system tests: enable sdnotify tests

Oops. PR #6693 (sdnotify) added tests, but they were disabled
due to broken crun on f31. I tried for three weeks to get a
magic CI:IMG PR to update crun on the CI VMs ... but in that
time I forgot to actually enable those new tests.

This PR removes a 'skip', replacing it with a check that systemd
is running plus one more to make sure our runtime is crun. It
looks like sdnotify just doesn't work on Ubuntu (it hangs), and
my guess is that it's a crun/runc issue.

I also changed the test image from fedora:latest to :31, because,
sigh, fedora:latest removed the systemd-notify tool.

WARNING WARNING WARNING: the symptom of a missing systemd-notify
is that podman will hang forever, not even stopped by the timeout
command in podman_run! (Filed: #7316). This means that if the
sdnotify-in-container test ever fails, the symptom will be that
Cirrus itself will time out (2 hours?). This is horrible. I
don't know what to do about it other than push for a fix for 7316.

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

test/system/260-sdnotify.bats

@@ -12,8 +12,15 @@ _SOCAT_LOG=
 function setup() {
     skip_if_remote
 
-    # TODO: remove this once CI systems have newer crun and container-selinux
-    skip "TEMPORARY SKIP - until CI systems get new crun, container-selinux"
+    # Skip if systemd is not running
+    systemctl list-units &>/dev/null || skip "systemd not available"
+
+    # sdnotify fails with runc 1.0.0-3-dev2 on Ubuntu. Let's just
+    # assume that we work only with crun, nothing else.
+    run_podman info --format '{{ .Host.OCIRuntime.Name }}'
+    if [[ "$output" != "crun" ]]; then
+        skip "this test only works with crun, not '$output'"
+    fi
 
     basic_setup
 }
@@ -107,7 +114,7 @@ function _assert_mainpid_is_conmon() {
 @test "sdnotify : container" {
     # Sigh... we need to pull a humongous image because it has systemd-notify.
     # FIXME: is there a smaller image we could use?
-    _FEDORA=registry.fedoraproject.org/fedora:latest
+    _FEDORA=registry.fedoraproject.org/fedora:31
 
     # Pull that image. Retry in case of flakes.
     run_podman pull $_FEDORA || \