move network alias validation to container create

Podman 4.0 currently errors when you use network aliases for a network which
has dns disabled. Because the error happens on network setup this can
cause regression for old working containers. The network backend should not
validate this. Instead podman should check this at container create time
and also for network connect.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/libpod/networking_linux.go b/libpod/networking_linux.go
index e4fcfc271..e792a410c 100644
--- a/libpod/networking_linux.go
+++ b/libpod/networking_linux.go
@@ -1262,6 +1262,14 @@ func (c *Container) NetworkConnect(nameOrID, netName string, aliases []string) e
 	// get network status before we connect
 	networkStatus := c.getNetworkStatus()
 
+	network, err := c.runtime.network.NetworkInspect(netName)
+	if err != nil {
+		return err
+	}
+	if !network.DNSEnabled && len(aliases) > 0 {
+		return errors.Wrapf(define.ErrInvalidArg, "cannot set network aliases for network %q because dns is disabled", netName)
+	}
+
 	if err := c.runtime.state.NetworkConnect(c, netName, aliases); err != nil {
 		return err
 	}