README.md

What is Dockerfile Composer

Compose a Dockerfile using snippet(s) of Dockerfile. It allows you to reuse the snippets you wrote before.

What it solves

There might be duplicated lines across different Dockerfiles, we can extract the common ones into separate snippets and use this script to compose them into a new Dockerfile without copying and pasting.

Here is my use case, I need to create different images for multiple users and I found most of my Dockerfiles came with a pattern:

1. install essential software (git, tar, which)
2. configure services (SSH)
3. install optional software (nginx, pip, gevent, node.js or boost etc.)

For part 2 and 3, the services or software might be varied based on different image requirements but the instructions are identical for the same service/software. So, extract the instructions and put them into a snippet and then cherry-pick snippets I need.

How to use

Clone git repository

https://github.com/blakey22/dockerfile-composer.git

Help

./compose.sh

Compose baseline Dockerfile without any snippets

./compose.sh --base

Compose Dockerfile from snippets

./compose.sh gcc jdk

Compose Dockerfile from snippets with designated version

./compose.sh pip jdk=7u79-b15

Modify it

The baseline Dockerfile in this repository is CentOS 6.7 with SSH enabled and few software installed (vim, tar and etc.); you may want to change baseline Dockerfile and add/change snippets to fit your needs. This script is based on the structure below to compose a Dockerfile:

Dockerfile

    +----------------+
    |     header     |
    +----------------+
    |    snippet A   |
    +----------------+
    |    snippet B   |
    +----------------+
    |    snippet ..  |
    +----------------+    
    |    snippet N   |
    +----------------+
    |     footer     |
    +----------------+

Dockerfile:

• header: resources/snippet/_header
• footer: resources/snippet/_footer
• snippetX: resources/snippet/SNIPPET_NAME