feat(agent): activation zéro-config – config Headscale envoyée par le serveur

- Agent: URL serveur par défaut, node_id auto-généré, config Headscale vide par défaut
- Serveur: lors de l’activation, renvoie headscaleUrl + headscaleAuthKey
- Agent: sauvegarde la config reçue et démarre Tailscale automatiquement
- docker-compose.yml: passe HEADSCALE_URL et HEADSCALE_AUTH_KEY au service server
- Mise à jour du suivi avec le flow zéro-config

agent/config.go

@@ -1,7 +1,10 @@
 package main
 
 import (
+	"crypto/rand"
+	"encoding/hex"
 	"encoding/json"
+	"fmt"
 	"os"
 	"path/filepath"
 )
@@ -17,17 +20,55 @@ type AgentConfig struct {
 
 const configFileName = "studioE5-config.json"
 
+// defaultServerURL is the production WebSocket endpoint baked into the agent.
+// It can be overridden by the config file for self-hosted or test setups.
+const defaultServerURL = "wss://studioe5.edudeploy.com/api/websocket"
+
+// uniqueNodeID returns a stable-ish unique identifier for this machine.
+// It combines the hostname with a short random suffix so every install is distinct.
+func uniqueNodeID() string {
+	h, err := os.Hostname()
+	if err != nil || h == "" {
+		h = "node"
+	}
+	b := make([]byte, 4)
+	if _, err := rand.Read(b); err == nil {
+		return fmt.Sprintf("%s-%s", h, hex.EncodeToString(b))
+	}
+	return fmt.Sprintf("%s-%d", h, os.Getpid())
+}
+
 // defaultConfig returns sensible defaults for a first run.
+// The user only needs to provide an activation code; Headscale credentials are
+// delivered by the server during activation.
 func defaultConfig(dataDir string) *AgentConfig {
 	return &AgentConfig{
-		Server:           "ws://localhost:3001",
+		Server:           defaultServerURL,
 		HeadscaleURL:     "",
 		HeadscaleAuthKey: "",
-		NodeID:           defaultNodeID(),
+		NodeID:           uniqueNodeID(),
 		DataDir:          dataDir,
 	}
 }
 
+// mergeWithDefaults fills missing fields from disk with sensible defaults.
+func mergeWithDefaults(cfg *AgentConfig, dataDir string) *AgentConfig {
+	defaults := defaultConfig(dataDir)
+	if cfg == nil {
+		return defaults
+	}
+	if cfg.Server == "" {
+		cfg.Server = defaults.Server
+	}
+	if cfg.NodeID == "" {
+		cfg.NodeID = defaults.NodeID
+	}
+	if cfg.DataDir == "" {
+		cfg.DataDir = defaults.DataDir
+	}
+	return cfg
+}
+
 // configPath returns the absolute path to the config file.
 func configPath(dataDir string) string {
 	return filepath.Join(dataDir, configFileName)
@@ -43,11 +84,12 @@ func loadOrCreateConfig(dataDir string) (*AgentConfig, bool, error) {
 		if err != nil {
 			return nil, false, err
 		}
-		var cfg AgentConfig
-		if err := json.Unmarshal(data, &cfg); err != nil {
+		cfg := &AgentConfig{}
+		if err := json.Unmarshal(data, cfg); err != nil {
 			return nil, false, err
 		}
-		return &cfg, false, nil
+		cfg = mergeWithDefaults(cfg, dataDir)
+		return cfg, false, nil
 	}
 
 	cfg := defaultConfig(dataDir)
@@ -60,9 +102,12 @@ func loadOrCreateConfig(dataDir string) (*AgentConfig, bool, error) {
 // saveConfig writes the config file to disk.
 func saveConfig(dataDir string, cfg *AgentConfig) error {
 	cp := configPath(dataDir)
+	if err := os.MkdirAll(dataDir, 0755); err != nil {
+		return err
+	}
 	data, err := json.MarshalIndent(cfg, "", "  ")
 	if err != nil {
 		return err
 	}
-	return os.WriteFile(cp, data, 0644)
+	return os.WriteFile(cp, data, 0600)
 }