Redundant Blob Copying and Storing When Loading Images on the Same Host

[mike-sul]

Description

The /images/load interface and its current implementation require that all image blobs (including config and layers) be transferred through the POST request body. These blobs are temporarily stored in the <docker-data-root>/tmp/ directory before they are extracted and injected into the Docker store.

This process of transferring and storing blobs in the "tmp" directory introduces redundancy, especially when the client making the HTTP POST /images/load request is located on the same host as the Docker daemon. In such cases, the blobs are already present on the filesystem, making the temporary storage step unnecessary.

To optimize this process, the handler implementation could directly read the blobs from their original location on the filesystem and inject them into the Docker store, bypassing the redundant transfer and temporary storage steps.