I have managed to break my docker container. My container is based on baseimage-docker and I have placed an infinite loop in the the /etc/rc.local script. Now I need some way to edit the rc.local file inside the container without SSH since the SSH daemon will not run (because it runs after /etc/rc.local). Is there any way to fix this?
you need to docker exec -it container_id /bin/bash so that you will have a tty inside the container, see the doc https://docs.docker.com/reference/commandline/cli/#exec and if you have docker version < 1.3 you can use nsenter https://github.com/jpetazzo/nsenter
Related
Like in docker we can enter a container by and have an interactive shell
docker-compose exec containername /bin/bash
Similary in the script in gitlab CI/CD can we enter into it. Like it provides an interactive shell
Eg:
build:
stage: build
script:
- pwd; ls -al
HERE I WANT TO HAVE AN INTERACTIVE SHELL SO THAT I CAN CHECK FEW THINGS
I think we need to do an small detour here and explain how jobs are working in GitLab CI.
Each job is an encapsulated docker container. The container only executes things you like to be executed within the script directive. By default the jobs on shared runners are using a ruby container image.
If you want to check, what you have available within your image, or you want try things out locally. You can do so running a container with this image locally and mounting your project folder into it.
docker run --rm -v "$(pwd):/build/project" -w "/build/project" -it <the job image> /bin/bash # or /bin/sh or whatever shell is available in the image.
# -v mounts the current directory int /build/project in your container
# -w changes the working directory to the mounting point
# /bin/bash starts the shell, it might be that there are others within the image
If you want to use a different docker image, lets say because you are running some other build tool, you can specify this with the image directive like:
build:
image: maven:latest
script:
- echo "some output"
You do have the functionality available within your job, which is provided by the image. As the job will run within a container of that image.
You can even use some tools like https://github.com/firecow/gitlab-ci-local to verify this locally. But in the end those are just docker images, and you can easily recreate the flow on your own.
I would like to, on startup, copy contents of my bucket to the VM with the Container Optimized OS. When the server shuts down I'd like to save the changes back to the bucket.
I've tried making a startup script
#!/bin/bash
toolbox
gsutil cp -r gs://my-bucket/
However, this causes the VM to fail on startup despite this script working if I run it manually.
I think I found a reasonable solution. My script has changed to
#! /bin/bash
toolbox --bind=/home/username/bucket-folder:/my-bucket <<< "gsutil cp -r /my-bucket/* gs://my-bucket"
So what happens is we need to call toolbox --bind to bind a folder from the server to the toolbox container. Then we use <<< to pass the whole command to the container when it starts up so we copy to the newly bound directory so it goes back to the server.
Now when I bound the directory in my docker container, everything is there!
I just tried:
#! /bin/bash
gsutil cp -r gs://my-bucket /
And it worked for me. What is the toolbox command that you are executing previously?
Anyway you can see what is failing in the Serial Port Output.
EDIT: In the Container Optimized OS this does not work as this OS does not have the gsutil package preinstalled. Refer to #DanBaba answer.
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.
updated: added the missing docker attach.
Hi am trying to run a docker container, with -dti. but I cannot access with a terminal set to dumb. is there a way to change this (it is currently set to xterm, even though my ssh client is dumb)
example:
create the container
docker run -dti --name test -v /my-folder alpine /bin/ash
docker attach test
apk --update add nodejs
cd /my-folder
npm install -g gulp
the last command always contains ascii escape chars to move the cursor.
I have tried "export TERM=dumb" inside the running container, but it does not work.
is there a way to "run" this using the dumb terminal?
I am running this from a script on another computer, via (dumb) ssh.
using the -t which sets this https://docs.docker.com/engine/reference/run/#env-environment-variables, however removing effects the command prompt (the prompt is not shown)
possible solution 1 remove the -t and keep the -i. To see if the command has completed echo out a known token (ENDENDEND). ie
docker run -di --name test -v /my-folder alpine /bin/ash
docker attach test
apk --update add nodejs;echo ENDENDEND
cd /my-folder;echo ENDENDEND
npm install -g gulp;echo ENDENDEND
not pretty, but it works (there is no ascii in the results)
Possible solution 2 use the journal, docker can log out to the linux journal, this can be gathered as commands are executed in the container. (I have yet to fully test this one out. however the log seems to be a nicer output of what happened)
update:
Yep -t is the problem.
However if you want to see the entire process when running a command, maybe this way is better:
docker run -di --name test -v/my-folder alpine /bin/ash
docker exec -it test /bin/ash
finally you need to kill the container after all jobs finished.
docker run -d means "Run container in background and print container ID"
not start the container as a daemon
I was hitting this issue on OSx running docker, i had to do 2 things to stop the terminal/ascii/ansi escape sequences.
remove the "t" option on the docker run command (from docker run -it ... to docker run -i...)
ensure to force bash or sh shells used on osx when running the command from a script file, not the default zsh
Also
the escape sequences were not always visible on the terminal
even so, they still usually caused content corruption, even with SED brought to bear
they always were shown in my editor
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).