bake --no-cache for specific target

[devinrsmith]

Is it possible to configure --no-cache for only the new layers introduced by a specific target with bake?

FROM <xyz> as layer-2
RUN ...

FROM layer-2 as layer-3
RUN ...

group "default" {
    targets = [
        "layer-2",
        "layer-3"
    ]
}

target "layer-2" {
    tags = [ "layer-2" ]
    target = "layer-2"
}

target "layer-3" {
    tags = [ "layer-3" ]
    target = "layer-3"
    # cache-from = [ "type=parents" ]
    # or
    # cache-to = ["type=skip"]
}

IE, I want the RUN from layer-2 to be cached, and I want layer-3 to build off of the existing layer-2, but I don't want layer-3's RUN to ever be cached. I could achieve this by explicitly introducing cache-breaking logic as the first step in the layer-3 Dockerfile, but it would be able to nice to be able to express this workflow at the build-tooling level.

I imagine hypothetical configuration for this might work by blocking it on the way in cache-from = [ "type=parents" ], or not writing to the inline cache on the way out cache-to = ["type=skip"].

[tonistiigi]

#860