feat: nagios operator for direct exit-code severity mapping

Add ComparisonOperator.NAGIOS ("nagios") that maps Nagios exit codes
directly to alert levels (0=OK 1=WARNING 2=CRITICAL 3=UNKNOWN) without
requiring numeric warning/critical thresholds. Hysteresis is bypassed for
discrete codes. Display template defaults to "{check_name}: {output}".
_format_display() handles None threshold_value gracefully.

Add nagios_runner.status_code as a built-in default threshold config so
nagios checks alert out of the box.

Also: fix alerts.html scrolling (override html,body), make hostname a link
to /plugins#<hostname>, remove overall_status/overall_status_code/plugin_count
from nagios_runner and hbc_mini, replace with computed worst-status in
plugins.html via nagiosWorstStatus() helper.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -296,7 +296,7 @@ Available variables:
 |---|---|
 | `{value}` | Current metric value |
 | `{threshold_value}` | Threshold that was crossed |
-| `{op_symbol}` | Comparison operator (`>`, `<`, `>=`, …) |
+| `{op_symbol}` | Comparison operator (`>`, `<`, `>=`, …); `"nagios"` for the nagios operator |
 | `{check_name}` | Prefix stripped by generic matching (see below) |
 | `{metric_name}` | Full field name within the plugin data |
 | `{output}` | For `nagios_runner` generic matches: the matched check's status text (alias for `{check_name}_output`) |
@@ -316,15 +316,13 @@ nagios_runner.root_status_code               → no match
 nagios_runner.status_code                    → matched ✓
 ```
 
-Configure the generic threshold once:
+Configure the generic threshold once using the `nagios` operator, which maps exit codes directly to alert severity without requiring numeric warning/critical values:
 
 ```yaml
 nagios_runner:
   status_code:
-    warning: 1
+    operator: "nagios"   # 0=OK  1=WARNING  2=CRITICAL  3=UNKNOWN
-    critical: 2
+    display: "{check_name}: {output}"
-    operator: ">="
-    display: "{check_name}: exit {value}"
 ```
 
 The stripped prefix (`check_disk_root` in the example above) is available as `{check_name}` in the display template, so you can identify which check triggered the alert without writing a separate threshold entry per command.

docs/NAGIOS_INTEGRATION.md

@@ -104,11 +104,6 @@ The `nagios_runner` plugin collects:
 - `{name}_{metric}_min` - Minimum value (if present)
 - `{name}_{metric}_max` - Maximum value (if present)
 
-**Overall:**
-- `overall_status` - Worst status from all commands
-- `overall_status_code` - Worst status code
-- `plugin_count` - Number of Nagios plugins executed
-
 ## Configuration Options
 
 ```yaml

docs/THRESHOLD_ALERTING.md

@@ -1110,33 +1110,6 @@ hosts:
   db-02:
     threshold_config: [tight_memory, db_disk]
 ```
-
-### Backward Compatibility
-
-The legacy single threshold configuration is fully supported:
-
-```yaml
-# Old format - still works
-thresholds:
-  cpu_monitor:
-    cpu_percent:
-      warning: 80.0
-      critical: 90.0
-```
-
-This is equivalent to:
-
-```yaml
-# New format
-threshold_configs:
-  default:
-    thresholds:
-      cpu_monitor:
-        cpu_percent:
-          warning: 80.0
-          critical: 90.0
-```
-
 ### Configuration Priority
 
 1. **Host `threshold_config` (list)**: Layer each named config's overrides left-to-right on top of the defaults

hbd/server/config.py

@@ -95,6 +95,12 @@ THRESHOLD_DEFAULTS = {
                 'warning': 200,
                 'critical': 250.0,
                 'count': 3  # Optional: number of consecutive breaches before alerting
+            },
+            'nagios_runner': {
+                'status_code': {
+                    'display': '{check_name} {output}',
+                    'operator': "nagios"
+                }   
             }
         }
     }

hbd/server/templates/alerts.html

@@ -437,7 +437,7 @@
             <div class="alert-main">
               <div class="alert-header">
                 <span class="alert-level ${level}">${alert.level}</span>
-                <a class="alert-hostname" href="/plugins/${alert.hostname}">${alert.hostname}</a>
+                <a class="alert-hostname" href="/plugins#${alert.hostname}">${alert.hostname}</a>
               </div>
               <div class="alert-metric">${alert.metric_path}</div>
               <div class="alert-details">

hbd/server/templates/plugins.html

@@ -499,6 +499,17 @@
         return pluginCache[hostname]?.[pluginName] ?? null;
       }
 
+      // Return worst nagios exit code (0-3) found in a nagios_runner data object.
+      function nagiosWorstStatus(data) {
+        let worst = 0;
+        for (const [k, v] of Object.entries(data || {})) {
+          if (k.endsWith('_status_code') && typeof v === 'number' && v > worst) {
+            worst = v;
+          }
+        }
+        return worst;
+      }
+
       // ── Fetch helpers ───────────────────────────────────────────────────────
 
       async function fetchPlugin(hostname, pluginName) {
@@ -600,13 +611,13 @@
           ? chips.join('')
           : '<span class="glance-loading">—</span>';
 
-        // Nagios badge
+        // Nagios badge — derive worst status from individual check codes
         const nagios = getCache(hostname, 'nagios_runner');
         if (nagosBadge && nagios) {
-          const status = (nagios.data.overall_status || '—').toUpperCase();
+          const worst = nagiosWorstStatus(nagios.data);
-          const cls = status === 'OK' ? 'ok'
+          const names = {0:'OK', 1:'WARNING', 2:'CRITICAL', 3:'UNKNOWN'};
-            : status === 'WARNING' ? 'warning'
+          const status = names[worst] || '—';
-            : status === 'CRITICAL' ? 'critical' : '';
+          const cls = worst === 0 ? 'ok' : worst === 1 ? 'warning' : worst >= 2 ? 'critical' : '';
           nagosBadge.className = `nagios-badge ${cls}`;
           nagosBadge.textContent = status;
         }
@@ -715,9 +726,10 @@
             break;
           }
           case 'nagios_runner': {
-            const status = (d.overall_status || '?').toUpperCase();
+            const worst = nagiosWorstStatus(d);
-            const count = d.plugin_count;
+            const names = {0:'OK', 1:'WARNING', 2:'CRITICAL', 3:'UNKNOWN'};
-            text = status + (count != null ? ` — ${count} checks` : '');
+            const codes = Object.keys(d).filter(k => k.endsWith('_status_code'));
+            text = (names[worst] || '?') + (codes.length ? ` — ${codes.length} checks` : '');
             break;
           }
           case 'filesystem_info': {

hbd/server/threshold.py

@@ -30,12 +30,13 @@ class AlertLevel(Enum):
 
 class ComparisonOperator(Enum):
     """Supported comparison operators for threshold checks."""
-    GT = ">"      # Greater than
+    GT = ">"        # Greater than
-    GTE = ">="    # Greater than or equal
+    GTE = ">="      # Greater than or equal
-    LT = "<"      # Less than
+    LT = "<"        # Less than
-    LTE = "<="    # Less than or equal
+    LTE = "<="      # Less than or equal
-    EQ = "=="     # Equal to
+    EQ = "=="       # Equal to
-    NEQ = "!="    # Not equal to
+    NEQ = "!="      # Not equal to
+    NAGIOS = "nagios"  # Nagios exit-code semantics: 0=OK 1=WARNING 2=CRITICAL 3=UNKNOWN
 
 
 class AlertState:
@@ -229,33 +230,43 @@ class ThresholdConfig:
     def evaluate(self, value: float) -> AlertLevel:
         """
         Evaluate a value against this threshold.
-        
+
         Args:
             value: Metric value to check
-            
+
         Returns:
             AlertLevel indicating the severity
         """
         if not self.enabled:
             return AlertLevel.OK
-        
+
+        # Nagios exit-code semantics: value IS the severity
+        if self.operator == ComparisonOperator.NAGIOS:
+            try:
+                code = int(value)
+            except (TypeError, ValueError):
+                return AlertLevel.UNKNOWN
+            return {0: AlertLevel.OK, 1: AlertLevel.WARNING, 2: AlertLevel.CRITICAL}.get(
+                code, AlertLevel.UNKNOWN
+            )
+
         try:
             # Convert value to float for comparison
             value = float(value)
         except (TypeError, ValueError):
             logger.warning("Cannot convert value %s to float for %s", value, self.metric_path)
             return AlertLevel.UNKNOWN
-        
+
         # Check critical threshold first
         if self.critical is not None:
             if self._compare(value, self.critical):
                 return AlertLevel.CRITICAL
-        
+
         # Then check warning threshold
         if self.warning is not None:
             if self._compare(value, self.warning):
                 return AlertLevel.WARNING
-        
+
         return AlertLevel.OK
     
     def evaluate_with_hysteresis(
@@ -274,7 +285,11 @@ class ThresholdConfig:
             New alert level considering hysteresis
         """
         new_level = self.evaluate(value)
-        
+
+        # Nagios exit codes are discrete integers — hysteresis doesn't apply
+        if self.operator == ComparisonOperator.NAGIOS:
+            return new_level
+
         # If no hysteresis, return new level
         if self.hysteresis == 0.0:
             return new_level
@@ -557,11 +572,14 @@ class ThresholdChecker:
             warning = threshold_config.get("warning")
             critical = threshold_config.get("critical")
             operator = threshold_config.get("operator", ">")
-            display = threshold_config.get("display", "(threshold: {op_symbol} {threshold_value})")
+            # Nagios operator maps exit codes directly; no numeric thresholds needed
-            hysteresis = threshold_config.get("hysteresis", 0.02)  # 2% default
+            is_nagios_op = (operator == "nagios")
+            default_display = "{check_name}: {output}" if is_nagios_op else "(threshold: {op_symbol} {threshold_value})"
+            display = threshold_config.get("display", default_display)
+            hysteresis = threshold_config.get("hysteresis", 0.0 if is_nagios_op else 0.02)
             enabled = threshold_config.get("enabled", True)
-            
+
-            if warning is None and critical is None:
+            if warning is None and critical is None and not is_nagios_op:
                 logger.warning("No thresholds defined for %s, skipping", metric_path)
                 continue
             
@@ -1016,48 +1034,12 @@ class ThresholdChecker:
         import math
         display_value = "overdue" if isinstance(value, float) and math.isinf(value) else value
 
-        # Format message
+        # Format message — for the nagios operator there is no numeric threshold_value;
-        if new_level == AlertLevel.OK:
+        # render the display template whenever one is available.
-            lvl = "RECOVER"
+        has_display = threshold_value is not None or threshold.operator == ComparisonOperator.NAGIOS
-            message = f"{metric_path} = {display_value} ({old_level.name} -> OK)"
-        elif new_level == AlertLevel.WARNING:
-            lvl = "WARNING"
-            if threshold_value is not None:
-                threshold_info = self._format_display(
-                    threshold.display,
-                    value=display_value,
-                    threshold_value=threshold_value,
-                    op_symbol=op_symbol,
-                    plugin_data=plugin_data,
-                    check_name=check_name,
-                    metric_name=metric_name,
-                )
-                message = f"{metric_path} = {display_value} {threshold_info}"
-            else:
-                message = f"{metric_path} = {display_value}"
-        elif new_level == AlertLevel.CRITICAL:
-            lvl = "CRITICAL"
-            if threshold_value is not None:
-                threshold_info = self._format_display(
-                    threshold.display,
-                    value=display_value,
-                    threshold_value=threshold_value,
-                    op_symbol=op_symbol,
-                    plugin_data=plugin_data,
-                    check_name=check_name,
-                    metric_name=metric_name,
-                )
-                message = f"{metric_path} = {display_value} {threshold_info}"
-            else:
-                message = f"{metric_path} = {display_value}"
-        else:
-            lvl = "UNKNOWN"
-            message = f"{metric_path} = {display_value}"
 
-        # Return the formatted threshold info for storing in AlertState
+        def _fmt():
-        formatted_threshold_msg = None
+            return self._format_display(
-        if threshold_value is not None and new_level != AlertLevel.OK:
-            formatted_threshold_msg = self._format_display(
                 threshold.display,
                 value=display_value,
                 threshold_value=threshold_value,
@@ -1067,6 +1049,31 @@ class ThresholdChecker:
                 metric_name=metric_name,
             )
 
+        if new_level == AlertLevel.OK:
+            lvl = "RECOVER"
+            message = f"{metric_path} = {display_value} ({old_level.name} -> OK)"
+        elif new_level == AlertLevel.WARNING:
+            lvl = "WARNING"
+            if has_display:
+                message = f"{metric_path} = {display_value} {_fmt()}"
+            else:
+                message = f"{metric_path} = {display_value}"
+        elif new_level == AlertLevel.CRITICAL:
+            lvl = "CRITICAL"
+            if has_display:
+                message = f"{metric_path} = {display_value} {_fmt()}"
+            else:
+                message = f"{metric_path} = {display_value}"
+        else:
+            lvl = "UNKNOWN"
+            if has_display:
+                message = f"{metric_path} = {display_value} {_fmt()}"
+            else:
+                message = f"{metric_path} = {display_value}"
+
+        # Formatted threshold info stored on AlertState for the UI
+        formatted_threshold_msg = _fmt() if has_display and new_level != AlertLevel.OK else None
+
         return lvl, message, formatted_threshold_msg
     
     def _send_notification(
@@ -1114,7 +1121,7 @@ class ThresholdChecker:
         self,
         display_format: str,
         value: Any,
-        threshold_value: float,
+        threshold_value: Optional[float],
         op_symbol: str,
         plugin_data: Optional[Dict[str, Any]] = None,
         check_name: Optional[str] = None,
@@ -1139,9 +1146,10 @@ class ThresholdChecker:
         # Build format context with standard variables
         format_context = {
             'value': value,
-            'threshold_value': threshold_value,
             'op_symbol': op_symbol,
         }
+        if threshold_value is not None:
+            format_context['threshold_value'] = threshold_value
 
         # Add generic-match context variables when available
         if check_name is not None:

scripts/hbc_mini.py

@@ -388,7 +388,6 @@ class NagiosRunnerPlugin(MonitorPlugin):
 
     async def _collect_metrics(self) -> Dict[str, Any]:
         results: Dict[str, Any] = {}
-        worst = 0
         for cmd_cfg in self.commands:
             name = cmd_cfg.get("name")
             command = cmd_cfg.get("command")
@@ -399,10 +398,6 @@ class NagiosRunnerPlugin(MonitorPlugin):
             results[f"{name}_status_code"] = rc
             results[f"{name}_output"] = msg
             results.update({f"{name}_{k}": v for k, v in perf.items()})
-            worst = max(worst, rc)
-        results["overall_status"] = _NAGIOS_STATUS.get(worst, "UNKNOWN")
-        results["overall_status_code"] = worst
-        results["plugin_count"] = len(self.commands)
         return results
 
 

test_nagios.py

@@ -68,8 +68,7 @@ async def test_nagios_runner():
     print(f"   ✓ Collected {len(data)} data points")
     
     print(f"\n4. Results:")
-    print(f"   Overall Status: {data.get('overall_status')} (code: {data.get('overall_status_code')})")
+    print(f"   Data points collected: {len(data)}")
-    print(f"   Plugins Executed: {data.get('plugin_count')}")
     
     # Show individual plugin results
     print(f"\n5. Individual Plugin Results:")