From 4ecf05bf82a6ee78641398a36451f0fee2e6b626 Mon Sep 17 00:00:00 2001
From: Matthew Stobbs <matthew@stobbs.ca>
Date: Sun, 10 Mar 2024 20:32:11 -0600
Subject: [PATCH] Adding basic wrappers

- Wrapper for Host connection called Host
  - Allows for easier usage of the API
- Wrapper for Domains called GuestVM, which pulls VM information and allows
  other functionality in a better way
---
 README.md  | 18 ++++++++++++++
 domains.go | 53 +++++++++++++++++++++++++++++++++++++++++
 host.go    | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 main.go    | 16 ++++++-------
 4 files changed, 147 insertions(+), 9 deletions(-)
 create mode 100644 domains.go
 create mode 100644 host.go

diff --git a/README.md b/README.md
index d437d29..768167e 100644
--- a/README.md
+++ b/README.md
@@ -54,3 +54,21 @@ Overall goals:
     - Connection management (to other libvirt hosts)
 - Create a simple WebUI with HTMX to monitor that stuff
 - Add the ability to manage that stuff once we can monitor it, through the WebUI.
+
+## Special XMLNS definitions
+
+### Domain
+
+- `xmlns:clustvirt="https://git.staur.ca/stobbsm/clustvirt"`
+
+```xml
+<metadata>
+    <clustvirt:data xmlns:clustvirt="https://git.staur.ca/stobbsm/clustvirt/">
+        <clustvirt:created>true</clustvirt:created>
+        <clustvirt:managed>true</clustvirt:managed>
+        <clustvirt:currentHost>host01</clustvirt:currentHost>
+        <clustvirt:origHost>host02</clustvirt:origHost>
+        <clustvirt:baseGuest>rocky-9-base</clustvirt:baseGuest>
+    </clustvirt:data>
+</metadata>
+```
diff --git a/domains.go b/domains.go
new file mode 100644
index 0000000..d6d8671
--- /dev/null
+++ b/domains.go
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"libvirt.org/go/libvirt"
+)
+// GuestVM holds a handle is used to communicate to Domains
+type GuestVM struct {
+	Name      string
+	ID        uint
+	BackupXML string
+
+	close    chan struct{}
+	closeErr chan error
+	dom      *libvirt.Domain
+}
+
+// GetGuest loads guest information by name and returns it
+func GetGuest(name string, conn *libvirt.Connect) (*GuestVM, error) {
+	g := &GuestVM{
+		Name: name,
+		close:    make(chan struct{}),
+		closeErr: make(chan error),
+	}
+
+	var err error
+
+	if g.dom, err = conn.LookupDomainByName(name); err != nil {
+		return nil, err
+	}
+	if g.ID, err = g.dom.GetID(); err != nil {
+		return nil, err
+	}
+	if g.BackupXML, err = g.dom.BackupGetXMLDesc(0); err != nil {
+		return nil, err
+	}
+
+	go func() {
+		defer close(g.closeErr)
+		<-g.close
+		g.closeErr <- g.dom.Free()
+	}()
+
+	return g, nil
+}
+
+// Close closes an open connection
+func (g *GuestVM) Close() error {
+	close(g.close)
+	return <-g.closeErr
+}
diff --git a/host.go b/host.go
new file mode 100644
index 0000000..03b21e5
--- /dev/null
+++ b/host.go
@@ -0,0 +1,69 @@
+package main
+
+import (
+	"fmt"
+
+	"libvirt.org/go/libvirt"
+)
+
+// Host holds information and acts as a connection handle for a Host
+// If a connection is closed prematurely, will re-open the connection and
+// try the attempted method again
+type Host struct {
+	HostName string
+
+	conn     *libvirt.Connect
+	close    chan struct{}
+	closeErr chan error
+}
+
+// ConnectHost creates a host connection wrapper that can be used regularly
+func ConnectHost(host string) (*Host, error) {
+	h := &Host{
+		HostName: host,
+	}
+
+	if err := h.connect(); err != nil {
+		return nil, err
+	}
+
+	h.close = make(chan struct{})
+	h.closeErr = make(chan error)
+
+	go func() {
+		defer close(h.closeErr)
+		<-h.close
+		_, err := h.conn.Close()
+		h.closeErr <- err
+	}()
+	return h, nil
+}
+
+// connect creates a host connection
+func (h *Host) connect() error {
+	var err error
+	h.conn, err = libvirt.NewConnect(
+		fmt.Sprintf("qemu+ssh://%s/system", h.HostName),
+	)
+	return err
+}
+
+// GetGuestByName returns a GuestVM instance that exists on the given host
+func (h *Host) GetGuestByName(name string) (*GuestVM, error) {
+	if g, err := GetGuest(name, h.conn); err == nil {
+		return g, nil
+	} else {
+		lverr, ok := err.(libvirt.Error)
+		if ok && lverr.Code == libvirt.ERR_INVALID_CONN {
+			// try again after creating a new connection
+			return GetGuest(name, h.conn)
+		}
+		return nil, err
+	}
+}
+
+// Close triggers closing the host connection
+func (h *Host) Close() error {
+	close(h.close)
+	return <-h.closeErr
+}
diff --git a/main.go b/main.go
index 634696b..8f7de0f 100644
--- a/main.go
+++ b/main.go
@@ -2,23 +2,21 @@ package main
 
 import (
 	"log"
-
-	"libvirt.org/go/libvirt"
 )
 
 func main() {
 	log.Println("Starting clustvirt, the libvirt cluster manager")
 
 	// Try connecting to libvirt
-	conn, err := libvirt.NewConnect("qemu+ssh://earth.staur.ca/system")
+	doms, err := GetDomsInCluster("earth.staur.ca", "mars.staur.ca", "venus.staur.ca")
 	if err != nil {
 		log.Fatal(err)
 	}
-	defer conn.Close()
-
-	doms, err := conn.ListAllDomains(libvirt.CONNECT_LIST_DOMAINS_ACTIVE | libvirt.CONNECT_LIST_DOMAINS_INACTIVE)
-	if err != nil {
-		log.Fatal(err)
+	log.Printf("Domains in cluster: %d", len(doms))
+	// Example of xmlns uri found in libvirt xml definition:
+	// xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0"
+	for _, d := range doms {
+		log.Println(d.GetMetadata(0, "", 0))
+		d.Free()
 	}
-	log.Printf("Domains on earth: %d", len(doms))
 }