Learning Docker: Creating a base image using a Dockerfile

One can create an image using a script called a Dockerfile, a script with instructions on how to build an image. Each instruction may result in an intermediate image created in your local docker repository.

Commonly used Dockerfile instructions

• FROM [base-image]
• MAINTAINER [name] [email]
• RUN [command]
• ADD [src] [dest]
• CMD [command]
• EXPOSE [port]

Layering Commits

RUN deserves a special mention: this instruction enables an image to be composed of snapshots, with each snapshot layered on top of another.

Building

To build an image from a Dockerfile, run this command from where the Dockerfile is kept:

$ docker build .

$ docker images

Dockerfile Reference