Dockerfile Basics

• The FROM statement in a Dockerfile defines which image to download and start from.
• A Dockerfile can have multiple FROM statements, which means that the Dockerfile produces more than one image.
• The MAINTAINER statement defines the author of the Dockerfile and how to contact them in case of any bugs.
• The RUN statement defines what process will be running inside the container at runtime by specifying a command to run through the shell and waiting for it to finish.
• The ADD statement is used to copy new files, directories, or remote file URLs into the filesystem of the image.
• The ENV statement is used to set environment variables for the container.
• The ENTRYPOINT statement specifies the starting of the expression to use when starting your container.
• The CMD statement defines the entire command to be executed.
• The CMD [ command ] syntax allows you to run multiple commands together.
• The Dockerfile is a text file used by the Docker engine to create a container from an image.
• A Dockerfile can contain instructions for how to build a container from an image.
• The image can be a snapshot of an existing container, or it can be created from scratch.
• The EXPOSE statement allows you to expose ports on a host machine so that containers can use them.
• The WORKDIR statement sets the working directory for the container.
• The VOLUME statement defines shared or ephemeral volumes on a host machine.

Test your knowledge of Dockerfile instructions and their functions in containerization. Learn about defining images, setting environment variables, file operations, and container commands.