Fix test-system and remove stale Makefile target

Makefile

@@ -202,6 +202,10 @@ test-integration:
 
 
 # Helper target to set up SKOPEO_BINARY variable for local test targets
+# SKOPEO_BINARY only takes effect on `test-integration-local` and
+# `test-system-local` targets. It's not propagated into the container used for `test-integration` and
+# `test-system`. These targets will (build and) use skopeo binary at
+# ./bin/skopeo.
 .eval-skopeo-binary: $(if $(SKOPEO_BINARY),,bin/skopeo)
 	$(eval SKOPEO_BINARY := $(or $(SKOPEO_BINARY),./bin/skopeo))
 	@echo "Testing with $(SKOPEO_BINARY) ..."
@@ -226,7 +230,7 @@ test-system:
 # Primarily intended for CI.
 test-system-local: .eval-skopeo-binary
 	hack/warn-destructive-tests.sh
-	bats --tap systemtest
+	hack/test-system.sh
 
 test-unit:
 	# Just call (make test unit-local) here instead of worrying about environment differences
@@ -265,8 +269,3 @@ vendor:
 
 vendor-in-container:
 	podman run --privileged --rm --env HOME=/root -v $(CURDIR):/src -w /src golang $(MAKE) vendor
-
-# CAUTION: This is not a replacement for RPMs provided by your distro.
-# Only intended to build and test the latest unreleased changes.
-rpm:
-	rpkg local

hack/test-system.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+set -e
+
+# These tests can run in/outside of a container.  However,
+# not all storage drivers are supported in a container
+# environment.  Detect this and setup storage when
+# running in a container.
+#
+# Paradoxically (FIXME: clean this up), SKOPEO_CONTAINER_TESTS is set
+# both inside a container and without a container (in a CI VM); it actually means
+# "it is safe to destructively modify the system for tests".
+#
+# On a CI VM, we can just use Podman as it is already configured; the changes below,
+# to use VFS, are necessary only inside a container, because overlay-inside-overlay
+# does not work. So, make these changes conditional on both
+# SKOPEO_CONTAINER_TESTS (for acceptability to do destructive modification) and !CI
+# (for necessity to adjust for in-container operation)
+if ((SKOPEO_CONTAINER_TESTS)) && [[ "$CI" != true ]]; then
+    if [[ -r /etc/containers/storage.conf ]]; then
+        echo "MODIFYING existing storage.conf"
+        sed -i \
+            -e 's/^driver\s*=.*/driver = "vfs"/' \
+            -e 's/^mountopt/#mountopt/' \
+            /etc/containers/storage.conf
+    else
+        echo "CREATING NEW storage.conf"
+        cat >> /etc/containers/storage.conf << EOF
+[storage]
+driver = "vfs"
+runroot = "/run/containers/storage"
+graphroot = "/var/lib/containers/storage"
+EOF
+    fi
+    # The logic of finding the relevant storage.conf file is convoluted
+    # and in effect differs between Skopeo and Podman, at least in some versions;
+    # explicitly point at the file we want to use to hopefully avoid that.
+    export CONTAINERS_STORAGE_CONF=/etc/containers/storage.conf
+fi
+
+bats --tap systemtest