Added option to share kernel namespaces in libpod and podman

A pause container is added to the pod if the user opts in. The default pause image and command can be overridden. Pause containers are ignored in ps unless the -a option is present. Pod inspect and pod ps show shared namespaces and pause container. A pause container can't be removed with podman rm, and a pod can be removed if it only has a pause container.

Signed-off-by: haircommander <pehunt@redhat.com>

Closes: #1187
Approved by: mheon

1 files changed, 17 insertions, 0 deletions

diff --git a/pkg/spec/parse.go b/pkg/spec/parse.go
index d34e10760..4cdc62de6 100644
--- a/pkg/spec/parse.go
+++ b/pkg/spec/parse.go
@@ -18,12 +18,29 @@ func (w *weightDevice) String() string {
 	return fmt.Sprintf("%s:%d", w.path, w.weight)
 }
 
+// LinuxNS is a struct that contains namespace information
+// It implemented Valid to show it is a valid namespace
+type LinuxNS interface {
+	Valid() bool
+}
+
 // IsNS returns if the specified string has a ns: prefix
 func IsNS(s string) bool {
 	parts := strings.SplitN(s, ":", 2)
 	return len(parts) > 1 && parts[0] == "ns"
 }
 
+// IsPod returns if the specified string is pod
+func IsPod(s string) bool {
+	return s == "pod"
+}
+
+// Valid checks the validity of a linux namespace
+// s should be the string representation of ns
+func Valid(s string, ns LinuxNS) bool {
+	return IsPod(s) || IsNS(s) || ns.Valid()
+}
+
 // NS is the path to the namespace to join.
 func NS(s string) string {
 	parts := strings.SplitN(s, ":", 2)