docker Image

1. Docker Image is a collection of file system rootfs (base) + ufs + appfs

2. 1 COPY of image of get mounted to each container.

3. Image name is the same as repo name

4. repo can be stored in registry (dockerhub etc)

5. Docker images contains multiple file system and each file system is referred to as layer.

6. Base layer is always — root file system

7. When we create a container – all layers are merged into 1 layer and that get mounted to container.

8. In case of conflict between a layers – top layer always win. this means that suppose 2 layers have a file with the same name then the file which is in the upper layer will be the one that will appear in the merged layer

9. If we stop the container : merge layer disappears

10. Each layer of a Docker image is viewable under /var/lib/docker