i am trying write a Dockerfile like that
FROM debian:stable
RUN apt-get update
RUN apt-get install -y mariadb-server
EXPOSE 3306
CMD ["mysqld"]
I create the image with
docker build -t debian1 .
And i create the container with
docker run -d --name my_container_debian -i -t debian1
20 seconds after, docker ps -a tells that container is exited. Why? I want the container is up and mariadb running. Thanks. Sorry for the question.
mysqld alone would exit too soon.
If you look at a MySQL server Dockerfile, you will note its ENTRYPOINT is a script docker-entrypoint.sh which will exec mysqld in foreground.
exec "$#"
Related
I'm new to docker.
I'm setting up nginx server to serve static files inside a docker container. I'd like to enable nginx to start automatically on every startup inside a docker container.
I've tried changing ENTRYPOINT, CMD and crontab when building DockerImage. But these settings to run nginx on every startup works only the first time I "run" a container. When I "stop" the container and "start" it again, nginx does not start automatically inside the container.
I'm looking for a way to start nginx on every startup of a container and my first question is "is it possible to do this?"
My second question is about a container cycle. Given that there are not many discussions on this subject (all discussions are about automatically running a script or sth else at the moment of "run"), I wonder if it is more efficient to "run" and "kill" a container each time than just "stopping" and "starting" a container.
Here are the lines of code I tried for DockerImage (with crontab), which was my first try.
RUN apt-get install -y cron
COPY run_server /etc/cron.d/run_server
RUN chmod 0644 /etc/cron.d/run_server
RUN crontab /etc/cron.d/run_server
RUN touch /var/log/cron.log
CMD cron && tail -f /var/log/cron.log
run_server is a simple crontab config file which includes:
#reboot service nginx start
Since this was not the solution I was looking for (it worked only when I "ran" a conainer, not "stopped" and "started" a container) I tried with supervisor, too.
RUN apt-get -y install supervisor && \
mkdir -p /var/log/supervisor && \
mkdir -p /etc/supervisor/conf.d
ADD supervisor.conf /etc/supervisor.conf
CMD ["supervisord", "-c", "/etc/supervisor.conf"]
supervisor.confg contains:
[supervisord]
nodaemon=true
[program:run_server]
command=/usr/bin/python3.6 /home/server.py
autostart=true
directory=/home
redirect_stderr=true
But neither of them worked the way I wanted ..
my Dockerfile , container ( CentOS 8 and nginx ) linux mint 19.3 Docker version 19.03.4
# howto: Dockerfile
# CentOS 8 and nginx
# docker build -t centose .
# docker run -it -p 80:80 centose
# curl localhost
FROM centos:latest
# MAINTAINER їван
RUN yum -y install nginx
EXPOSE 80
CMD ["/usr/sbin/nginx", "-g", "daemon off;"]
#WORKDIR /usr/sbin/
I would try to update my docker file and enable the nginx service so it will be started during the next reboot.
Here is a couple of different ways:
RUN systemctl enable nginx
RUN service nginx start
Another way would be to add a bootstrap script that starts the service:
#!/bin/bash
sudo service nginx start
tail -f /var/log/nginx/error.log
Make sure the bootstrap.sh is executable i.e sudo chmod +x bootstrap.sh.
Then update your docker file:
COPY boostrap.sh /bin/.
CMD ["bootstrap.sh"]
you can apply that using docker restart policy
you can simply set it when creating the container or updating the created ones
examples: docker run -t -d --restart unless-stopped nginx
to update the created ones: docker update --restart unless-stopped {container ID}
Please help. When I want to go into a container is says
Error response from daemon: Container 90599013c666d332ff6560ccde5053d9127e72042ecc3887550aef90fa1d1eac is not running
My DockerFile:
FROM ubuntu:16.04
MAINTAINER Anton Lapitski <a.lapitski#godeltech.com>
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
ADD ./ /usr/src/app
EXPOSE 80
ENTRYPOINT ["/bin/sh", "-c", "/usr/src/app/entry.sh"]
Starting script - start.sh:
sudo docker build -t starter .
sudo docker run -t -v mounted-directory:/usr/src/app/mounted-directory -p 80:80 starter
entry.sh script:
echo "Hello World"
ls -l
pwd
if mountpoint -q /mounted-directory
then
echo "mounted"
else
echo "not mounted"
fi
sudo docker ps -a gives:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
90599013c666 starter "/bin/sh -c /usr/src…" 18 minutes ago Exited (0) 18 minutes ago thirsty_wiles
And mosе important:
sudo docker exec -it 90599013c666 bash
Error response from daemon: Container 90599013c666d332ff6560ccde5053d9127e72042ecc3887550aef90fa1d1eac is not running
Please could you tell what I am doing wrong?
P.S adding -d flag when running not helped.
Once the ENTRYPOINT completes (in any form), the container exits.
Once the container exits, you can't docker exec into it.
If you want to get a shell on the image you just built to poke around in it, you can
sudo docker run --rm -it --entrypoint /bin/sh starter
To make this slightly easier to run, you might change ENTRYPOINT to CMD in your Dockerfile. (Docker will run the ENTRYPOINT passing the CMD as command-line arguments; or if there is no entrypoint just run the CMD.)
...
RUN chmod +x ./app.sh
CMD ["./app.sh"]
Having done that, you can more easily override the command
sudo docker run --rm -it starter /bin/sh
You can try
docker start container_id and then docker exec -ti container_id bash for a stopped container.
You cannot execute the container, because your ENTRYPOINT script has been finished, and the container stopped. Try this:
Remove the ENTRYPOINT from your Dockerfile
Rebuild the image
run it with sudo docker run -it -v mounted-directory:/usr/src/app/mounted-directory -p 80:80 starter sh
The key is the i flag and the sh at the end of the command.
I tried these two commands and it works:
sudo docker start <container_id>
docker exec -it <containerName> /bin/bash
I pull & run an image like
docker run -d --name=lemp \
-v /Users/bappa/Desktop/server/www:/var/www/ \
-p 8080:80 \
stenote/docker-lemp:16.04
& then go to bash like
docker exec -it lemp bash
which is absolutely fine. But When I do with ubuntu:16.04 image same thing. I found response like below
Where is the problem? why the container exit? Thanks.
The reason that caused the different behavior is because of their Dockerfile CMD or ENTRYPOINT.
Once the main process (CMD or ENTRYPOINT) finishes, a docker container stops.
If you look at docker-lemp Dockerfile:
ENTRYPOINT ["/entrypoint.sh"]
Comparing to Ubuntu Dockerfile:
CMD ["bash"]
docker-lemp runs entrypoint.sh which runs further processes that remain in the foreground while Ubuntu runs bash that quits itself after completion.
If you want to keep Ubuntu in the background, a simple trick would be:
docker container run -d ubuntu:16.04 tail -f /dev/null
This replaces the default CMD bash with tail -f /dev/null so the container does not exits.
I am learning docker these days, and starts with building mysql image by myself.
Dockerfile:
FROM centos
MAINTAINER Michael
ENV REFRESHED_AT 2016-07-29
RUN yum install -y mysql mariadb-server
VOLUME /var/lib/mysql
ENTRYPOINT ["/usr/libexec/mysqld", "--user=root"]
EXPOSE 3306
docker run command
docker run -d --name mysql -v /root/docker/mysql/data:/var/lib/mysql -p 3306:3306 michael/mysql
This gave an error because I have to exec mysql_install_db first to init DB. But I could not add RUN mysql_install_db in the Dockerfile since I want to use Volume as external data store.
So how should I do this ?
I know there's an official image named mysql. I just want to do this as practice.
UPDATE:
Thanks to #Pieter . I finally did this by using his solution which is provide another entrypoint.sh combines init & start scripts then make it as ENTRYPOINT in Dockerfile :
FROM centos
MAINTAINER Michael
ENV REFRESHED_AT 2016-07-29
RUN yum install -y mysql mariadb-server
VOLUME /var/lib/mysql
COPY entrypoint.sh /usr/local/bin/
ENTRYPOINT ["entrypoint.sh"]
EXPOSE 3306
entrypoint.sh
#!/bin/bash
if [ ! -d "/var/lib/mysql/mysql" ]; then #check whether the DB is initialized.
echo 'Initializing database'
mysql_install_db
echo 'Database initialized'
fi
/usr/libexec/mysqld --user=root
docker run
docker run -d --name mysql -v /root/docker/mysql/data:/var/lib/mysql -p 3306:3306 michael/mysql
And this gives a generic solution for such scenario.
I'm no expert but for all I know there is no way to run some script before ENTRYPOINT as ENTRYPOINT is literally the first thing your container runs.
What you can do is add a custom script to your docker container that contains both the mysql_install_db and mysqld instructions and use that as the entrypoint.
So your dockerfile might look like this.
FROM centos
MAINTAINER Michael
ENV REFRESHED_AT 2016-07-29
RUN yum install -y mysql mariadb-server
VOLUME /var/lib/mysql
COPY entrypoint.sh /
ENTRYPOINT ["/entrypoint.sh"]
EXPOSE 3306
entrypoint.sh would simply look like this.
/usr/libexec/mysql_install_db --user=root
/usr/libexec/mysqld --user=root
Note that the same technique is also used in the official mariadb docker image. See https://github.com/docker-library/mariadb/tree/d969a465ee48fe10f4b532276f7337ddaaf3fc36/10.1
Note that the official image combines ENTRYPOINT with CMD. As you're learning docker you might want to take a look at https://www.ctl.io/developers/blog/post/dockerfile-entrypoint-vs-cmd/ for more information on how ENTRYPOINT and CMD can be used together.
UPDATE
Assuming that mysql_install_db simply creates some files under /var/lib/mysql you should be able to run mysql_install_db as part of your docker build. (This doesn't mean that you should though -> see official mariadb image).
The docker run command initializes a newly created volume with any data that exists at the specified location within the base image. See https://docs.docker.com/engine/reference/builder/#/volume
I am having a weird problem.
I am not able to ssh to docker container having ip address 172.17.0.61.
I am getting following error:
$ ssh 172.17.0.61
ssh: connect to host 172.17.0.61 port 22: Connection refused
My Dockerfile does contain openssh-server installation step:
RUN apt-get -y install curl runit openssh-server
And also step to start ssh:
RUN service ssh start
What could be the issue?
When I enter into container using nsenter and start ssh service then I am able to ssh. But while creating container ssh-server doesn't seems to start.
What should I do?
When building a Dockerfile you would create an image. But you can't create an image with an already running ssh daemon or any running service else. First if you create a running container out of the image you can start services inside. E.g. by appending the start instruction to the docker run command:
sudo docker run -d mysshserver service ssh start
You can define a default command for your docker image with CMD. Here is an example Dockerfile:
FROM ubuntu:14.04.1
MAINTAINER Thomas Steinbach
EXPOSE 22
RUN apt-get install -y openssh-server
CMD service ssh start && while true; do sleep 3000; done
You can build an run this image with the following two commands:
sudo docker build -t sshtest .
sudo docker run -d -P --name ssht sshtest
Now you can connect to this container via ssh. Note that in the example Dockerfile no user and no login was created. This image is just for example and you can start an ssh connection to it, but not login.
In my opinion there is a better approach:
Dockerfile
FROM ubuntu:14.04.1
EXPOSE 22
COPY docker-entrypoint.sh /docker-entrypoint.sh
RUN chmod +x /docker-entrypoint.sh
RUN apt-get install -y openssh-server
ENTRYPOINT ["sh", "/docker-entrypoint.sh"]
# THIS PART WILL BE REPLACED IF YOU PASS SOME OTHER COMMAND TO docker RUN
CMD while true; do echo "default arg" && sleep 1; done
docker-entrypoint.sh
#!/bin/bash
service ssh restart
exec "$#"
Build command
docker build -t sshtest .
The benefit of this approach is that your ssh daemon will always start when you use docker run, but you can also specify optional arguments e.g.:
docker run sshtest will print default arg every 1 second
whether docker run sshtest sh -c 'while true; do echo "passed arg" && sleep 3; done' will print passed arg every 3 seconds
I had the same problem.
Luckily I could solve it by checking kenorb answer and adapting it to my Dockerfile:
https://stackoverflow.com/a/61738823/4058295
It's worth a try :)