I have a simple dokku app using herokuish buildpack-php with a procfile: web: vendor/bin/heroku-php-apache2 public/
If I try to enter the app with dokku enter <appname> nothing happens, and I am simply returned to my host shell.
I can run dokku run <appname> bash and get a shell, but is, as far as I understand from the documentation placing me in a new container and not in the existing/running one I need access to:
The run command can be used to run a one-off process for a specific command. This will start a new container and run the desired command within that container.
How can I fix this so I can enter my running container?
If you are in the local directory for your app, doing the following will take you into the running container for it:
dokku enter web.1
I've done this a few times today!
As a workaround, you can enter your container using docker. For doing so, run docker ps and note the container ID. Afterwards, run docker exec -it container_id /bin/bash.
I need nginx-openresty and redis in single docker container. I have written docker file its working fine. But thing i need to start my redis service after login into the docker bash to automate this I have written .sh file which contains instrutions like start and stop of redis server and nginx. ENTRYPOINT ["./startup.sh"]
and .sh file is
cd /etc/redis-installation/utils
echo -n | ./install_server.sh
service redis_6379 stop
cd /
cp ./dump.rdb /var/lib/redis/6379/
service redis_6379 start
openresty
My problem is that docker container start and exist when shell execution completed. How can stay the container keep running with nginx and redis in running state.
Try using docker-compose with a link between your app container and your redis container. I suggest using the official redis container
I am developing a web application which depends on a moodle system, as it uses moodles webservices. For my automated tests, I wanted to use docker to provide a preconfigured moodle-application on all my machines. Therefore I created a docker image, which I import from a .tar.gz file.
However, creating a new container-instance from this image behaves inconsistently. Sometimes the container boots up correctly and everything works fine. However, sometimes the container starts but the moodle-website is not reachable. If I connect my bash to the container using docker exec -it <container> bash I see that apache is running. The error logs do not show any entries which might be related to this issue.
If I kill the container instance and boot it up again, everything works as expected (sometimes this step has to be repeated multiple times). Do you have any idea what could be the reason for this strange behaviour? Anyone experiencing similar issues?
Docker is running on Ubuntu 14:04. The problem appears on several machines. The script which imports the image and starts the container looks like this:
#!/usr/bin/env bash
docker rm -f moodle
docker load < my-moodle.tar.gz
docker run -d -p 8080:80 -p 8443:443 -p 3306:3306 --name moodle moodle-image
Thanks in advance!
Successful container startup depends on your container entrypoint and external resources (if the entrypoint has external dependencies). What is the entrypoint? Does it depend on external resources?
We are running a Jenkins CI server from a docker container, started with docker-compose. The Jenkins server is running some jobs which are pulling projects from git and building docker containers the standard way executing docker build . on them. To be able to use docker inside the docker container we are mounting over /var/run/docker.sock with docker-compose to the Jenkins container.
Some of the Dockerfile-s we are trying to build there are downloading files from our fileserver (3rd party installation images for example). Such a Dockerfile command looks like RUN curl -o xx.zip http://fileserver/xx-1.2.3.zip.
The fileserver hostname gets resolved through the /etc/hosts file and it resolves to the host's public IP which runs the Jenkins CI server. The docker-compose config for the Jenkins container also includes the extra_hosts parameter pointing the fileserver to the host's public IP.
The problem is that building the docker container with Jenkins running in it's own container fails with a plain Unknown host: fileserver message. If I enter the Jenkins container via docker exec -it <id>, I can execute the same curl command and it resolves the host, but if I try to run docker build . there which tries to run the same curl command, it fails to resolve the host.
Our host is an RHEL and I failed to reproduce the problem on my desktop Arch Linux so I suspect it's something redhat-specific issue (again).
Add --network=host, so that the build env will use the host machine domain resolution.
docker build --network=host foo/bar:latest .
Docker builds don't happen on the machine issuing the command (your jenkins container, in this case) - they happen on the machine with the Docker Engine. This means that your Jenkins machine tars up the source directory and ships it back to the parent machine for the build to happen. So, check if the curl command works from the parent machine, not the Jenkins container.
I have tried following some tutorials and documentation on dockerizing my web server, but I am having trouble getting the service to run via the docker run command.
This is my Dockerfile:
FROM ubuntu:trusty
#Update and install stuff
RUN apt-get update
RUN apt-get install -y python-software-properties aptitude screen htop nano nmap nginx
#Add files
ADD src/main/resources/ /usr/share/nginx/html
EXPOSE 80
CMD service nginx start
I create my image:
docker build -t myImage .
And when I run it:
docker run -p 81:80 myImage
it seems to just stop:
docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
90e54a254efa pms-gui:latest /bin/sh -c service n 3 seconds ago Exit 0 prickly_bohr
I would expect this to be running with port 81->80 but it is not. Running
docker start 90e
does not seem to do anything.
I also tried entering it directly
docker run -t -i -p 81:80 myImage /bin/bash
and from here I can start the service
service nginx start
and from another tab I can see it is working as intended (also in my browser):
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
408237a5e10b myImage:latest /bin/bash 12 seconds ago Up 11 seconds 0.0.0.0:81->80/tcp mad_turing
So I assume it is something I am doing wrong with my Dockerfile? Could anyone help me out with this, I am quite new to Docker. Thank you!
SOLUTION: Based on the answer from Ivant I found another way to start nginx in the foreground. My Dockerfile CMD now looks like:
CMD /usr/sbin/nginx -g "daemon off;"
As of now, the official nginx image uses this to run nginx (see the Dockerfile):
CMD ["nginx", "-g", "daemon off;"]
In my case, this was enough to get it to start properly. There are tutorials online suggesting more awkward ways of accomplishing this but the above seems quite clean.
Docker container runs as long as the command you specify with CMD, ENTRTYPOINT or through the command line is running. In your case the service command finishes right away and the whole container is shut down.
One way to fix this is to start nginx directly from the command line (make sure you don't run it as a daemon).
Another option is to create a small script which starts the service and then sleeps forever. Something like:
#!/bin/bash
service nginx start
while true; do sleep 1d; done
and run this instead of directly running the service command.
A third option would be to use something like runit or similar program, instead of the normal service.
Using docker-compose:
To follow the recommended solution, add to docker-compose.yml:
command: nginx -g "daemon off"
I also found I could simply add to nginx.conf:
daemon off;
...and continue to use in docker-compose.yml:
command: service nginx start
...although it would make the config file less portable outside docker.
Docker as a very nice index of offical and user images. When you want to do something, chances are someone already did it ;)
Just search for 'nginx' on index.docker.io, you will see, there is an official nginx image: https://registry.hub.docker.com/_/nginx/
There you have a full guide to help you start your webserver.
Feel free to take a look at other users nginx image to see variants :)
The idea is to start nginx in foreground mode.
If you run "service nginx start", it is a parent process which will start a child process of nginx. If you run "service nginx start" as CMD in a container, the Process ID 1 for the container will be "service nginx start" or ServiceManager (SystemD), while actual nginx would be running as a child process.
If you run "service nginx start", and then "ps -ef", you will get output as below. I have run it my host OS.
root#ip-172-31-85-74:/home/ubuntu# service nginx start
root#ip-172-31-85-74:/home/ubuntu#
root#ip-172-31-85-74:/home/ubuntu# ps -ef | grep nginx
root 18593 1 0 12:27 ? 00:00:00 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
www-data 18595 18593 0 12:27 ? 00:00:00 nginx: worker process
root 18599 17918 0 12:27 pts/0 00:00:00 grep --color=auto nginx
So, here the process ID 18593 is the child process which has parent process 1.
Container exits when their Process ID 1 exits. And in case of CMD "service nginx start", the PID 1 is the process manager, may be SystemD. It starts nginx as a child process, and exits itself, hence the container exits.
Similarly, if you run a shell script (for eg : start.sh) in CMD, as soon as the script ends, the container will exit. Even though the script starts some services (eg - nginx) in its execution, as soon as the script ends, the container will exit, because the PID 1 will be of the shell script. The parent process will be "./start.sh", and the services started by script will be child processes. In case you want to use a shell script in CMD, and want the container to run indefinitely, you need a command at last of the script which doesn't let it end. Something as shown below:
#!/bin/bash
service nginx start
while true; do sleep 1d; done