Docker Image Vs Container : Difference Between Docker Image and Container

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May 23, 2021

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Difference between Docker image and container

DevOps is extremely challenging and an opportunity for development; it requires more than technological expertise; it requires an in-depth understanding of complex technical issues and business requirements. Hence you must register and learn DevOps online for a better understanding. 

This blog will cover the difference between docker image and container. 

When considering the distinctions between docker image vs. container, it is unreasonable to compare them as they are completely contradictory entities. The components are closely tied and represent a framework specified by the Docker platform.

There is a subtle distinction between the two and they are outlined in the table below. They represent the two sides of the same coin. One is used to represent another without contradicting the other. One cannot exist without the other and they co-exist together to form a formidable pair.

Docker image vs container – The top 7 must knows 

SerialContainer in DockerImages in Docker 
1However, a container is a sequence of steps that run in both read and write representation of that file system.An image is a read only file system.
2The container is a illustration of the Image.Whereas image is the Container's outline
3They can operate by using the database server and file system supported by the image.These can be used to pack pre-configured server systems and applications.
4They require that an image be run to exist. As a result, containers depend on images to create a run-time experience and run a program.They can remain individually
5The term "container" refers to a real-world object.It is a hypothetical (logical) concept.
6However, these can be generated indefinitely using images. This is only generated once.
7To create a container from an image, run the command "docker build."To create an image, you must write a Docker file script.


What is a Container?


  • We can add a container with one or more servers, attach data storage to it, and even generate a new image based on its current state as an advantage. Additionally, it includes an image, an application interface, and a collection of standard instructions.
  • It virtualize in the app layer, unlike VMs that virtualization occurs on a hardware level. They can run isolated processes on a single machine through sharing its kernel and virtualizing the operating system. This results in incredibly lightweight containers, allowing you to save precious resources.
  • Further, they have strong isolation due to their flexibility, ensuring they do not interact with other running containers or the network that supports them. Docker states that these systems "provide the industry's best isolation functionality." As a result, you won't have to think about ensuring the stability of your system when developing an application.
  • An important aspect is the standardization of the cloud computing environment. It mostly ensures that the application works under the same circumstances and facilitates sharing with the other collaborators.

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What is an Image?


  • From a single image base, you can generate an infinite number of Docker files. Each time you alter the initial state and then save it, you develop a new template with such an extra layer on top.
  • Since these are only templates, they cannot be started or run. You will use the template as a starting point for developing a container. At its core, a container is nothing more than a running image. When a container is set, a writable layer is added to the immutable image, so you can now change it.
  • The container is based on images. The latter one has no existence and also never changes. Additionally, they are a collection of directory layers. Generally, when a container is initialized, this serves as the base file system.
  • The image-based container you build exists separately, and it can be changed. When running a containerized setting, you effectively make a read-write version of that container filesystem (docker image). This creates a container layer that enables the original copy of the image to be changed.
  • These are often attributed to as snapshots referring to their read-only feature. They are representations of software and its virtual world at a specific moment in time. Consistency has become one of Docker's best features. It facilitates DevOps learning and experiment with software in managed, secure environments.

Thus, images can be based on a series of layers, each one unique but still deriving from the previous one. When you use it to start a virtual world, the image layers reflect read-only data with which a container layer is attached.

Snapshot – Image vs Containers

  1. Virtual machines (VMs) are a type of sandboxed system that includes an entire device. Due to the virtual hardware, operating system, kernel, and applications that comprise a VM, booting it up will take several minutes.
  2. The primary distinction is the top writable layer. Essentially, all writes to the container that creates new or alters existing data which are collected in the writeable layer. Additionally, when the container is deleted, the writable layer is deleted as well. However, the underlying image remains the same.
  3. The difference between Docker Image and Container is the concept which talks about having all the files except for writeable instance is the image and having a writable instance of those files are the containers. 
  4. The containerized application provides an environment that is sandboxed where you can install and customize the OS and effective hardware setup for each virtual machine. A new technology known as docker container has recently gained popularity as the hottest trend in application development.
  5. Both concepts are key components during the operation of a container. Having a running container indicates that the process has completed its final "phase," meaning that it is based on previous phases and components. So images serve as the governing and shaping factor for containers.
  6. Although the software is relatively easy to master, new users, can be distracted by some Docker-specific terminology. It is a good concept to understand the fundamental functions of these elements. It will accelerate DevOps training on how to interact with image vs. container docker. Many users have the following questions before we get started with the DevOps certification training guide
  7. Docker is an open-source app development framework that aims to promote and simplify app development. It is a collection of platform-as-a-service items that facilitate the delivery of isolated virtualized environments for the development, deployment, and testing of applications.

An Docker image is an unchangeable database file containing the application's code, resources, plugins, tools, and other files. Users can separate apps from the underlying framework using containers, which are virtualized run-time environments. The docker containers are small, portable units that enable you to easily and quickly start. Generally, a container is used to represent a usable instance of an image. We can build, begin, alt, transfer, and remove containers using the Docker API or CLI. This is to begin with, however, let us explore more in the coming sections. 


The images represent the applications and the methods in which they can be run. Containers are image circumstances that allow for the execution of multiple containers of the same image in a different state. If you understand how a container is created, you'll immediately discover how distinct docker image vs. container is.

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