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

3 files changed, 40 insertions, 0 deletions

diff --git a/pkg/spec/createconfig.go b/pkg/spec/createconfig.go
index 6df6fb480..dd1cd5833 100644
--- a/pkg/spec/createconfig.go
+++ b/pkg/spec/createconfig.go
@@ -364,6 +364,9 @@ func (c *CreateConfig) GetContainerCreateOptions(runtime *libpod.Runtime) ([]lib
 
 	networks := make([]string, 0)
 	userNetworks := c.NetMode.UserDefined()
+	if IsPod(userNetworks) {
+		userNetworks = ""
+	}
 	if userNetworks != "" {
 		for _, netName := range strings.Split(userNetworks, ",") {
 			if netName == "" {
@@ -381,6 +384,8 @@ func (c *CreateConfig) GetContainerCreateOptions(runtime *libpod.Runtime) ([]lib
 			return nil, errors.Wrapf(err, "container %q not found", c.NetMode.ConnectedContainer())
 		}
 		options = append(options, libpod.WithNetNSFrom(connectedCtr))
+	} else if IsPod(string(c.NetMode)) {
+		options = append(options, libpod.WithNetNSFromPod())
 	} else if !c.NetMode.IsHost() && !c.NetMode.IsNone() {
 		isRootless := rootless.IsRootless()
 		postConfigureNetNS := isRootless || (len(c.IDMappings.UIDMap) > 0 || len(c.IDMappings.GIDMap) > 0) && !c.UsernsMode.IsHost()
@@ -398,6 +403,10 @@ func (c *CreateConfig) GetContainerCreateOptions(runtime *libpod.Runtime) ([]lib
 
 		options = append(options, libpod.WithPIDNSFrom(connectedCtr))
 	}
+	if IsPod(string(c.PidMode)) {
+		options = append(options, libpod.WithPIDNSFromPod())
+	}
+
 	if c.IpcMode.IsContainer() {
 		connectedCtr, err := c.Runtime.LookupContainer(c.IpcMode.Container())
 		if err != nil {
@@ -406,7 +415,15 @@ func (c *CreateConfig) GetContainerCreateOptions(runtime *libpod.Runtime) ([]lib
 
 		options = append(options, libpod.WithIPCNSFrom(connectedCtr))
 	}
+	if IsPod(string(c.IpcMode)) {
+		options = append(options, libpod.WithIPCNSFromPod())
+	}
+
+	if IsPod(string(c.UtsMode)) {
+		options = append(options, libpod.WithUTSNSFromPod())
+	}
 
+	// TODO: MNT, USER, CGROUP
 	options = append(options, libpod.WithStopSignal(c.StopSignal))
 	options = append(options, libpod.WithStopTimeout(c.StopTimeout))
 	if len(c.DNSSearch) > 0 {
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)
diff --git a/pkg/spec/spec.go b/pkg/spec/spec.go
index 7323b2d2b..8d8a07a2e 100644
--- a/pkg/spec/spec.go
+++ b/pkg/spec/spec.go
@@ -349,6 +349,9 @@ func addPidNS(config *CreateConfig, g *generate.Generator) error {
 	if pidMode.IsContainer() {
 		logrus.Debug("using container pidmode")
 	}
+	if IsPod(string(pidMode)) {
+		logrus.Debug("using pod pidmode")
+	}
 	return nil
 }
 
@@ -384,6 +387,9 @@ func addNetNS(config *CreateConfig, g *generate.Generator) error {
 	} else if IsNS(string(netMode)) {
 		logrus.Debug("Using ns netmode")
 		return g.AddOrReplaceLinuxNamespace(spec.NetworkNamespace, NS(string(netMode)))
+	} else if IsPod(string(netMode)) {
+		logrus.Debug("Using pod netmode, unless pod is not sharing")
+		return nil
 	} else if netMode.IsUserDefined() {
 		logrus.Debug("Using user defined netmode")
 		return nil