Dockerfile Explained

Rule no 1 - The name of the file should be "Dockerfile" only.

Dockerfile is used to build images. It's is a text file that contains all the commands a user could call on the command line to create an image.

 Here the commands you can use in a Dockerfile are explained with examples wherever possible. Hope it helps.

 The general format of a command is "INSTRUCTIONS arguments".

 Ex : RUN echo "Hello Docker !!"

FROM

FROM <image>

The FROM instruction sets the Base Image for subsequent instructions. As such, a valid Dockerfile must have FROM as its first instruction. The image can be any valid image – it is especially easy to start by pulling an image from the Public Repositories.

Ex : FROM ubuntu

MAINTAINER

MAINTAINER <name>

This allows you to set the Author field of the generated images.

RUN

Executes a command and save the result as a new layer.

EX: RUN echo "Hi"

EXPOSE

EXPOSE <port> [<port>...]

The EXPOSE instruction informs Docker that the container listens on the specified network ports at runtime.

Ex: EXPOSE 22

ADD

ADD <src>... <dest>

Copies a file from the host system onto the container















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