Docker Image vs Container

Images can exist without containers, whereas a container needs to run an image to exist. Therefore, containers are dependent on images and use them to construct a run-time environment and run an application. The two concepts exist as essential components (or rather phases) in the process of running a Docker container.

1. What is difference between Docker image and container?
2. Why are Docker images so valuable?
3. What happens when you run a docker image?
4. What is Docker image file?
5. What is Kubernetes vs Docker?
6. What is difference between virtual machine and Docker container?
7. Can a docker image run on any OS?
8. What are Docker image layers?
9. Can you create your own Docker images?
10. Can a docker container have multiple images?
11. What is the difference between Docker run and Docker start?
12. Why do we use Docker containers?

What is difference between Docker image and container?

Docker Image is a set of files which has no state, whereas Docker Container is the instantiation of Docker Image. In other words, Docker Container is the run time instance of images.

Why are Docker images so valuable?

A Docker image is a read-only template that contains a set of instructions for creating a container that can run on the Docker platform. It provides a convenient way to package up applications and preconfigured server environments, which you can use for your own private use or share publicly with other Docker users.

What happens when you run a docker image?

When you run an image in a container, Docker downloads the image to your computer. This local copy of the image saves you time. Docker only downloads the image again if the image's source changes on the hub.

What is Docker image file?

A Docker image is a file, comprised of multiple layers, that is used to execute code in a Docker container. An image is essentially built from the instructions for a complete and executable version of an application, which relies on the host OS kernel.

What is Kubernetes vs Docker?

A fundamental difference between Kubernetes and Docker is that Kubernetes is meant to run across a cluster while Docker runs on a single node. Kubernetes is more extensive than Docker Swarm and is meant to coordinate clusters of nodes at scale in production in an efficient manner.

What is difference between virtual machine and Docker container?

Docker is container based technology and containers are just user space of the operating system. ... In Docker, the containers running share the host OS kernel. A Virtual Machine, on the other hand, is not based on container technology. They are made up of user space plus kernel space of an operating system.

Can a docker image run on any OS?

No, Docker containers can't run on all operating systems directly, and there are reasons behind that. Let me explain in detail why Docker containers won't run on all operating systems. Docker container engine was powered by the core Linux container library (LXC) during the initial releases.

What are Docker image layers?

What Are Docker Image Layers?

• Each layer is an image itself, just one without a human-assigned tag. ...
• Each layer stores the changes compared to the image it's based on.
• An image can consist of a single layer (that's often the case when the squash command was used).
• Each instruction in a Dockerfile results in a layer.

Can you create your own Docker images?

In general, there are two ways to create a new Docker image: Create a Docker image from an existing container: In this case, you start with an existing image, customize it with the changes you want, then build a new image from it.

Can a docker container have multiple images?

In the later versions of docker, it allows us to use what is called multi-stage Dockerfile with the help of two particular commands - FROM and AS. We can use multiple FROM commands combined with AS commands in our Dockerfile where the last FROM command will actually build the image.

What is the difference between Docker run and Docker start?

Start will start any stopped containers. This includes freshly created containers. Run is a combination of create and start. It creates the container and starts it.

Why do we use Docker containers?

Because Docker containers encapsulate everything an application needs to run (and only those things), they allow applications to be shuttled easily between environments. Any host with the Docker runtime installed—be it a developer's laptop or a public cloud instance—can run a Docker container.