Add the option of Rootless CNI networking by default

When the containers.conf field "NetNS" is set to "Bridge" and the
"RootlessNetworking" field is set to "cni", Podman will now
handle rootless in the same way it does root - all containers
will be joined to a default CNI network, instead of exclusively
using slirp4netns.

If no CNI default network config is present for the user, one
will be auto-generated (this also works for root, but it won't be
nearly as common there since the package should already ship a
config).

I eventually hope to remove the "NetNS=Bridge" bit from
containers.conf, but let's get something in for Brent to work
with.

Signed-off-by: Matthew Heon <mheon@redhat.com>

2 files changed, 7 insertions, 3 deletions

diff --git a/pkg/specgen/generate/namespaces.go b/pkg/specgen/generate/namespaces.go
index 278f35c22..f41186ae4 100644
--- a/pkg/specgen/generate/namespaces.go
+++ b/pkg/specgen/generate/namespaces.go
@@ -66,7 +66,7 @@ func GetDefaultNamespaceMode(nsType string, cfg *config.Config, pod *libpod.Pod)
 	case "cgroup":
 		return specgen.ParseCgroupNamespace(cfg.Containers.CgroupNS)
 	case "net":
-		ns, _, err := specgen.ParseNetworkNamespace(cfg.Containers.NetNS)
+		ns, _, err := specgen.ParseNetworkNamespace(cfg.Containers.NetNS, cfg.Containers.RootlessNetworking == "cni")
 		return ns, err
 	}
 
diff --git a/pkg/specgen/namespaces.go b/pkg/specgen/namespaces.go
index f665fc0be..80852930a 100644
--- a/pkg/specgen/namespaces.go
+++ b/pkg/specgen/namespaces.go
@@ -253,7 +253,7 @@ func ParseUserNamespace(ns string) (Namespace, error) {
 // ParseNetworkNamespace parses a network namespace specification in string
 // form.
 // Returns a namespace and (optionally) a list of CNI networks to join.
-func ParseNetworkNamespace(ns string) (Namespace, []string, error) {
+func ParseNetworkNamespace(ns string, rootlessDefaultCNI bool) (Namespace, []string, error) {
 	toReturn := Namespace{}
 	var cniNetworks []string
 	// Net defaults to Slirp on rootless
@@ -264,7 +264,11 @@ func ParseNetworkNamespace(ns string) (Namespace, []string, error) {
 		toReturn.NSMode = FromPod
 	case ns == "" || ns == string(Default) || ns == string(Private):
 		if rootless.IsRootless() {
-			toReturn.NSMode = Slirp
+			if rootlessDefaultCNI {
+				toReturn.NSMode = Bridge
+			} else {
+				toReturn.NSMode = Slirp
+			}
 		} else {
 			toReturn.NSMode = Bridge
 		}