Containers

A container is a way to create isolated env that can run code while sharing a single OS.

Run a container

docker container run -p 9999:80 httpd:2.4

The --detach flag can be used to run the container in background:

docker container run --detach -p 9999:80 httpd:2.4

List containers

docker container ls

Run commands on container

docker container exec my_container_name du -mh

Attaching a Shell to a Container

To get a shell inside the container:

docker container exec -it my_container_name /bin/bash

PATH=$PATH:/usr/games/
export PATH

Dockerfiles

Dockerfile -> create an image -> to generate a container

Inside a file named Dockerfile.

Dockerfile example

FROM httpd:2.4
EXPOSE 80
RUN apt-get update && apt-get install -y fortunes
COPY page.html /var/www/html/
LABEL maintainer="moby-dock@example.com"

Building an Image From a Dockerfile

docker image build --tag web-server:1.0 .

End the command with a single . so it knows to look for the Dockerfile in the same folder that the command is run in.

docker image ls


docker container run -p 80:80 web-server:1.0

Volumes

It is possible to copy files into a container but files will be lost when container stops.

docker container cp page.html my_container_name:/var/www/html/.

A better solution is to use volumes. Data volumes expose files on your host machine to the container.

Creating a Volume

docker run -d -p 80:80 -v /my-files:/var/www/html web-server:1.1

Shared folder between /my-files on host machine and the html folder in the container