Docker

About

Use-case	Command
Build image	`docker build - < Dockerfile`
Pull image	`docker pull ...`
Run a command in a new container	`docker run [OPTIONS] IMAGE [COMMAND] [ARG...]`
List images	`docker images [OPTIONS] [REPOSITORY[:TAG]]`
List containers	`docker container ls`
Remove all stopped containers	`docker container prune [OPTIONS]`

Instruction	Description
ARG	Define variables
FROM	Specify base image for building a new image
LABEL	Add metadata to an image, such as description, version, author...
RUN	Command to execute during build process Each RUN instruction creates a new layer on top of the current image
ADD	Copy files and directories
COPY	Similar to ADD, only a local file or directory
ENV	Define an environment variable.
CMD	Specify a command that will be executed when you run a container You can use only one CMD instruction in your Dockerfile
ENTRYPOINT	Defines what command will be executed when running a container
WORKDIR	Sets the current working directory for the RUN, CMD, ENTRYPOINT, COPY, and ADD instructions
USER	Set the username or UID to use for the RUN, CMD, ENTRYPOINT, COPY, and ADD instructions
VOLUME	Mount a host machine directory to the container
EXPOSE	Specify the port on which the container listens at runtime

A text document that contains all the commands you would normally execute manually in order to build a Docker image.

Basis of containers
An ordered collection of root filesystem changes and the corresponding execution parameters for use within a container runtime.
Typically contains a union of layered filesystems stacked on top of each other.
Does not have state and it never changes.