Now let's see the difference between a docker image & a docker container.
Note that Docker container and Docker images are two separate things and are not interchangeable in any means. Let’s go through the basic definitions & differences of both.
- Docker Image is a combination of file system and parameters & you can think of it as a single package that holds up everything you need to run your application. You can also refer a docker image as a
- A Docker image doesn’t have any state attached to it and once built it never changes.
- A Docker image is something that you can
download, build and run.
- You can also consider a Docker image as a result of running a series of steps.
- On the contrary, The act of running a Docker image is called container. In developer’s perspective, you can think of a Docker image as a
classand Docker container as
an instance of the class. Like first you define a class then you create an instance of it.
- You can launch many containers from a single image. For example if you’ve a single image of your web application
- Docker Containers are immutable, means that any changes you make on them while running will be lost forever when you stop that container.
For example, let’s run a simple linux container by:
docker run -it alpine sh
and make a new folder in the home directory and exit and rebuild the container and you’ll see there’s no such file in the home directory. Hence Docker containers are immutable.