libnetwork/netavark: do not create config dir in init

Podman creates/initializes the network backend for every command. Howver
most commands will not need it so we should keep the required actions we
do to a minimum.

In this case the config directory /etc/containers/networks by default as
root may not exists and then we try to create it which can fail, i.e.
when /etc is read only[1].

The code here are a bit more changes then I would have liked but we must
make sure the default in memory network always exists and do not create
the directory there.

[1] containers#2265

Signed-off-by: Paul Holzinger <[email protected]>

libnetwork/netavark/config.go

@@ -30,6 +30,9 @@ func sliceRemoveDuplicates(strList []string) []string {
 }
 
 func (n *netavarkNetwork) commitNetwork(network *types.Network) error {
+	if err := os.MkdirAll(n.networkConfigDir, 0o755); err != nil {
+		return nil
+	}
 	confPath := filepath.Join(n.networkConfigDir, network.Name+".json")
 	f, err := os.Create(confPath)
 	if err != nil {

libnetwork/netavark/network.go

@@ -139,10 +139,6 @@ func NewNetworkInterface(conf *InitConfig) (types.ContainerNetwork, error) {
 		return nil, err
 	}
 
-	if err := os.MkdirAll(conf.NetworkRunDir, 0o755); err != nil {
-		return nil, err
-	}
-
 	defaultSubnetPools := conf.Config.Network.DefaultSubnetPools
 	if defaultSubnetPools == nil {
 		defaultSubnetPools = config.DefaultSubnetPools
@@ -187,6 +183,21 @@ func (n *netavarkNetwork) loadNetworks() error {
 	// check the mod time of the config dir
 	f, err := os.Stat(n.networkConfigDir)
 	if err != nil {
+		// the directory may not exists which is fine. It will be created on the first network create
+		if errors.Is(err, os.ErrNotExist) {
+			// networks are already loaded
+			if n.networks != nil {
+				return nil
+			}
+			networks := make(map[string]*types.Network, 1)
+			networkInfo, err := n.createDefaultNetwork()
+			if err != nil {
+				return fmt.Errorf("failed to create default network %s: %w", n.defaultNetwork, err)
+			}
+			networks[n.defaultNetwork] = networkInfo
+			n.networks = networks
+			return nil
+		}
 		return err
 	}
 	modTime := f.ModTime()