Understanding Docker Image Layers
Concept and Structure of Layers A Docker image is composed of multiple read-only layers. Each layer stores the filesystem changes introduced by a command in the Dockerfile. This is similar to commits in Git. It improves efficiency by storing only the changes. Docker mounts the layers as a single filesystem using a union file system. A writable container layer is added on top of the last layer. This can be visualized as multiple transparent sheets stacked on top of each other. ...