httpd/access_log
# Alternatively, you can tail any file or even /dev/null
#tail -f /dev/null
Note that there are also other ways of fixing this. One way is to use supervisord that keeps your processes alive. The supervisord-approach is cleaner and les hackish than the tail -f-approach and I would personally prefer that alternative.
Another alternative is simply that you do not start httpd as a service but instead provide the -DFOREGROUND parameter. This will make httpd be attached to the shell (and not fork off to a background process).
/usr/sbin/httpd -DFOREGROUND
For more info on http in foreground mode, check this question.