Docker

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Docker commands

run - start a container

#docker run nginx

list all running containers

#docker ps

list all containers

docker ps -a

stop container

#docker stop <name/id>

remove container

# docker rm <name/id>

list available images

# docker images

remove an image

first stop all running containers of the images

#docker rmi nginx

how to download an image

#docker pull nginx

or download and run

# docker run nginx

execute commands on a docker container

# docker exec <container_name> <command>

example

# docker exec distracted_disk cat /etc/hosts

run - attach / detach

by default docker container runs on attach mode

run in attach mode

(the console is confined to the output)

#docker run kodekloud/web-app

run in detach mode

(the console is not confined to the output)

#docker run -d kodekloud/web-app

make a detach running command attach

docker attach <detach id>

docker terminal mapping

when we run docker container it runs as a isolated process and by default all the input and output is blocked we must allow our docker to interactive and be able to publish the docker terminal on our standard output for that we will use tag

# docker run -it <kodekloud/simple-prompt-docker>

port mapping

by default all docker runs on isolated processes that don't interact with outside world

how to access your application inside docker host

use docker container ip (every docker container have its own ip but it is internal and can only be accessed inside container)
use the docker host ip (map port of container to host )

how data is persisted in docker container

note all container`s are isolated and have isolated data storage and all the data is removed when the container is removed

to securely store data inside container we will map a storage location outside of container to a location inside container

inspect container

# docker inspect <container_name/id>

check logs of a container

# docker logs <name/id>

Advanced docker commands

run docker commands using tags

# docker run ubuntu:17.10 cat /etc/*release*

to convert a detached mode running container to attach mode

# take the container id

# docker attach <id>

how to get the internal ip of a docker container

# docker inspect <id>

then check the network section there is ip address

or to access using port mapping

# docker run -p 8080:8080 jenkins

save container data

# make a local directory

# mkdir my-jenkins-data

then map the data inside container to the created directory on the host

# docker run -p 8080:8080 -v /root/my-jenkins-data:/var/jenkins_home -u root jenkins

this configuration will store the jenkins data in /root/my-jenkins-data folder

how to create your own image ??

first write down the steps you would perform while deploying the app

write step by step

docker file

layered architecture

dockerfile builds the steps in a layered architecture for this reason if one layer have some problem the only that layer needs to built and other layer stay as it is