confd: new NTP setting stratum-weight

This patch adds support for chronyd's stratumpweight both in the NTP
client (ietf-system) and client+server (ietf-ntp) should fix the flaky
NTP stratum test.

Also, make sure to *not* 'rm -rf /etc/chrony/conf.d/*' in system.c to
prevent clobbering settings potentially made in ntp.c

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/confd/src/ntp.c

@@ -18,7 +18,7 @@ static int change(sr_session_ctx_t *session, struct lyd_node *config, struct lyd
 		  sr_event_t event, struct confd *confd)
 {
 	struct lyd_node *ntp, *entry, *makestep, *refclock;
-	const char *port;
+	const char *port, *sw;
 	FILE *fp;
 
 	if (diff && !lydx_get_xpathf(diff, XPATH_NTP_))
@@ -68,6 +68,11 @@ static int change(sr_session_ctx_t *session, struct lyd_node *config, struct lyd
 	fprintf(fp, "# Generated by confd\n");
 	fprintf(fp, "# This file configures chronyd as an NTP server\n\n");
 
+	/* Global NTP source selection options */
+	sw = lydx_get_cattr(ntp, "stratum-weight");
+	if (sw)
+		fprintf(fp, "stratumweight %s\n\n", sw);
+
 	/* Port configuration (optional) */
 	port = lydx_get_cattr(ntp, "port");
 	if (port) {

src/confd/src/system.c

@@ -25,6 +25,7 @@
 #define XPATH_BASE_        "/ietf-system:system"
 #define XPATH_AUTH_        XPATH_BASE_"/authentication"
 #define XPATH_NTP_         XPATH_BASE_"/ntp"
+#define NTP_CLIENT_CONF    "/etc/chrony/conf.d/ntp-client.conf"
 #define XPATH_DNS_         XPATH_BASE_"/dns-resolver"
 #define XPATH_HOSTNAME_    XPATH_BASE_"/hostname"
 #define XPATH_MOTD_BANNER_ XPATH_BASE_"/infix-system:motd-banner"
@@ -304,7 +305,8 @@ static int change_ntp_client(sr_session_ctx_t *session, struct lyd_node *config,
 
 	case SR_EV_DONE:
 		if (!srx_enabled(session, XPATH_NTP_"/enabled")) {
-			systemf("rm -rf /etc/chrony/conf.d/* /etc/chrony/sources.d/*");
+			(void)remove(NTP_CLIENT_CONF);
+			systemf("rm -f /etc/chrony/sources.d/*");
 			/* Note: chronyd enable/disable is managed centrally in core.c */
 			systemf("initctl -nbq touch chronyd");
 			return SR_ERR_OK;
@@ -405,6 +407,23 @@ static int change_ntp_client(sr_session_ctx_t *session, struct lyd_node *config,
 	}
 	sr_free_values(val, cnt);
 
+	/* Write global NTP client options (stratumweight, etc.) to conf.d */
+	if (srx_enabled(session, XPATH_NTP_"/enabled")) {
+		char *sw = srx_get_str(session, XPATH_NTP_"/infix-system:stratum-weight");
+		FILE *fp = fopen(NTP_CLIENT_CONF, "w");
+
+		if (fp) {
+			fprintf(fp, "# Generated by confd\n");
+			if (sw)
+				fprintf(fp, "stratumweight %s\n", sw);
+			fclose(fp);
+		} else {
+			ERRNO("Failed creating %s", NTP_CLIENT_CONF);
+		}
+		if (sw)
+			free(sw);
+	}
+
 	if (changes) {
 		if (touch("/run/chrony/.changes"))
 			ERRNO("Failed recording changes to NTP client");

src/confd/yang/confd.inc

@@ -42,7 +42,7 @@ MODULES=(
 	"infix-firewall-services@2025-04-26.yang"
 	"infix-firewall-icmp-types@2025-04-26.yang"
 	"infix-meta@2025-12-10.yang"
-	"infix-system@2025-12-02.yang"
+	"infix-system@2026-03-09.yang"
 	"infix-services@2025-12-10.yang"
 	"ieee802-ethernet-interface@2019-06-21.yang"
 	"infix-ethernet-interface@2024-02-27.yang"
@@ -51,6 +51,6 @@ MODULES=(
 	"ietf-crypto-types -e cleartext-symmetric-keys"
 	"infix-crypto-types@2025-11-09.yang"
 	"ietf-keystore -e symmetric-keys"
-	"infix-ntp@2026-02-08.yang"
+	"infix-ntp@2026-03-09.yang"
 	"infix-keystore@2025-12-17.yang"
 )

src/confd/yang/confd/infix-ntp.yang

@@ -29,6 +29,15 @@ module infix-ntp {
   contact      "kernelkit@googlegroups.com";
   description  "Infix deviations and augments to ietf-ntp.";
 
+  revision 2026-03-09 {
+    description "Add stratumweight to NTP server configuration.
+
+                 Allows tuning the weight of stratum in NTP source selection
+                 relative to measured distance. Setting to 0.0 ensures lower
+                 stratum sources are always preferred regardless of distance.";
+    reference "internal";
+  }
+
   revision 2026-02-08 {
     description
       "Add GPS/GNSS reference clock support.
@@ -56,6 +65,25 @@ module infix-ntp {
    */
 
   augment "/ntp:ntp" {
+    leaf stratum-weight {
+      type decimal64 {
+        fraction-digits 3;
+        range "0.0..max";
+      }
+      default "0.001";
+      units "seconds";
+      description
+        "Weight of stratum in NTP source selection relative to measured distance.
+
+         A one-stratum difference counts as this many seconds of additional
+         distance when comparing candidates.
+
+         The default (0.001 = 1ms) means stratum only wins when distance
+         differences are less than 1ms. Setting it to 0.0 ensures that a
+         lower-stratum source is always preferred over a higher-stratum source,
+         regardless of their measured distances.";
+    }
+
     container makestep {
       presence "Enable clock stepping for large offsets";
       description

src/confd/yang/confd/infix-system.yang

@@ -28,6 +28,15 @@ module infix-system {
   contact      "kernelkit@googlegroups.com";
   description  "Infix augments and deviations to ietf-system.";
 
+  revision 2026-03-09 {
+    description "Add stratumweight to NTP client configuration.
+
+                 Allows tuning the weight of stratum in NTP source selection
+                 relative to measured distance. Setting to 0.0 ensures lower
+                 stratum sources are always preferred regardless of distance.";
+    reference "internal";
+  }
+
   revision 2025-12-02 {
     description "Extend services with runtime statistics:
                    - Add statistics container with memory-usage, uptime, restart-count";
@@ -307,6 +316,27 @@ module infix-system {
     }
   }
 
+  augment "/sys:system/sys:ntp" {
+    leaf stratum-weight {
+      type decimal64 {
+        fraction-digits 3;
+        range "0.0..max";
+      }
+      default "0.001";
+      units "seconds";
+      description
+        "Weight of stratum in NTP source selection relative to measured distance.
+
+         A one-stratum difference counts as this many seconds of additional
+         distance when comparing candidates.
+
+         The default (0.001 = 1ms) means stratum only wins when distance
+         differences are less than 1ms. Setting it to 0.0 ensures that a
+         lower-stratum source is always preferred over a higher-stratum source,
+         regardless of their measured distances.";
+    }
+  }
+
   augment "/sys:system/sys:authentication/sys:user" {
     description "Augment of ietf-system to support setting login shell for users.";
     leaf shell {

test/case/ntp/client_stratum_selection/test.py

@@ -107,6 +107,7 @@ with infamy.Test() as test:
                         "system": {
                             "ntp": {
                                 "enabled": True,
+                                "infix-system:stratum-weight": 0.0,
                                 "server": [{
                                     "name": "srv1",
                                     "udp": {