Docker Cheat Sheet

In this repository, I give some examples of docker commands.

Pulling images

You can pull images with docker pull <repository>:<tag> .

docker pull mysql:8

docker pull nginx:latest

Inspecting and gathering data from images

You can inspect an image with docker inspect <repository>:<tag>.

docker inspect mysql:8

Save an image

you can save an image to as a .tar file using docker image save -o <output-file> <repository>:<tag>.

docker image save -o nginx.tar nginx:latest

Load an image

You can load an image using docker image load.

docker image load < nginx.tar

or

docker image load -i nginx.tar

Import an image

You can import an image using docker image import <file-path> <repository>:<tag>.

docker image import nginx.tar nginx:latest

Running a container (basic)

You can run a container using docker run <repository>:<tag>.

You can read manual of this command using docker run --help.

Running a container named nginx and mapping ports

docker run -d --name nginx -p 8081:80 nginx

It will map 8081 of host to 80 of container.

note: -d detaches a container.

Display the running processes of a container

docker top <container-id or container-name>

docker top nginx

docker top db65c23ca7accf470646d42c096e86f061771bed934a7c2c0ff03f0586f66430

Removing dangling images

Dangling images are images which have REPOSITORY but TAG.

REPOSITORY                        TAG               IMAGE ID       CREATED        SIZE
alpine                            <none>            e9adb5357e84   2 days ago     5.57MB

You can remove dangling images using docker image prune.

Kill a container

You can kill a container using docker kill <container-id or name>.

docker kill db65c23ca7accf470646d42c096e86f061771bed934a7c2c0ff03f0586f66430

docker kill nginx

Installing nginx on a alpine container

~ » docker run -it alpine sh                                                            
/ # apk add nginx
fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.15/community/x86_64/APKINDEX.tar.gz
(1/2) Installing pcre (8.45-r1)
(2/2) Installing nginx (1.20.2-r0)
Executing nginx-1.20.2-r0.pre-install
Executing nginx-1.20.2-r0.post-install
Executing busybox-1.34.1-r4.trigger
OK: 7 MiB in 16 packages

Pausing a container

You can pause a container using docker pause <container-id or name>.

docker pause db65c23ca7accf470646d42c096e86f061771bed934a7c2c0ff03f0586f66430

docker pause nginx

Redirect container-id of a container to a file

docker run -d redis > myredis.cid

Limit a container

docker run -d --cpus 1.5 --memory=512m --memory-swap=512m --cpuset-cpus=0,2 nginx

Setting environment variables

docker run --rm -it -e NAME=behrad -e CLASS=dws alpine sh

After that, you can verify this setting using env command in container.

~ » docker run -it -e NAME=behrad -e CLASS=dws alpine sh                               
/ # env
CLASS=dws
HOSTNAME=d458fcfc5a64
SHLVL=1
HOME=/root
NAME=behrad
TERM=xterm
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/

Mounting a host directory to a container and changing the working directory

You can mount a volume using -v or --volume and -w or --workdir to change working directory.

docker run -v $PWD/test:/data -w /data alpine

It will mount $PWD/test of host to /data of container.

Dockerfile

Just an example ...

ARG VERSION=latest
FROM alpine:$VERSION
ENV CLASS=dws

RUN apk add nginx

EXPOSE 80/tcp

VOLUME /data

ADD . /data
COPY . /data

ENTRYPOINT ["nginx", "-s" , "start"]

@dwsclass dws-ops-005-docker

@dwsclass dws-ops-006-docker

@dwsclass dws-ops-007-docker