Add `systemd` build tag

If the systemd development files are not present on the system which
builds podman, then `podman events` will error on runtime creation.
Beside this, a warning will be printed when compiling podman.

This commit mainly exists because projects which depend on libpod
would not need the podman event support and therefore do not need to
rely on the systemd headers.

Signed-off-by: Sascha Grunert <sgrunert@suse.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/libpod/events/journal_unsupported.go b/libpod/events/journal_unsupported.go
new file mode 100644
index 000000000..c91d81f12
--- /dev/null
+++ b/libpod/events/journal_unsupported.go
@@ -0,0 +1,8 @@
+// +build !systemd
+
+package events
+
+// newEventJournalD always returns an error if libsystemd not found
+func newEventJournalD(options EventerOptions) (Eventer, error) {
+	return nil, ErrNoJournaldLogging
+}