At regular intervals, the image is created not from remote repositories but from the proxy. At first, there will be no dependencies in the proxy. But after the initial build, the image will contain the required dependencies.

The enterprise repository is empty. Dependencies will be downloaded from remote repositories, through the enterprise proxy, feeding it in the process.

The enterprise repository is filled. Dependencies are already present in the image: no download is required. Note that if in the meantime a new dependency (or a new version thereof) is required, it will be downloaded during app build, but only it - which makes download time short. This allows to provision it into the enterprise repo, available for the next app and finally into the image.