Intelligent cache of ADD --checksum download

[hholst80]

I would like to see the following feature in Buildah, to achieve feature parity with Buildkit.

Suppose we have the following Dockerfile (or Containerfile):

FROM scratch
ADD --checksum=sha256:f6e4d41fd5fc778b06b7891457b3620da5ecea1006c6a4a41ae998109f85a800 https://sourceware.org/pub/binutils/releases/binutils-2.42.tar.xz /

This should not pull down any file from sourceware.org if the file is already in cache and has the specified SHA256 checksum. If the local file has the same checksum as the one in the URL there is no reason to download anything.

Note that this is cached, but only so after the source has been downloaded, thus fairly useless for my use case.

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[codethief]

Not stale

[rhatdan]

@flouthoc PTAL

[flouthoc]

I'll take a look at this.

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[codethief]

Not stale.