Suppose I have a/Dockerfile:

FROM debian
RUN date > /hello

and b/Dockerfile:

FROM pxeger/a
RUN date >> /hello

and docker-bake.json:

{
  "group": {
    "default": {
      "targets": ["a", "b"]
    }
  },
  "target": {
    "a": {
      "context": "a/",
      "tags": ["pxeger/a:latest"]
    }
    "b": {
      "context": "b/",
      "tags": ["pxeger/b:latest"]
    }
  }
}

Right now, if I run docker buildx bake, the image pxeger/a will be pulled from the registry before either image is built, even though the build process will produce an a. This means:

• needless extra pulls are made
• the final resulting containers cannot share all the layers of a, because b was built upon the old version of a
• if a does not exist on the registry, the build will fail

There seems to be no workaround for this. Even if bake doesn't want to include a Dockerfile parser and dependency resolution algorithm, it would be good to at least be able to manually force a dependency build order. (changing the order of group.default.targets doesn't work).

Of course this somewhat reduces the possible parallelism because a and b can't be built at the same time now.