add metadata info

Signed-off-by: GnomeZworc <nicolas.boufidjeline@g3e.fr>

agent/Home.md

@@ -31,3 +31,4 @@ Tout cela serait lancer depuis une api:
 - [Les vms](./agent/instance/Home.md)
 - [Serveur http](./agent/http/Home.md)
 - [Persistance](./agent/persistance/Home.md)
+- [Metadata](./agent/metadata/Home.md)

agent/metadata/Home.md

@@ -0,0 +1,120 @@
+# Metadata server
+
+```go
+package metadata
+
+import (
+	"fmt"
+	"net"
+	"net/http"
+	"strings"
+	"sync"
+)
+
+type Metadata struct {
+	Name    string
+	SSHKeys []string
+}
+
+type Server struct {
+	metadata Metadata
+	listener net.Listener
+	server   *http.Server
+	mu       sync.Mutex
+	port     int
+}
+
+func New(metadata Metadata, port int) *Server {
+	return &Server{
+		metadata: metadata,
+		port:     port,
+	}
+}
+
+func (s *Server) Start() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	addr := fmt.Sprintf("127.0.0.1:%d", s.port)
+	ln, err := net.Listen("tcp", addr)
+	if err != nil {
+		return err
+	}
+	s.listener = ln
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("/meta-data", s.handleMetaData)
+	mux.HandleFunc("/user-data", s.handleUserData)
+
+	s.server = &http.Server{
+		Handler: mux,
+	}
+	go s.server.Serve(ln)
+
+	return nil
+}
+
+func (s *Server) Stop() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if s.server != nil {
+		return s.server.Close()
+	}
+	return nil
+}
+
+func (s *Server) handleMetaData(w http.ResponseWriter, r *http.Request) {
+	fmt.Fprintf(w, "instance-id: %s\n", s.metadata.Name)
+	fmt.Fprintf(w, "local-hostname: %s\n", s.metadata.Name)
+}
+
+func (s *Server) handleUserData(w http.ResponseWriter, r *http.Request) {
+	keys := strings.Join(s.metadata.SSHKeys, "\n  - ")
+	userData := fmt.Sprintf(`#cloud-config
+ssh_authorized_keys:
+  - %s
+`, keys)
+	fmt.Fprint(w, userData)
+}
+```
+
+```go
+type VM struct {
+	Name       string
+	SSHKeys    []string
+	MetaServer *metadata.Server
+	MetaPort   int
+	// ... autres champs comme PID, TAP name, etc.
+}
+
+func StartVM(vm *VM) error {
+	meta := metadata.Metadata{
+		Name:    vm.Name,
+		SSHKeys: vm.SSHKeys,
+	}
+	metaSrv := metadata.New(meta, vm.MetaPort)
+	err := metaSrv.Start()
+	if err != nil {
+		return fmt.Errorf("metadata start failed: %w", err)
+	}
+	vm.MetaServer = metaSrv
+
+	// suite du démarrage de la VM : QEMU, netns, redirection iptables...
+
+	return nil
+}
+
+
+func StopVM(vm *VM) error {
+	// arrêter QEMU, nettoyer TAP, etc...
+
+	if vm.MetaServer != nil {
+		err := vm.MetaServer.Stop()
+		if err != nil {
+			fmt.Printf("Erreur arrêt metadata VM %s: %v\n", vm.Name, err)
+		}
+	}
+	return nil
+}
+```