Add ebuild testing script

overlaytools/ebuildtester.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env sh
+
+# Generates a docker container that replicates "fresh" Gentoo installations
+# See https://wiki.gentoo.org/wiki/Ebuildtester
+#
+# This script sets some baseline arguments, but additional arguments can be
+# passed into the script as if you were using the `ebuildtester` directly
+#
+# NOTE: `--overlay-dir` gets mounted to `/var/lib/overlays/<overlay-name>`
+#       inside the container
+
+ebuildtester \
+    --portage-dir /var/db/repos/gentoo/ \
+    --overlay-dir $(git rev-parse --show-toplevel) \
+    --rm \
+    --update \
+    --pull \
+    --install-basic-packages \
+    --threads $(nproc) \
+    --unstable \
+    --with-vnc \
+    --manual ${@}