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Question regarding image layering


(Mario100) #1

Hi,

I’m just learning about Docker and wondered if someone could please help me to clarify something I’ve read about it.

A report stated:

"Docker allows Operations to create and manage containers, and allows Development to put content - the application - inside them.

The image layering concept in Docker allows Development to put content – applications with dependencies – inside them."

Does that mean the image layering concept allows Development to put content within the applications (that are within the containers?) If anyone could help make it a bit cleared I would really appreciate it.


(Andy Rothfusz) #2

The layers are transparent to the applications – they (typically) don’t know they are on a layered file system.

You’ll understand the layers in images better if you try to docker build a few of your own images. Each line in your Dockerfile which starts with RUN creates a new layer. FROM starts with another image and adds your layers on top.

So you could be adding content in your RUN statements, or anything else you need to do when installing your software.