Tuesday, February 28, 2017

Docker Basic Commands

Commands which are available to use in Docker to play with images or containers

## Download/Pull an image

docker pull alpine   ## alpine is an images located in local or docker hub repository

## List Docker images available locally

docker images

## Run Docker images

docker run alpine ls -l     #run command will look for image alpine locally if does not exist it will pull from docker hub, creates container and start/run a command in that container

docker run alpine echo "hello from alpine"

docker run alpine /bin/sh

Wait, nothing happened! Is that a bug? Well, no. These interactive shells will exit after running any scripted commands, unless they are run in an interactive terminal - so for this example to not exit, you need to docker run -it alpine /bin/sh

## List running containers

docker ps

## List all containers we ran

docker ps -a

## Run a container with attached tty

docker run -it alpine /bin/sh

This will drop you at /bin/sh shell in container (with tty) where you can run any command as similar to on OS

docker run -it alpine /bin/sh
/ # df -h
Filesystem                Size      Used Available Use% Mounted on
none                     18.1G      1.8G     15.3G  11% /
tmpfs                   496.2M         0    496.2M   0% /dev
tmpfs                   496.2M         0    496.2M   0% /sys/fs/cgroup
                         18.1G      1.8G     15.3G  11% /etc/resolv.conf
                         18.1G      1.8G     15.3G  11% /etc/hostname
                         18.1G      1.8G     15.3G  11% /etc/hosts
shm                      64.0M         0     64.0M   0% /dev/shm
tmpfs                   496.2M         0    496.2M   0% /proc/kcore
tmpfs                   496.2M         0    496.2M   0% /proc/timer_list
tmpfs                   496.2M         0    496.2M   0% /proc/timer_stats
tmpfs                   496.2M         0    496.2M   0% /proc/sched_debug
tmpfs                   496.2M         0    496.2M   0% /sys/firmware

## Inspect any image/container. INSPECT will Return low-level information on a container or image in JSON format

docker inspect alpine

## Remove containers

get the Container ID

docker ps -a

##docker rm container-ID

 docker rm 2db0a4bcb909

## Remove images

get the images IDs

docker images

## docker image rm image-ID   # but make sure containers using this image should be removed first else they will be in unstable state if image is removed

docker image rm 48b5124b2768


  • Images - The file system and configuration of our application which are used to create containers
  • Containers - Running instances of Docker images — containers run the actual applications. A container includes an application and all of its dependencies. It shares the kernel with other containers, and runs as an isolated process in user space on the host OS
  • Docker daemon - The background service running on the host that manages building, running and distributing Docker containers
  • Docker client - The command line tool that allows the user to interact with the Docker daemon
  • Docker Hub - A registry of Docker images. You can think of the registry as a directory of all available Docker images

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