implement init containers in podman

this is the first pass at implementing init containers for podman pods.
init containersare made popular by k8s as a way to run setup for pods
before the pods standard containers run.

unlike k8s, we support two styles of init containers: always and
oneshot.  always means the container stays in the pod and starts
whenever a pod is started.  this does not apply to pods restarting.
oneshot means the container runs onetime when the pod starts and then is
removed.

Signed-off-by: Brent Baude <bbaude@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/libpod/container_validate.go b/libpod/container_validate.go
index 6ff46f1b1..91ebe93fb 100644
--- a/libpod/container_validate.go
+++ b/libpod/container_validate.go
@@ -131,5 +131,11 @@ func (c *Container) validate() error {
 	if c.config.User == "" && (c.config.Spec.Process.User.UID != 0 || c.config.Spec.Process.User.GID != 0) {
 		return errors.Wrapf(define.ErrInvalidArg, "please set User explicitly via WithUser() instead of in OCI spec directly")
 	}
+
+	// Init-ctrs must be used inside a Pod.  Check if a init container type is
+	// passed and if no pod is passed
+	if len(c.config.InitContainerType) > 0 && len(c.config.Pod) < 1 {
+		return errors.Wrap(define.ErrInvalidArg, "init containers must be created in a pod")
+	}
 	return nil
 }