I'm starting my custom docker container (OpenSuse, PHP, Apache, some add-ons) this way:
docker build --build-arg http_proxy=http://user:pwd#ip:port -t prefix/myapp myapp
create --name=myapp --hostname=myapp-p 80:80 -v ${PWD}/myapp:/srv/www/myapp prefix/myapp
docker start myapp
This works perfectly. I can stop and later start the container. However, if I reboot my host system (Windows 10), I'm not able to start the container again. When I try to, the container immediately exits.
How can this be? As stated above, I use the -p and -v flags to map ports and mount a directory.
This is the output of...
docker logs myapp
-> httpd (pid 1) already running
May or may not be your problem (the logs will be telling), but I ran into an issue with docker on windows where the container tries to start before the file system is ready, which causes an error with the volume mounts. I never found a great solution aside from running a task that verifies the volume mount and restarts the container if it failed.
Related
I am rather new to docker images and am trying to set up a selenium/standalone-firefox image linked to a local folder.
I'm running Docker version 19.03.2, build 6a30dfc on Windows 10 and have unsuccessfully tried figuring out the correct working of the docker run -v syntax because it either is unspecific (i.e. too little context for me to make sense of it) or on the wrong platform).
Running docker as admin the the cmd, I used docker run -d -v LOCAL_PATH:C:\Users\Public.
This throws docker: Error response from daemon: invalid mode: \Users\Public as an error message.
I want to bind the running container to the folder C:\Users\Public (or another folder on the host machine - this is for illustration purposes).
Can someone point me to the (I fear obvious) mistake I'm making? I essentially want to achieve the container's output data (for later scraping) being stored in the host machine's folder C:\Users\Public. The container's output folder should be named myfolder.
** EDIT **
Digging around, I found this (see Volume Mapping).
I have thus tried the following code:
>docker run -d -p 4444:4444 --name selenium-hub selenium/hub
>docker run -d --link selenium-hub:hub -v C:/Users/Public:/home/seluser/Downloads selenium/node-chrome
while the former works fine (it only runs the container), the latter throws the error:
docker: Error response from daemon: Drive has not been shared.
Docker for Windows (and Mac) require you to share drives to be able to volume mount - https://docs.docker.com/docker-for-windows/ (Under Shared drives).
You should be able to find it under your Docker Settings > Shared Drives. Ensure your C:\ is selected and restart the daemon. After that, you can run:
docker run -d --link selenium-hub:hub -v C:/Users/Public:/home/seluser/Downloads selenium/node-chrome
base on the documation:
https://github.com/SeleniumHQ/docker-selenium
this path does not exist in container and its linux container.
"C:\Users\Public\Documents\TMP_DOCKERS\firefox selenium/standalone-firefo"
When I run the example from the Docker doc in the "Viewing our web application container" section, i.e.,
docker run -d -P training/webapp python app.py
...I'm able to view the "Hello World" output in a browser. Success. This seems to indicate that the network I'm on may not be the problem.
Now I'm trying to view a container that runs a webdriver suite (test automation of a browser). Based on the output in docker logs -f, the webdriver suite runs to completion. But when I try to point a browser at the webdriver container (which is running the browser), I get a error saying:
ERR_CONNECTION_REFUSED
Here are the steps I'm following:
Start webdriver container with this command
docker run -d -p 8080:5000 "/bin/bash" "-c" "/dir1/dir2/filename.sh $PARAMETER1 $PARAMETER2"
point a browser to:
http://subdomain.mydomain.com:5000
Docker output:
user#server$ docker ps -l
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
2fa83fc0401a 65525ab9ad78 "/bin/bash -c '/opt/y" 55 minutes ago Up 55 minutes 2222/tcp, 0.0.0.0:8080->5000/tcp
user#server$ docker inspect --format '{{ .NetworkSettings.IPAddress }}' 2fa83fc0401a
111.22.33.4444
Other info:
Server config: Ubuntu 14.04
Docker version: 1.8.1, build d12ea79
I've reviewed the following questions but I'm not running on a VM and I'm not running NodeJS.
Unable to view rails app running in docker container from browser
Docker: Unable to specify port for a running container
Does anyone have suggestions on how I might troubleshoot this problem? Any assistance gratefully accepted.
:) jay
Update 1:
Based on the NodeJS question noted above, I'm thinking that I'm not setting a port correctly in the Dockerfile. Maybe this is as simple as setting the correct port for Selenium?
Update 2: as #hunter noted, I had the ports in the wrong order, but switching the ports does not resolve the problem. I think the bigger problem is that I was assigning the wrong port. So, I changed docker run -d -p 8080:5000 to docker run -d -P. When I did that, I got the following output:
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
f375251b61d7 65525ab9ad78 "/bin/bash -c '/opt/y" About an hour ago Up About an hour 0.0.0.0:33073->2222/tcp
I then pointed the browser to that port: http://subdomain.mydomain.com:33073
But I still get the same error: ERR CONNECTION REFUSED
I think you're using the wrong port - the external port is 8080 not 5000.
I am attempting to dockerize a GUI app and have had some success. If I build the dockerfile into an image and then perform a docker run --name testcontainer testimage it appears that the process begins but the abruptly stops. I then check the container with docker ps to confirm no containers are running. Then I check docker ps -a and can see that it exited with status code exit(0). Then if I run the command docker start testcontainer, it appears to start the ENTRYPOINT command again, but this time it is able to continue and the GUI pops up.
My best guess is that I think that when I run the docker run command, the process begins but might be forked into a background process, causing the container to exit since the foreground process has ended. Although that could be way off because you would think the docker start command would result in the same outcome. I was thinking of trying to force the process to stay in the foreground, but do not know how to do that. Any suggestions?
UPDATE: I editted my Dockerfile to use supervisord to manage the starting of the GUI app. Now my docker run command will start supervisor, which will start my GUI app, and it works. Some things to note about this are that supervisor shows:
INFO spawned: myguiapp with pid 7
INFO success: myguiapp entered RUNNING state
INFO: exited: myguiapp (exit status 0; expected)
Supervisor and the container are still running at this point, which seems to indicate that the main process kicks off a child process. Since supervisor is still running, my container stays up and the GUI app does show up and I can use it. When I close the GUI, supervisor reports:
CRIT reaped unknown pid 93
Supervisor remains running, causing the container NOT to close. So I have to CTRL-C to kill supervisor. I'd rather not use supervisor, but if I need to, I would like for supervisor to close itself gracefully when that child process ends. If I could figure out how to get my container or supervisor to track child processes of the main process, then I think this would be solved.
The first issue is probably because your application requires a tty and you are not allocating a pseudo tty. Try running your container like this:
docker run -t --name testcontainer testimage
When you do a docker start the second time around it somehow allocates the pseudo-tty and the process keeps on running. I tried it myself. I couldn't find this info anywhere in the Docker docs though.
Also, if your UI is interactive you would want:
docker run -t -i --name testcontainer testimage
I created a Django application which runs inside a Docker container. I needed to create a thread inside the Django application so I used Celery and Redis as the Celery Database.
If I install redis in the docker image (Ubuntu 14.04):
RUN apt-get update && apt-get -y install redis-server
RUN pip install redis
The Redis server is not launched: the Django application throws an exception because the connection is refused on the port 6379. If I manually start Redis, it works.
If I start the Redis server with the following command, it hangs :
RUN redis-server
If I try to tweak the previous line, it does not work either :
RUN nohup redis-server &
So my question is: is there a way to start Redis in background and to make it restart when the Docker container is restarted ?
The Docker "last command" is already used with:
CMD uwsgi --http 0.0.0.0:8000 --module mymodule.wsgi
RUN commands are adding new image layers only. They are not executed during runtime. Only during build time of the image.
Use CMD instead. You can combine multiple commands by externalizing them into a shell script which is invoked by CMD:
CMD start.sh
In the start.sh script you write the following:
#!/bin/bash
nohup redis-server &
uwsgi --http 0.0.0.0:8000 --module mymodule.wsgi
When you run a Docker container, there is always a single top level process. When you fire up your laptop, that top level process is an "init" script, systemd or the like. A docker image has an ENTRYPOINT directive. This is the top level process that runs in your docker container, with anything else you want to run being a child of that. In order to run Django, a Celery Worker, and Redis all inside a single Docker container, you would have to run a process that starts all three of them as child processes. As explained by Milan, you could set up a Supervisor configuration to do it, and launch supervisor as your parent process.
Another option is to actually boot the init system. This will get you very close to what you want since it will basically run things as though you had a full scale virtual machine. However, you lose many of the benefits of containerization by doing that :)
The simplest way altogether is to run several containers using Docker-compose. A container for Django, one for your Celery worker, and another for Redis (and one for your data store as well?) is pretty easy to set up that way. For example...
# docker-compose.yml
web:
image: myapp
command: uwsgi --http 0.0.0.0:8000 --module mymodule.wsgi
links:
- redis
- mysql
celeryd:
image: myapp
command: celery worker -A myapp.celery
links:
- redis
- mysql
redis:
image: redis
mysql:
image: mysql
This would give you four containers for your four top level processes. redis and mysql would be exposed with the dns name "redis" and "mysql" inside your app containers, so instead of pointing at "localhost" you'd point at "redis".
There is a lot of good info on the Docker-compose docs
use supervisord which would control both processes. The conf file might look like this:
...
[program:redis]
command= /usr/bin/redis-server /srv/redis/redis.conf
stdout_logfile=/var/log/supervisor/redis-server.log
stderr_logfile=/var/log/supervisor/redis-server_err.log
autorestart=true
[program:nginx]
command=/usr/sbin/nginx
stdout_events_enabled=true
stderr_events_enabled=true
I have a basic hello world Node application written on express. I have just dockerised this application by creating a basic dockerfile in the applications root directory. I created a docker image, and then ran that image to run it in a running container
# Dockerfile
FROM node:0.10-onbuild
RUN npm install
EXPOSE 3000
CMD ["node", "./bin/www"]
sudo docker build -t docker-express
sudo docker run --name test-container -d -p 80:3000 docker-express
I can access the web application. My question is.. When I made code changes to my application, eg change 'hello world' to 'hello bob', my changes are not reflected within the running container.
What is a good development workflow to update changes in the container? Surely I shouldn't have to delete and rebuild the images after each change?
Thank you :)
Check out the section on Sharing Volumes. You should be able to share your host volume with the docker container and then any time you need a change you can just restart the server (or have something restart it for you!).
Your command would look something like: sudo docker run -v /src/webapp:/webapp --name test-container -d -p 80:3000 docker-express
Which mounts /src/webapp (on the host) to /webapp (in the container).