implement docker_pull rule

[mikedanese]

I've seen hints that this is planned as future work but I'm not aware of an issue tracking it. Is anyone actively working on this? Is there anything blocking this?

[damienmg]

Yes that is in plan (last step of http://goo.gl/OZV3o0).

It will comes after #699 which should come soon.

[damienmg]

I have a prototype that's a few lines long but it relies on the docker daemon:

def _impl(repository_ctx):
  repository_ctx.file("BUILD", """
load("@bazel_tools//tools/build_defs/docker:docker.bzl", "docker_build")

docker_build(
    name = "image",
    base = ":base.tar",
    visibility = ["//visibility:public"],
)
""")
  tag = repository_ctx.attr.tag
  result = repository_ctx.execute(["docker", "pull", tag])
  if result.return_code:
    fail("docker pull failed with error code %s:\n%s" % (
        result.return_code,
        result.stderr))
  result = repository_ctx.execute([
      "docker", "save", "-o", repository_ctx.path("base.tar"), tag])
  if result.return_code:
    fail("docker save failed with error code %s:\n%s" % (
        result.return_code,
        result.stderr))

docker_pull = repository_rule(
    implementation = _impl,
    attrs = {
        "tag": attr.string(mandatory=True),
    },
)

In the full version I would like to do it outside of docker.

[yugui]

• Why do we need to wait for Feature request: pypi_package #699? Does it mean you are trying to implement the repository rule with docker-py?
• How can I help you to make it happen earlier?

[damienmg]

@yugui it does not needs to wait, it's just less a priority than #699.

To make it happens, I am waiting for some code to get OSS then this can be written without requiring docker.

[yugui]

Thank you for your reply. I understand.
I'm happy to help if there's something I can do for the rule.