Write Ignition file as a volume in a libvirt storage pool

This avoids the problem where the Ignition file is remote to
the host on which the libvirt domain is being created.  We've
added a "libvirt_ignition" resource which manages the Ignition
file in the libvirt volume - creates it, and destroys it.  The
"coreos_ignition" field in the libvirt_domain definition must
point to the Id of a "libvirt_ignition" resource.

The code is modelled on that used for CloudInit.

1 files changed, 202 insertions, 0 deletions

diff --git a/libvirt/coreos_ignition_def.go b/libvirt/coreos_ignition_def.go
new file mode 100644
index 00000000..216075f2
--- /dev/null
+++ b/libvirt/coreos_ignition_def.go
@@ -0,0 +1,202 @@
+package libvirt
+
+import (
+	"encoding/xml"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"strings"
+
+	libvirt "github.com/dmacvicar/libvirt-go"
+	"github.com/mitchellh/packer/common/uuid"
+)
+
+type defIgnition struct {
+	Name            string
+	PoolName        string
+	Content 	string
+}
+
+// Creates a new cloudinit with the defaults
+// the provider uses
+func newIgnitionDef() defIgnition {
+	ign := defIgnition{}
+
+	return ign
+}
+
+// Create a ISO file based on the contents of the CloudInit instance and
+// uploads it to the libVirt pool
+// Returns a string holding terraform's internal ID of this resource
+func (ign *defIgnition) CreateAndUpload(virConn *libvirt.VirConnection) (string, error) {
+	pool, err := virConn.LookupStoragePoolByName(ign.PoolName)
+	if err != nil {
+		return "", fmt.Errorf("can't find storage pool '%s'", ign.PoolName)
+	}
+	defer pool.Free()
+
+	PoolSync.AcquireLock(ign.PoolName)
+	defer PoolSync.ReleaseLock(ign.PoolName)
+
+	// Refresh the pool of the volume so that libvirt knows it is
+	// not longer in use.
+	WaitForSuccess("Error refreshing pool for volume", func() error {
+		return pool.Refresh(0)
+	})
+
+	volumeDef := newDefVolume()
+	volumeDef.Name = ign.Name
+
+	ignFile, err := ign.createFile()
+	if err != nil {
+		return "", err
+	}
+	defer func() {
+		// Remove the tmp ignition file
+		if err = os.Remove(ignFile); err != nil {
+			log.Printf("Error while removing tmp Ignition file: %s", err)
+		}
+	}()
+
+	img, err := newImage(ignFile)
+	if err != nil {
+		return "", err
+	}
+
+	size, err := img.Size()
+	if err != nil {
+		return "", err
+	}
+
+	volumeDef.Capacity.Unit = "B"
+	volumeDef.Capacity.Amount = size
+	volumeDef.Target.Format.Type = "raw"
+
+	volumeDefXml, err := xml.Marshal(volumeDef)
+	if err != nil {
+		return "", fmt.Errorf("Error serializing libvirt volume: %s", err)
+	}
+
+	// create the volume
+	volume, err := pool.StorageVolCreateXML(string(volumeDefXml), 0)
+	if err != nil {
+		return "", fmt.Errorf("Error creating libvirt volume for Ignition %s: %s", ign.Name, err)
+	}
+	defer volume.Free()
+
+	// upload ignition file
+	stream, err := libvirt.NewVirStream(virConn, 0)
+	if err != nil {
+		return "", err
+	}
+	defer stream.Close()
+
+	volume.Upload(stream, 0, uint64(volumeDef.Capacity.Amount), 0)
+	err = img.WriteToStream(stream)
+	if err != nil {
+		return "", err
+	}
+
+	key, err := volume.GetKey()
+	if err != nil {
+		return "", fmt.Errorf("Error retrieving volume key: %s", err)
+	}
+
+	return ign.buildTerraformKey(key), nil
+}
+
+// create a unique ID for terraform use
+// The ID is made by the volume ID (the internal one used by libvirt)
+// joined by the ";" with a UUID
+func (ign *defIgnition) buildTerraformKey(volumeKey string) string {
+	return fmt.Sprintf("%s;%s", volumeKey, uuid.TimeOrderedUUID())
+}
+
+func getIgnitionVolumeKeyFromTerraformID(id string) (string, error) {
+	s := strings.SplitN(id, ";", 2)
+	if len(s) != 2 {
+		return "", fmt.Errorf("%s is not a valid key", id)
+	}
+	return s[0], nil
+}
+
+
+// Dumps the Ignition object - either generated by Terraform or supplied as a file -
+// to a temporary ignition file
+func (ign *defIgnition) createFile() (string, error) {
+	log.Print("Creating Ignition temporary file")
+	tempFile, err := ioutil.TempFile("", ign.Name)
+	if err != nil {
+		return "", fmt.Errorf("Cannot create tmp file for Ignition: %s",
+			err)
+	}
+	defer tempFile.Close()
+
+	var file bool
+	file = true
+	if _, err := os.Stat(ign.Content); err != nil {
+		var js map[string]interface{}
+		if err_conf := json.Unmarshal([]byte(ign.Content), &js); err_conf != nil {
+			return "", fmt.Errorf("coreos_ignition 'content' is neither a file "+
+				"nor a valid json object %s", ign.Content)
+		}
+		file = false
+	}
+
+	if !file {
+		if _, err := tempFile.WriteString(ign.Content); err != nil {
+			return "", fmt.Errorf("Cannot write Ignition object to temporary "+
+				"ignition file")
+		}
+	} else if file {
+		ignFile, err := os.Open(ign.Content)
+		if err != nil {
+			return "", fmt.Errorf("Error opening supplied Ignition file %s", ign.Content)
+		}
+		defer ignFile.Close()
+		_, err = io.Copy(tempFile, ignFile)
+		if err != nil {
+			return "", fmt.Errorf("Error copying supplied Igition file to temporary file: %s", ign.Content)
+		}
+	}
+	return tempFile.Name(), nil
+}
+
+// Creates a new defIgnition object from provided id
+func newIgnitionDefFromRemoteVol(virConn *libvirt.VirConnection, id string) (defIgnition, error) {
+	ign := defIgnition{}
+
+	key, err := getIgnitionVolumeKeyFromTerraformID(id)
+	if err != nil {
+		return ign, err
+	}
+
+	volume, err := virConn.LookupStorageVolByKey(key)
+	if err != nil {
+		return ign, fmt.Errorf("Can't retrieve volume %s", key)
+	}
+	defer volume.Free()
+
+	ign.Name, err = volume.GetName()
+	if err != nil {
+		return ign, fmt.Errorf("Error retrieving volume name: %s", err)
+	}
+
+	volPool, err := volume.LookupPoolByVolume()
+	if err != nil {
+		return ign, fmt.Errorf("Error retrieving pool for volume: %s", err)
+	}
+	defer volPool.Free()
+
+	ign.PoolName, err = volPool.GetName()
+	if err != nil {
+		return ign, fmt.Errorf("Error retrieving pool name: %s", err)
+	}
+
+
+	return ign, nil
+}
+