fix agent data directory resolution (#991)

beszel/cmd/agent/agent.go

@@ -111,7 +111,7 @@ func main() {
 	serverConfig.Addr = addr
 	serverConfig.Network = agent.GetNetwork(addr)
 
-	agent, err := agent.NewAgent("")
+	agent, err := agent.NewAgent()
 	if err != nil {
 		log.Fatal("Failed to create agent: ", err)
 	}

beszel/internal/agent/agent.go

@@ -40,13 +40,13 @@ type Agent struct {
 
 // NewAgent creates a new agent with the given data directory for persisting data.
 // If the data directory is not set, it will attempt to find the optimal directory.
-func NewAgent(dataDir string) (agent *Agent, err error) {
+func NewAgent(dataDir ...string) (agent *Agent, err error) {
 	agent = &Agent{
 		fsStats: make(map[string]*system.FsStats),
 		cache:   NewSessionCache(69 * time.Second),
 	}
 
-	agent.dataDir, err = getDataDir(dataDir)
+	agent.dataDir, err = getDataDir(dataDir...)
 	if err != nil {
 		slog.Warn("Data directory not found")
 	} else {

supplemental/scripts/install-agent.sh

@@ -453,6 +453,11 @@ set_selinux_context
 # Cleanup
 rm -rf "$TEMP_DIR"
 
+# Make sure /etc/machine-id exists for persistent fingerprint
+if [ ! -f /etc/machine-id ]; then
+  cat /proc/sys/kernel/random/uuid | tr -d '-' > /etc/machine-id
+fi
+
 # Check for NVIDIA GPUs and grant device permissions for systemd service
 detect_nvidia_devices() {
   local devices=""