Best Practices for Writing Dockerfiles

3 Questions

ADD

ENV

CMD

Study Notes

A Dockerfile is a text document that contains all the instructions that a user may use to create an image from the command line.
The scope of this article is to provide an overview of some best practices for writing Dockerfiles, including the use of various Dockerfile instructions.
Some best practices to help you write Dockerfile include, but are not limited to - separating of concern, avoiding unnecessary installations, reusing already-built images, and having a limited number of layers.
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 sets environment variables both during the build and when running the docker image.
The CMD statement defines the entire command to be executed.
The CMD command launches the software required in a container.
The main purpose of CMD is to launch the software required in a container.
When two arguments are specified, it maps a host path into a container path.
When one argument is specified, it creates a volume that can be inherited by the later containers.
WORKDIR sets the directory that the container starts in for all future Dockerfile commands.

3 Questions