Express the highstate schedule in minutes instead of hours

salt.schedule.highstate_interval_hours could not express a sub-hour
cadence, so an operator who disables salt.auto_apply had no way back to
the legacy 15-minute highstate. Rename the setting to
highstate_interval_minutes (default 120, behavior unchanged) and enforce
a 15-minute floor in SOC.

Non-manager splay is now a quarter of the interval clamped to [5, 30]
minutes, so a short interval no longer gets jitter larger than itself; at
the 120-minute default it stays 1800s. The so-salt-minion-check restart
threshold keeps its interval-plus-one-hour grace, now in minute math.

salt/common/tools/sbin_jinja/so-salt-minion-check

@@ -25,7 +25,7 @@ LAST_HIGHSTATE_END=$([ -e "/opt/so/log/salt/lasthighstate" ] && date -r /opt/so/
 LAST_HEALTHCHECK_STATE_APPLY=$([ -e "/opt/so/log/salt/state-apply-test" ] && date -r /opt/so/log/salt/state-apply-test +%s || echo 0)
 # SETTING THRESHOLD TO ANYTHING UNDER 600 seconds may cause a lot of salt-minion restarts since the job to touch the file occurs every 5-8 minutes by default
 # THRESHOLD is derived from the salt schedule highstate interval + 1 hour, so the minion-check grace period tracks the schedule automatically.
-THRESHOLD=$(( ({{ SCHEDULEMERGED.highstate_interval_hours }} + 1) * 3600 )) #within how many seconds the file /opt/so/log/salt/state-apply-test must have been touched/modified before the salt minion is restarted
+THRESHOLD=$(( ({{ SCHEDULEMERGED.highstate_interval_minutes }} + 60) * 60 )) #within how many seconds the file /opt/so/log/salt/state-apply-test must have been touched/modified before the salt minion is restarted
 THRESHOLD_DATE=$((LAST_HEALTHCHECK_STATE_APPLY+THRESHOLD))
 
 logCmd() {

salt/salt/defaults.yaml

@@ -6,4 +6,4 @@ salt:
     batch: '25%'
     batch_wait: 15
   schedule:
-    highstate_interval_hours: 2
+    highstate_interval_minutes: 120

salt/salt/highstate_schedule.sls

@@ -1,11 +1,15 @@
 {% from 'vars/globals.map.jinja' import GLOBALS %}
 {% from 'salt/schedule.map.jinja' import SCHEDULEMERGED %}
 
+{# splay a quarter of the interval, clamped to [5 min, 30 min], so short intervals
+   don't get jitter larger than the interval itself #}
+{% set SPLAY = [[(SCHEDULEMERGED.highstate_interval_minutes * 60 // 4) | int, 300] | max, 1800] | min %}
+
 highstate_schedule:
   schedule.present:
     - function: state.highstate
-    - hours: {{ SCHEDULEMERGED.highstate_interval_hours }}
+    - minutes: {{ SCHEDULEMERGED.highstate_interval_minutes }}
     - maxrunning: 1
 {% if not GLOBALS.is_manager %}
-    - splay: 1800
+    - splay: {{ SPLAY }}
 {% endif %}

salt/salt/soc_salt.yaml

@@ -31,9 +31,11 @@ salt:
       global: True
       advanced: True
   schedule:
-    highstate_interval_hours:
-      description: How often every minion in the grid runs a scheduled state.highstate, in hours. Lower values keep minions closer in sync at the cost of more load; higher values reduce load but increase worst-case latency for non-pushed changes. The salt-minion health check restarts a minion if its last highstate is older than this value plus one hour.
+    highstate_interval_minutes:
+      description: How often every minion in the grid runs a scheduled state.highstate, in minutes. Minimum 15 minutes. Lower values keep minions closer in sync at the cost of more load; higher values reduce load but increase worst-case latency for non-pushed changes. If Auto Apply is disabled, set this to the 15-minute minimum so changes are still picked up promptly. The salt-minion health check restarts a minion if its last state apply is older than this value plus one hour.
       forcedType: int
       helpLink: push
       global: True
       advanced: True
+      regex: '^(1[5-9]|[2-9][0-9]|[1-9][0-9]{2,4})$'
+      regexFailureMessage: The value must be an integer of at least 15 minutes (maximum 99999).