Able to specifiy size when using backing volume (and able to resize partitions with cloud-init)

examples/resize_base/.gitignore

@@ -0,0 +1,4 @@
+*.img
+*.qcow2
+*.tfstate*
+.terraform

examples/resize_base/README.md

@@ -0,0 +1,11 @@
+
+This example takes a base image of 2G and uses it as the backing store of a bigger volume. _cloud-init_ is then used to resize the original partition to the new available space.
+
+See https://github.com/dmacvicar/terraform-provider-libvirt/issues/369
+
+# Running
+
+```console
+$ terraform apply
+$ ssh -i id_rsa "root@$(terraform output ip)"
+```

examples/resize_base/id_rsa

@@ -0,0 +1,27 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----

examples/resize_base/id_rsa.pub

@@ -0,0 +1 @@
+ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDMqwoGGtvOrlSvzS0MTa3l+wCQnmoeebnDS/1wRUqSQ+B5ROL5WzCgEAUyN/WdMpsZkASxdLyemEPhdRF3O1X6nWbteinNLW4LQMPI+blPFam0xJ1kBLYMDSXR57K8qY0a94opyuAUCPAwQ2vezKPB80pqjnBphKQsG++CnqhaQ8kbtEpIRHrP+fUkGEmgbAC7ymU2wtZGGGhisYxpVOw5xiPaiEU0zdzn1RqvAs+wqVXZNEk8WkuQabr0FgxHZ/EfIUufWIQy/LbVfTByzhuHZIsHypO7W4OSjoyd4ACUVCA+C8lwhhaGB3IiLRUaFq288UfgTQLbB8AOpXe6zmrP [email protected]

examples/resize_base/main.tf

@@ -0,0 +1,76 @@
+provider "libvirt" {
+  uri = "qemu:///system"
+}
+
+resource "libvirt_volume" "os_image_ubuntu" {
+  name = "os_image_ubuntu"
+  pool = "default"
+  source = "https://cloud-images.ubuntu.com/releases/xenial/release/ubuntu-16.04-server-cloudimg-amd64-disk1.img"
+}
+
+resource "libvirt_volume" "disk_ubuntu_resized" {
+  name = "disk"
+  base_volume_id = "${libvirt_volume.os_image_ubuntu.id}"
+  pool = "default"
+  size = 5361393152
+}
+
+# Use CloudInit to add our ssh-key to the instance
+resource "libvirt_cloudinit_disk" "cloudinit_ubuntu_resized" {
+  name           = "cloudinit_ubuntu_resized.iso"
+  pool = "default"
+  user_data = <<EOF
+#cloud-config
+disable_root: 0
+ssh_pwauth: 1
+users:
+  - name: root
+    ssh-authorized-keys:
+      - ${file("id_rsa.pub")}
+growpart:
+  mode: auto
+  devices: ['/']
+EOF
+}
+
+resource "libvirt_domain" "domain_ubuntu_resized" {
+  name = "doman_ubuntu_resized"
+  memory = "512"
+  vcpu = 1
+
+  cloudinit = "${libvirt_cloudinit_disk.cloudinit_ubuntu_resized.id}"
+
+  network_interface {
+    network_name = "default"
+    wait_for_lease = true
+  }
+
+  # IMPORTANT
+  # Ubuntu can hang if an isa-serial is not present at boot time.
+  # If you find your CPU 100% and never is available this is why
+  console {
+    type        = "pty"
+    target_port = "0"
+    target_type = "serial"
+  }
+
+  console {
+      type        = "pty"
+      target_type = "virtio"
+      target_port = "1"
+  }
+
+  disk {
+       volume_id = "${libvirt_volume.disk_ubuntu_resized.id}"
+  }
+
+  graphics {
+    type = "spice"
+    listen_type = "address"
+    autoport = true
+  }
+}
+
+output "ip" {
+  value = "${libvirt_domain.domain_ubuntu_resized.network_interface.0.addresses.0}"
+}

libvirt/resource_libvirt_volume.go

@@ -102,8 +102,7 @@ func resourceLibvirtVolumeCreate(d *schema.ResourceData, meta interface{}) error
 	volumeDef.Name = d.Get("name").(string)
 
 	var (
-		img    image
-		volume *libvirt.StorageVol
+		img image
 	)
 
 	givenFormat, isFormatGiven := d.GetOk("format")
@@ -151,76 +150,73 @@ func resourceLibvirtVolumeCreate(d *schema.ResourceData, meta interface{}) error
 		volumeDef.Capacity.Unit = "B"
 		volumeDef.Capacity.Value = size
 	} else {
-		_, noSize := d.GetOk("size")
-		_, noBaseVol := d.GetOk("base_volume_id")
 
-		if noSize && noBaseVol {
-			return fmt.Errorf("'size' needs to be specified if no 'source' or 'base_volume_id' is given")
-		}
-		volumeDef.Capacity.Value = uint64(d.Get("size").(int))
-	}
-
-	if baseVolumeID, ok := d.GetOk("base_volume_id"); ok {
-		if _, ok := d.GetOk("size"); ok {
-			return fmt.Errorf("'size' can't be specified when also 'base_volume_id' is given (the size will be set to the size of the backing image")
-		}
+		// the volume does not have a source image to upload, first handle
+		// whether it has a backing image
+		//
+		// backing images can be specified by either (id), or by (name, pool)
+		var baseVolume *libvirt.StorageVol
 
-		if _, ok := d.GetOk("base_volume_name"); ok {
-			return fmt.Errorf("'base_volume_name' can't be specified when also 'base_volume_id' is given")
-		}
-
-		volume = nil
-		baseVolume, err := client.libvirt.LookupStorageVolByKey(baseVolumeID.(string))
-		if err != nil {
-			return fmt.Errorf("Can't retrieve volume %s: %v", baseVolumeID.(string), err)
-		}
-		backingStoreDef, err := newDefBackingStoreFromLibvirt(baseVolume)
-		if err != nil {
-			return fmt.Errorf("Could not retrieve backing store %s", baseVolumeID.(string))
+		if baseVolumeID, ok := d.GetOk("base_volume_id"); ok {
+			if _, ok := d.GetOk("base_volume_name"); ok {
+				return fmt.Errorf("'base_volume_name' can't be specified when also 'base_volume_id' is given")
+			}
+			baseVolume, err = client.libvirt.LookupStorageVolByKey(baseVolumeID.(string))
+			if err != nil {
+				return fmt.Errorf("Can't retrieve volume %s: %v", baseVolumeID.(string), err)
+			}
 		}
-		volumeDef.BackingStore = &backingStoreDef
-	}
 
-	if baseVolumeName, ok := d.GetOk("base_volume_name"); ok {
-		if _, ok := d.GetOk("size"); ok {
-			return fmt.Errorf("'size' can't be specified when also 'base_volume_name' is given (the size will be set to the size of the backing image")
+		if baseVolumeName, ok := d.GetOk("base_volume_name"); ok {
+			baseVolumePool := pool
+			if _, ok := d.GetOk("base_volume_pool"); ok {
+				baseVolumePoolName := d.Get("base_volume_pool").(string)
+				baseVolumePool, err = client.libvirt.LookupStoragePoolByName(baseVolumePoolName)
+				if err != nil {
+					return fmt.Errorf("can't find storage pool '%s'", baseVolumePoolName)
+				}
+				defer baseVolumePool.Free()
+			}
+			baseVolume, err = baseVolumePool.LookupStorageVolByName(baseVolumeName.(string))
+			if err != nil {
+				return fmt.Errorf("Can't retrieve volume %s: %v", baseVolumeName.(string), err)
+			}
 		}
 
-		volume = nil
-		baseVolumePool := pool
-		if _, ok := d.GetOk("base_volume_pool"); ok {
-			baseVolumePoolName := d.Get("base_volume_pool").(string)
-			baseVolumePool, err = client.libvirt.LookupStoragePoolByName(baseVolumePoolName)
+		if baseVolume != nil {
+			backingStoreDef, err := newDefBackingStoreFromLibvirt(baseVolume)
 			if err != nil {
-				return fmt.Errorf("can't find storage pool '%s'", baseVolumePoolName)
+				return fmt.Errorf("Could not retrieve backing store definition: %s", err.Error())
 			}
-			defer baseVolumePool.Free()
-		}
-		baseVolume, err := baseVolumePool.LookupStorageVolByName(baseVolumeName.(string))
-		if err != nil {
-			return fmt.Errorf("Can't retrieve volume %s: %v", baseVolumeName.(string), err)
-		}
-		backingStoreDef, err := newDefBackingStoreFromLibvirt(baseVolume)
-		if err != nil {
-			return fmt.Errorf("Could not retrieve backing store %s", baseVolumeName.(string))
+
+			// does the backing store have some size information?, check at least that it is not smaller than the backing store
+			volumeDef.Capacity.Value = uint64(d.Get("size").(int))
+			if _, ok := d.GetOk("size"); ok {
+				backingStoreVolumeDef, err := newDefVolumeFromLibvirt(baseVolume)
+				if err != nil {
+					return err
+				}
+
+				if backingStoreVolumeDef.Capacity != nil && volumeDef.Capacity.Value < backingStoreVolumeDef.Capacity.Value {
+					return fmt.Errorf("When 'size' is specified, it shouldn't be smaller than the backing store specified with 'base_volume_id' or 'base_volume_name/base_volume_pool'")
+				}
+			}
+			volumeDef.BackingStore = &backingStoreDef
 		}
-		volumeDef.BackingStore = &backingStoreDef
 	}
 
-	if volume == nil {
-		volumeDefXML, err := xml.Marshal(volumeDef)
-		if err != nil {
-			return fmt.Errorf("Error serializing libvirt volume: %s", err)
-		}
+	volumeDef.Capacity.Value = uint64(d.Get("size").(int))
+	volumeDefXML, err := xml.Marshal(volumeDef)
+	if err != nil {
+		return fmt.Errorf("Error serializing libvirt volume: %s", err)
+	}
 
-		// create the volume
-		v, err := pool.StorageVolCreateXML(string(volumeDefXML), 0)
-		if err != nil {
-			return fmt.Errorf("Error creating libvirt volume: %s", err)
-		}
-		volume = v
-		defer volume.Free()
+	// create the volume
+	volume, err := pool.StorageVolCreateXML(string(volumeDefXML), 0)
+	if err != nil {
+		return fmt.Errorf("Error creating libvirt volume: %s", err)
 	}
+	defer volume.Free()
 
 	// we use the key as the id
 	key, err := volume.GetKey()

website/docs/r/volume.html.markdown

@@ -55,6 +55,9 @@ The following arguments are supported:
 * `size` - (Optional) The size of the volume in bytes (if you don't like this,
   help fix [this issue](https://github.com/hashicorp/terraform/issues/3287).
   If `source` is specified, `size` will be set to the source image file size.
+  `size` can be omitted if `source` is specified. `size` will then be set to the source image file size.
+  `size` can be omitted if `base_volume_id` or `base_volume_name` is specified. `size` will then be set to the base volume size.
+  If `size` is specified to be bigger than `base_volume_id` or `base_volume_name` size, you can use [cloudinit](https://cloudinit.readthedocs.io) if your OS supports it, with `libvirt_cloudinit_disk` and the [growpart](https://cloudinit.readthedocs.io/en/latest/topics/modules.html#growpart) module to resize the partition.
 * `base_volume_id` - (Optional) The backing volume (CoW) to use for this volume.
 * `base_volume_name` - (Optional) The name of the backing volume (CoW) to use
   for this volume. Note well: when `base_volume_pool` is not specified the