+def docker_image_format(image_hash):
+ """Return the registry format ('v1' or 'v2') of the given image."""
+ cmd = popen_docker(['inspect', '--format={{.Id}}', image_hash],
+ stdout=subprocess.PIPE)
+ try:
+ image_id = next(cmd.stdout).decode().strip()
+ if image_id.startswith('sha256:'):
+ return 'v2'
+ elif ':' not in image_id:
+ return 'v1'
+ else:
+ return 'unknown'
+ finally:
+ check_docker(cmd, "inspect")
+
+def docker_image_compatible(api, image_hash):
+ supported = api._rootDesc.get('dockerImageFormats', [])
+ if not supported:
+ logger.warning("server does not specify supported image formats (see docker_image_formats in server config).")
+ return False
+
+ fmt = docker_image_format(image_hash)
+ if fmt in supported:
+ return True
+ else:
+ logger.error("image format is {!r} " \
+ "but server supports only {!r}".format(fmt, supported))
+ return False
+