Pass build description labels to podman build

The Compose Specification supports adding labels to the build image
which is also used in practice. Support this and pass the labels to
`podman build`.

Signed-off-by: Sebastian Wick <sebastian.wick@redhat.com>

podman_compose.py

@@ -2378,6 +2378,8 @@ async def build_one(compose, args, cnt):
  build_args.extend(get_secret_args(compose, cnt, secret, podman_is_building=True))
  for tag in build_desc.get("tags", []):
  build_args.extend(["-t", tag])
+ for label in build_desc.get("labels", []):
+ build_args.extend(["--label", label])
  for additional_ctx in build_desc.get("additional_contexts", {}):
  build_args.extend([f"--build-context={additional_ctx}"])
  if "target" in build_desc:

tests/integration/build/README.md

@@ -21,5 +21,3 @@ ALT buildno=2 port 8000 2019-09-03T15:16:38+0000
 
 as you can see we were able to override buildno to be 2 instead of 1,
 and httpd_port to 8000.
-
-NOTE: build labels are not passed to `podman build`