Docker¶

List downloaded images¶

docker images
OR
docker image ls

List running images¶

docker ps

List running and stopped images¶

docker ps --all 
OR
docker ps -a

Download from dockerHub¶

docker pull <imageName>:<TagName>

Run container¶

run verifies if the image is already available locally. If not, it downloads the image, if available on the docker hub and then runs it.

docker run <imageName>:<TagName>

Run the container in the background¶

d refers to detached mode.

docker run -d redis:7.2-bookworm

Run container in interactive mode¶

docker run -it <imagename>:<tagname>

Stop a running container¶

docker stop <container name>

Port binding example¶

Run nginx server and use the port binding to see the page on the localhost

docker run nginx

>> Unable to find image 'nginx:latest' locally
>> latest: Pulling from library/nginx

The above command doesnt do much, as the port binding is not done to see the default page in the browser.

docker run -p 80:80 nginx

>> Unable to find image 'nginx:latest' locally
>> latest: Pulling from library/nginx

To bind the port to port number 5000 in your system

docker run -p 5000:80 nginx

>> Unable to find image 'nginx:latest' locally
>> latest: Pulling from library/nginx

Delete all the stopped containers¶

Stopped containers accumulate unless you delete it. It can be deleted from the docker desktop or using below command.

docker container prune

Automatically delete the container after it stops¶

Use --rm flag to the run command to automatically delete the container after it is stopped.

docker run -p 5000:80 nginx --rm -d

>> Unable to find image 'nginx:latest' locally
>> latest: Pulling from library/nginx

Environment variables¶

To pass environment variables at run time

docker run -e JIRA_PAT=MYuOUgiy22435FHTFyt87108cywiu9

Slim and alpine images¶

Slim images are lower in size compared to the original image. Alpine images are still more smaller in size compared to slim. Slim images are mostly based on the debian distro whereas Alpine images are based on Arch linux.

Run a command in a running container¶

To run a command or open the bash in an already running container;

docker exec -it objective_poincare /bin/bash

This opens a shell in the container in the already running container objective_poincare

Build a a custom docker image¶

To build a custom docker image you need a Dockerfile

# Dockerfile


FROM debian:bookworm-slim
RUN apt update
RUN apt install -y python3 python3-pip git
WORKDIR /app
RUN git clone https://github.com/deluge-torrent/deluge.git
WORKDIR /app/deluge
CMD [ "bash" ]

This command is used to build a Dockerfile to an image. . represent the path where docker has to look to find the Dockerfile , current directory in this case.

docker build -t debian:1.0.0 .

OR

docker build -t debian:1.0.0 -f <path to Dockerfile>