// getClusterUID returns the cluster UID. Rules for UID generation:
// If the user specifies a --cluster-uid param it overwrites everything
// else, check UID config map for a previously recorded uid
// else, check if there are any working Ingresses
// - remember that "" is the cluster uid
// else, allocate a new uid
func getClusterUID(kubeClient *client.Client, name string) (string, error) {
cfgVault := storage.NewConfigMapVault(kubeClient, api.NamespaceSystem, uidConfigMapName)
if name != "" {
glog.Infof("Using user provided cluster uid %v", name)
// Don't save the uid in the vault, so users can rollback through
// --cluster-uid=""
return name, nil
}
existingUID, found, err := cfgVault.Get()
if found {
glog.Infof("Using saved cluster uid %q", existingUID)
return existingUID, nil
} else if err != nil {
// This can fail because of:
// 1. No such config map - found=false, err=nil
// 2. No such key in config map - found=false, err=nil
// 3. Apiserver flake - found=false, err!=nil
// It is not safe to proceed in 3.
return "", fmt.Errorf("Failed to retrieve current uid: %v, using %q as name", err, name)
}
// Check if the cluster has an Ingress with ip
ings, err := kubeClient.Extensions().Ingress(api.NamespaceAll).List(api.ListOptions{LabelSelector: labels.Everything()})
if err != nil {
return "", err
}
namer := utils.Namer{}
for _, ing := range ings.Items {
if len(ing.Status.LoadBalancer.Ingress) != 0 {
c := namer.ParseName(loadbalancers.GCEResourceName(ing.Annotations, "forwarding-rule"))
if c.ClusterName != "" {
return c.ClusterName, cfgVault.Put(c.ClusterName)
}
glog.Infof("Found a working Ingress, assuming uid is empty string")
return "", cfgVault.Put("")
}
}
// Allocate new uid
f, err := os.Open("/dev/urandom")
if err != nil {
return "", err
}
defer f.Close()
b := make([]byte, 8)
if _, err := f.Read(b); err != nil {
return "", err
}
uid := fmt.Sprintf("%x", b)
return uid, cfgVault.Put(uid)
}
