wip alpine

BUILD

@@ -23,13 +23,7 @@ go_binary(
     visibility = ["//visibility:public"],
 )
 
-container_bundle(
-    name = "alpine",
-    images = {"base": "@alpine//image"},
-)
-
 rootfs(
-    name = "alpine-rootfs1",
-    src = ":alpine.tar",
-    output = "alpine-rootfs.tar",
+    name = "alpine-rootfs",
+    src = "@alpine//image:image",
 )

rules.bzl

@@ -1,30 +1,26 @@
 def _rootfs_impl(ctx):
-    output = ctx.outputs.output
+    outf = ctx.attr.name + ".tar"
+    out = ctx.actions.declare_file(outf)
     ctx.actions.run(
-        outputs = [output],
+        outputs = [out],
         executable = ctx.files._undocker[0],
         arguments = [
-            ctx.attr.src.path,
-            output.path,
+            "rootfs",
+            ctx.attr.src.files.to_list()[0].path,
+            outf,
         ],
     )
+    return [DefaultInfo(files = depset([out]))]
 
 rootfs = rule(
     doc = "Generate a rootfs from a docker container image",
     implementation = _rootfs_impl,
-    outputs = {
-        "out": "%{name}.tar",
-    },
     attrs = {
         "src": attr.label(
             doc = "Input container tarball",
             mandatory = True,
             allow_single_file = [".tar"],
         ),
-        "output": attr.output(
-            doc = "Output rootfs tarball",
-            mandatory = True,
-        ),
         "_undocker": attr.label(
             doc = "undocker cli; private and may not be overridden",
             cfg = "host",