Only allow one of 'packages' or 'installables_tar'. (#33)
diff --git a/container/rules/docker_toolchains.bzl b/container/rules/docker_toolchains.bzl
index 0756568..ce74833 100644
--- a/container/rules/docker_toolchains.bzl
+++ b/container/rules/docker_toolchains.bzl
@@ -22,6 +22,9 @@
if "debs" in kwargs:
fail("debs is not supported.")
+ if "packages" in kwargs and "installables_tar" in kwargs:
+ fail("'packages' and 'installables_tar' cannot be specified at the same time.")
+
has_no_packages = "packages" not in kwargs or kwargs["packages"] == []
if has_no_packages and "additional_repos" in kwargs:
fail("'additional_repos' can only be specified when 'packages' is not empty.")
