Switch to a single matrix builder
diff --git a/ci/build-matrix b/ci/build-matrix
new file mode 100755
index 0000000..dac838d
--- /dev/null
+++ b/ci/build-matrix
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+import glob
+import sys
+import json
+
+releases = sorted([r.split("/")[-1] for r in glob.glob("images/openstack/releases/*")])
+projects = sorted([r.split("/")[-1] for r in glob.glob("images/openstack/projects/*")])
+
+matrix = {
+ "releases": releases,
+ "projects": projects,
+}
+
+json.dump(
+ matrix,
+ sys.stdout,
+ separators=(",", ":"),
+)