pod: add exit policies

Add the notion of an "exit policy" to a pod.  This policy controls the
behaviour when the last container of pod exits.  Initially, there are
two policies:

 - "continue" : the pod continues running. This is the default policy
                when creating a pod.

 - "stop" : stop the pod when the last container exits. This is the
            default behaviour for `play kube`.

In order to implement the deferred stop of a pod, add a worker queue to
the libpod runtime.  The queue will pick up work items and in this case
helps resolve dead locks that would otherwise occur if we attempted to
stop a pod during container cleanup.

Note that the default restart policy of `play kube` is "Always".  Hence,
in order to really solve #13464, the YAML files must set a custom
restart policy; the tests use "OnFailure".

Fixes: #13464
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/libpod/runtime.go b/libpod/runtime.go
index 6c2323d88..d5daa2f8a 100644
--- a/libpod/runtime.go
+++ b/libpod/runtime.go
@@ -86,6 +86,10 @@ type Runtime struct {
 	libimageEventsShutdown chan bool
 	lockManager            lock.Manager
 
+	// Worker
+	workerShutdown chan bool
+	workerChannel  chan func()
+
 	// syslog describes whenever logrus should log to the syslog as well.
 	// Note that the syslog hook will be enabled early in cmd/podman/syslog_linux.go
 	// This bool is just needed so that we can set it for netavark interface.
@@ -597,6 +601,8 @@ func makeRuntime(runtime *Runtime) (retErr error) {
 		}
 	}
 
+	runtime.startWorker()
+
 	// Mark the runtime as valid - ready to be used, cannot be modified
 	// further
 	runtime.valid = true
@@ -817,6 +823,14 @@ func (r *Runtime) Shutdown(force bool) error {
 		return define.ErrRuntimeStopped
 	}
 
+	if r.workerShutdown != nil {
+		// Signal the worker routine to shutdown.  The routine will
+		// process all pending work items and then read from the
+		// channel; we're blocked until all work items have been
+		// processed.
+		r.workerShutdown <- true
+	}
+
 	r.valid = false
 
 	// Shutdown all containers if --force is given