CI: enable sqlite system tests

In setup, write a containers.conf.d file with db_backend
as specified in .cirrus.yml.

This is actually much scarier and more achy-breaky than
merely "sqlite system tests": it enables sqlite in e2e
tests. ("But wait, we already do that!" -- no, not really.
sqlite in e2e is being done via --db-backend option, and
some podman commands in e2e do not use the standard options.
See #17904.

This is unlikely to get merged any time soon (March, maybe
even April) because sqlite is still too fragile; this will
trigger more flakes than are currently acceptable. Also,
the nasty auto-update flake seems to trigger much more
reliably with sqlite. We need that one fixed.

Signed-off-by: Ed Santiago <[email protected]>

contrib/cirrus/setup_environment.sh

@@ -75,6 +75,8 @@ fi
 
 cd "${GOSRC}/"
 
+mkdir -p /etc/containers/containers.conf.d
+
 # Defined by lib.sh: Does the host support cgroups v1 or v2? Use runc or crun
 # respectively.
 # **IMPORTANT**: $OCI_RUNTIME is a fakeout! It is used only in e2e tests.
@@ -84,7 +86,7 @@ case "$CG_FS_TYPE" in
         if ((CONTAINER==0)); then
             warn "Forcing testing with runc instead of crun"
             echo "OCI_RUNTIME=runc" >> /etc/ci_environment
-            printf "[engine]\nruntime=\"runc\"\n" >>/etc/containers/containers.conf
+            printf "[engine]\nruntime=\"runc\"\n" > /etc/containers/containers.conf.d/90-runtime.conf
         fi
         ;;
     cgroup2fs)
@@ -93,6 +95,10 @@ case "$CG_FS_TYPE" in
     *) die_unknown CG_FS_TYPE
 esac
 
+# Force the requested database backend without having to use command-line args
+# shellcheck disable=SC2154
+printf "[engine]\ndatabase_backend=\"$CI_DESIRED_DATABASE\"\n" > /etc/containers/containers.conf.d/92-db.conf
+
 if ((CONTAINER==0)); then  # Not yet running inside a container
     # Discovered reemergence of BFQ scheduler bug in kernel 5.8.12-200
     # which causes a kernel panic when system is under heavy I/O load.

test/system/005-info.bats

@@ -94,7 +94,6 @@ host.slirp4netns.executable | $expr_path
 }
 
 @test "podman info - confirm desired database" {
-    skip "FIXME: no way yet (2023-03-16) to override DB in system tests"
     if [[ -z "$CI_DESIRED_DATABASE" ]]; then
         # When running in Cirrus, CI_DESIRED_DATABASE *must* be defined
         # in .cirrus.yml so we can double-check that all CI VMs are