pkg/destroy/libvirt: Use prefix-based deletion

To avoid wiping out the caller's whole libvirt environment, regardless
of whether it was associated with our cluster or not.  Using
cluster-name prefixes still makes me a bit jumpy, so I've added
warnings to both the environment-variable and asset-prompt docs
warning libvirt users to pick something sufficiently unique.

Also:

* Use {cluster-name}-master-{count} naming.  We used to use
  master{count}, which diverged from other usage (e.g. AWS, which has
  used master-{count} since way back in ca443c5e (openstack/nova:
  replace cloud-init with ignition, 2017-02-27,
  coreos/tectonic-installer#7).

* Rename module.libvirt_base_volume -> module.volume.  There's no
  reason to diverge from the module source for that name.

data/data/libvirt/bootstrap/main.tf

@@ -1,15 +1,15 @@
 resource "libvirt_volume" "bootstrap" {
-  name           = "bootstrap"
+  name           = "${var.cluster_name}-bootstrap"
   base_volume_id = "${var.base_volume_id}"
 }
 
 resource "libvirt_ignition" "bootstrap" {
-  name    = "bootstrap.ign"
+  name    = "${var.cluster_name}-bootstrap.ign"
   content = "${var.ignition}"
 }
 
 resource "libvirt_domain" "bootstrap" {
-  name = "bootstrap"
+  name = "${var.cluster_name}-bootstrap"
 
   memory = "2048"
 

data/data/libvirt/main.tf

@@ -2,17 +2,18 @@ provider "libvirt" {
   uri = "${var.tectonic_libvirt_uri}"
 }
 
-module "libvirt_base_volume" {
+module "volume" {
   source = "./volume"
 
-  image = "${var.tectonic_os_image}"
+  cluster_name = "${var.tectonic_cluster_name}"
+  image        = "${var.tectonic_os_image}"
 }
 
 module "bootstrap" {
   source = "./bootstrap"
 
   addresses      = ["${var.tectonic_libvirt_bootstrap_ip}"]
-  base_volume_id = "${module.libvirt_base_volume.coreos_base_volume_id}"
+  base_volume_id = "${module.volume.coreos_base_volume_id}"
   cluster_name   = "${var.tectonic_cluster_name}"
   ignition       = "${var.ignition_bootstrap}"
   network_id     = "${libvirt_network.tectonic_net.id}"
@@ -20,17 +21,17 @@ module "bootstrap" {
 
 resource "libvirt_volume" "master" {
   count          = "${var.tectonic_master_count}"
-  name           = "master${count.index}"
-  base_volume_id = "${module.libvirt_base_volume.coreos_base_volume_id}"
+  name           = "${var.tectonic_cluster_name}-master-${count.index}"
+  base_volume_id = "${module.volume.coreos_base_volume_id}"
 }
 
 resource "libvirt_ignition" "master" {
-  name    = "master.ign"
+  name    = "${var.tectonic_cluster_name}-master.ign"
   content = "${var.ignition_master}"
 }
 
 resource "libvirt_ignition" "worker" {
-  name    = "worker.ign"
+  name    = "${var.tectonic_cluster_name}-worker.ign"
   content = "${var.ignition_worker}"
 }
 
@@ -67,7 +68,7 @@ resource "libvirt_network" "tectonic_net" {
 resource "libvirt_domain" "master" {
   count = "${var.tectonic_master_count}"
 
-  name = "master${count.index}"
+  name = "${var.tectonic_cluster_name}-master-${count.index}"
 
   memory = "3072"
   vcpu   = "2"

data/data/libvirt/volume/main.tf

@@ -1,4 +1,4 @@
 resource "libvirt_volume" "coreos_base" {
-  name   = "coreos_base"
+  name   = "${var.cluster_name}-base"
   source = "${var.image}"
 }

data/data/libvirt/volume/variables.tf

@@ -1,3 +1,8 @@
+variable "cluster_name" {
+  type        = "string"
+  description = "The name of the cluster."
+}
+
 variable "image" {
   description = "The URL of the OS disk image"
   type        = "string"

docs/user/environment-variables.md

@@ -17,6 +17,9 @@ The installer accepts a number of environment variable that allow the interactiv
 * `OPENSHIFT_INSTALL_CLUSTER_NAME`:
      The name of the cluster.
      This will be used when generating sub-domains.
+
+     For libvirt, choose a name that is unique enough to be used as a prefix during cluster deletion.
+     For example, if you use `demo` as your cluster name, `openshift-install destroy cluster` may destroy all domains, networks, pools, and volumes that begin with `demo`.
 * `OPENSHIFT_INSTALL_EMAIL_ADDRESS`:
      The email address of the cluster administrator.
      This will be used to log in to the console.

pkg/asset/installconfig/clustername.go

@@ -25,7 +25,7 @@ func (a *clusterName) Generate(asset.Parents) error {
 		&survey.Question{
 			Prompt: &survey.Input{
 				Message: "Cluster Name",
-				Help:    "The name of the cluster. This will be used when generating sub-domains.",
+				Help:    "The name of the cluster.  This will be used when generating sub-domains.\n\nFor libvirt, choose a name that is unique enough to be used as a prefix during cluster deletion.  For example, if you use 'demo' as your cluster name, `openshift-install destroy cluster` may destroy all domains, networks, pools, and volumes that begin with 'demo'.",
 			},
 			Validate: survey.ComposeValidators(survey.Required, func(ans interface{}) error {
 				return validate.DomainName(ans.(string))

pkg/asset/machines/libvirt/machines.go

@@ -41,7 +41,7 @@ func Machines(config *types.InstallConfig, pool *types.MachinePool, role, userDa
 			},
 			ObjectMeta: metav1.ObjectMeta{
 				Namespace: "openshift-cluster-api",
-				Name:      fmt.Sprintf("%s%d", pool.Name, idx),
+				Name:      fmt.Sprintf("%s-%s-%d", clustername, pool.Name, idx),
 				Labels: map[string]string{
 					"sigs.k8s.io/cluster-api-cluster":      clustername,
 					"sigs.k8s.io/cluster-api-machine-role": role,
@@ -69,10 +69,10 @@ func provider(clusterName string, platform *libvirt.Platform, name string) *libv
 		},
 		DomainMemory: 2048,
 		DomainVcpu:   2,
-		IgnKey:       fmt.Sprintf("/var/lib/libvirt/images/%s.ign", name),
+		IgnKey:       fmt.Sprintf("/var/lib/libvirt/images/%s-%s.ign", clusterName, name),
 		Volume: &libvirtprovider.Volume{
 			PoolName:     "default",
-			BaseVolumeID: "/var/lib/libvirt/images/coreos_base",
+			BaseVolumeID: fmt.Sprintf("/var/lib/libvirt/images/%s-base", clusterName),
 		},
 		NetworkInterfaceName:    clusterName,
 		NetworkInterfaceAddress: platform.Network.IPRange,

pkg/destroy/libvirt/libvirt.go

@@ -209,7 +209,7 @@ func deleteNetwork(conn *libvirt.Connect, filter filterFunc, logger logrus.Field
 func New(logger logrus.FieldLogger, metadata *types.ClusterMetadata) (destroy.Destroyer, error) {
 	return &ClusterUninstaller{
 		LibvirtURI: metadata.ClusterPlatformMetadata.Libvirt.URI,
-		Filter:     AlwaysTrueFilter(), //TODO: change to ClusterNamePrefixFilter when all resources are prefixed.
+		Filter:     ClusterNamePrefixFilter(metadata.ClusterName),
 		Logger:     logger,
 	}, nil
 }