Difference Between Docker Image and Container

Docker Image

A docker image is an immutable(not modifiable) file that contains code, dependencies, libraries, tools and the whole runtime environment which is needed in order to run the application.

It has a read-only functionality, these images are also sometimes referred to as snapshots. It is a multi-layered file, build to execute the code and run the application. It can be shuttled in any environment and build to execute the code.

Images are however just a template, which cannot be started and run. We need to build a container from the image in order to run the application.  A container is, ultimately , just a running image. Once the container is created we can manipulate it and write on it which otherwise is an immutable image.

Docker Container

Docker container is nothing but a runtime instance of an image. Container in a more technical term stated as a “virtualized run-time environment where users can isolate applications from the underlying system”.

These containers are compact, portable units which you can startup an application quickly and easily. Containers provide isolation to the running system and hence they do not render or manipulate the underlying hardware nor the other containers running in the same server or computing device. Docker claims that they provide the highest level of isolation and security.

Docker Image Vs Docker Container

When debating about the difference about the docker image and the container, it isn’t good to oppose them as entities. Both the elements are closely related and are part of a system docker  platform.

Images can exists without containers, whereas containers need the existence of images on the machine. Therefore, containers are dependent on the images but the vice-versa is not required.

In nutshell, both the concepts are required and are integral part of the docker platform to deploy and execute a running application.