ssh: load more host key formats than rsa

ssh.go

@@ -23,18 +23,28 @@ func startSSH(cfg *config.Config) {
 		PublicKeyCallback: sshCheckPubkey,
 	}
 
-	pkBytes, err := os.ReadFile("/id_rsa") // TODO configurable
-	if err != nil {
-		fatalf("ssh: failed to load private key: %v", err)
+	hostKeyLoaded := false
+
+	for _, format := range []string{"rsa", "dsa", "ecdsa", "ed25519"} {
+		pkBytes, err := os.ReadFile("/id_" + format)
+		if err != nil {
+			log.Printf("ssh : failed to load %s host key: %v", format, err)
+			continue
+		}
+
+		pk, err := ssh.ParsePrivateKey(pkBytes)
+		if err != nil {
+			log.Printf("ssh: failed to parse %s host key: %v", format, err)
+			continue
+		}
+
+		sshConfig.AddHostKey(pk)
 	}
 
-	pk, err := ssh.ParsePrivateKey(pkBytes)
-	if err != nil {
-		fatalf("ssh: failed to parse private key: %v", err)
+	if !hostKeyLoaded {
+		fatalf("ssh: failed to load any host key")
 	}
 
-	sshConfig.AddHostKey(pk)
-
 	sshBind := ":22" // TODO configurable
 	listener, err := net.Listen("tcp", sshBind)
 	if err != nil {