Docker Cheatsheet

Images

One can download (pull) a docker image from Docker Hub or respective websites:

# docker pull <image-name>:<tag>
docker pull tensorflow/tensorflow:2.4.0-gpu-jupyter

Check the downloaded images with:

docker images

Sometimes we may need to do something on an image without saving or alloting extra space. To create and run a temporary container to be deleted on stopping:

docker run --rm -it tensorflow/tensorflow:2.4.0-gpu-jupyter

Containers

Create a new container from an image with following flags 1. -v: for telling docker to use a shared directory between host and container 2. -p \<host-port\>\<container-port\>: is to use port forwarding, an application running on <container-port> can be accessed only with <host-port> in host. 3. --name generates a name for the container for easy reference in other commands 4. --gpus all tells docker to use all GPUs available on host 5. --memory-swap Restricts RAM+Swap usage 6. -it makes sure container awaits after starting instead of instantly shutting down if no startup scripts are configured.

To create new container with default params:

docker create tensorflow/tensorflow:2.4.0-gpu-jupyter

To create new container with manual params:

docker create -it \
-v \path_in_host:\path_in_container \
-p9000:8888 \
--name aaai \
--cpus 2 \
--gpus all \ # To use specific gpus: --gpu '"device=0,2"'
--memory 90g \ # Uses 90g memory
--memory-swap 100g \ # --memory-swap is a modifier flag that only has meaning if --memory is also set. In this case 10g of swap will be used.
tensorflow/tensorflow:2.4.0-gpu-jupyter

Update some of the above configurations after container creation:

# change RAM limit of a container named "aaai"
docker update --memory-swap 50g aaai

Note: In general, changes made to container persist when container is stopped.

Check containers:

docker ps # shows running containers
docker ps -a # shows all containers

Start a container (default script will be executed with this if any):

# docker start <container-name>
docker start aaai

Stop a container:

# docker stop <container-name> 
docker stop aaai

Delete a container:

# docker rm <container-name>
docker rm aaai

Go to a running container’s shell:

#docker exec -it <container-name> bash
docker exec -it aaai bash # -it stands for interactive

Execute any command on a running container without opening a shell in container:

# docker exec -it <container-name> <command>
docker exec -it aaai jupyter notebook list

Check container logs (including shell commands output):

# docker logs <container-name>
docker logs aaai

System

Check all images, all containers and space occupied by them:

docker system df -v

Set up rootless docker

Refer to this guide: https://docs.docker.com/engine/security/rootless/

Main steps:

Run dockerd-rootless-setuptool.sh install.
Setup PATH and DOCKER_HOME as suggested by command output.
systemctl --user restart docker.
Try docker images to check if things worked.
Try docker run --rm hello-world to check if things really worked.