Container Basics

# version check

docker version

docker info

docker

# new way of running commands

docker container run (new)

docker run (still work)

Image vs Container

Image — the app we want to run, we build or others build

Container — an instance of that image running as as process

Can have many Containers running 1 Image

Docker Hub is Docker’s default image “registry” (like AppStore)

Commands

# run a container "nginx"

docker container run --publish 80:80 --detach --name webhost nginx

# it will return a container ID, use it to stop or remove container

6903032478...

# run in the background

-d / --detach

# open up port 80 on host, forward to port 80 in container

-p / --publish 80:80

# name a container

--name webhost

# list containers (running or all)

docker container ls

docker container ls -a

docker ps

docker ps -a

# run vs start: run always init new container, "start" an existing container

docker container start 690

# stop a container by ID (first 3 letters) or name

docker container stop 690

docker container stop webhost

# read logs of a container (by name of id)

docker container logs webhost

# read processes of a container

docker container top webhost

THIS IS IMPORTANT, A PROCESS RUN BY A CONTAINER IS A REAL PROCESS, JUST JUST A VM

# remove a container (use -f to force remove), multiple containers by space

docker container rm 690 abc xuz

docker container rm -f 690

# get help

docker container --help

What happens when a container run:

it looks for “nginx” image locally

look for remote image from Docker Hub

download latest version ( nginx:1.11 )

create new container

give container a virtual IP on a private network inside docker engine

open up port 80 on host, forward to port 80 in container

start container by using the CMD in the image Dockerfile

check the processes started by a container, you’ll see it is a real process ( ps aux | grep mongo )

Advanced Command

# create a mysql container named db with custom env var

docker container run -d -p 3306:3306 --name db --e MYSQL_RANDOM_ROOT_PASSWORD=yes mysql

# check log to find password of mysql

docker container logs db

# check nginx on port 80

curl localhost

# check apache httpd on port 8080

curl localhost:8080

# list all images

docker image ls

# inspect how a container in JSON

docker container inspect

# show current stats of all container

docker container stats

# run shell inside a container

docker container run -it nginx bash

docker container run -it alpine sh

docker container start -ai

docker container exec -it webhost ping webhost2 # run ping inside webhost1 to ping to webhost 2

# when we run 'bash' after container boot-up, it will stop default start-up (container will not run)