OverlayFS
A union filesystem supported by the Linux kernel that mounts multiple directories in a stacked manner, allowing containers to share read-only image layers while recording changes in a writable layer. It is the underlying implementation mechanism for Docker's layered image storage.
Core Facts
Timeline (last 90 days)
A container image layer is a read-only file system snapshot in a union file system (such as OverlayFS), and each Dockerfile instruction (such as RUN, COPY) typically generates one layer.
In the layering mechanism of container images (such as the OverlayFS used by Docker), every layer of the base image is read-only, and the container runtime overlays a writable layer on top; all modifications are recorded in the writable layer, and deleting a file from a lower layer is implemented via a whiteout marker.
OverlayFS, as a union filesystem, allows multiple containers to share the read-only layers of the same image and records differences only in the writable layer, serving as the underlying support for Docker's image layering design.
All Facts (3)
OverlayFS, as a union filesystem, allows multiple containers to share the read-only layers of the same image and records differences only in the writable layer, serving as the underlying support for Docker's image layering design.
65%UnverifiedA container image layer is a read-only file system snapshot in a union file system (such as OverlayFS), and each Dockerfile instruction (such as RUN, COPY) typically generates one layer.
50%UnverifiedIn the layering mechanism of container images (such as the OverlayFS used by Docker), every layer of the base image is read-only, and the container runtime overlays a writable layer on top; all modifications are recorded in the writable layer, and deleting a file from a lower layer is implemented via a whiteout marker.
50%