Docker essentials – Images and Containers

I’ll admit, I jumped into docker pretty quickly and found that I was getting a little ahead of myself.  After much googling and discussion, I’ve come to realize a couple things about docker that I think are well worth sharing.  I’m hoping to share them through a series of ‘Docker Essentials’ type posts.

NOTE: My first post was going to be about how to interact with docker on the CLI.  However, there are lots of other resources out there for that.  Namely, the really awesome docker documentation.  In addition, the CLI provides help/syntax on commands as well.  I’ll list a couple of resources that I used and try to explain along the way, but if you don’t recognize a command I’m using look it up! 

The docker user guide –
The docker CLI reference –
The docker guide book –

Working with images and Containers
On first glance, I made some assumptions about this images and containers that proved to be wrong.  So let’s start with some basics.

Images are read-only.  That is, they can never be altered.  Containers are built using images as the base.  For instance, at the end of the last post, we pulled down what’s referred to a ‘base image’ from the docker repository.  Some images are considered to be base images and they are officially created and supported by the good folks at docker.  So what happens when you modify an image?  Let’s look at the current images and see what we have…

Read the rest at


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