per-client threshold config

docs/THRESHOLD_ALERTING.md

@@ -56,6 +56,7 @@ thresholds:
       critical: 90.0
       operator: ">"
       hysteresis: 0.1
+      display: "display format"
       enabled: true
 ```
 
@@ -82,6 +83,8 @@ Note: At least one of `warning` or `critical` must be specified.
   - Range: 0.0 to 1.0
   - Prevents rapid state transitions when value hovers near threshold
 
+- **display**: f-string to hold the display format for alert messages
+  - defaults to "(threshold: {op_symbol} {threshold_value})"
 - **enabled**: Whether this threshold is active (default: `true`)
 
 ### Comparison Operators
@@ -740,3 +743,217 @@ Planned features:
 - [Message Journal Documentation](MESSAGE_JOURNAL.md)
 - Configuration examples: `hbd/config_thresholds_example.yaml`
 - Test suite: `test_threshold.py`
+
+## Multi-Threshold Configuration
+
+**New in version 2.0**: Support for multiple named threshold configurations with per-host mapping.
+
+### Overview
+
+The multi-threshold feature allows you to:
+- Define multiple sets of threshold configurations
+- Map different hosts to different threshold sets
+- Use different sensitivity levels for different environments
+- Maintain a default configuration for unmapped hosts
+
+### Configuration Structure
+
+```yaml
+# Optional: Set the default configuration name (defaults to "default")
+default_threshold_config: "default"
+
+# Define multiple named threshold configurations
+threshold_configs:
+  # Configuration name 1
+  default:
+    thresholds:
+      # Standard threshold definitions
+      cpu_monitor:
+        cpu_percent:
+          warning: 80.0
+          critical: 90.0
+  
+  # Configuration name 2
+  high_sensitivity:
+    thresholds:
+      cpu_monitor:
+        cpu_percent:
+          warning: 60.0
+          critical: 75.0
+  
+  # Configuration name 3
+  low_sensitivity:
+    thresholds:
+      cpu_monitor:
+        cpu_percent:
+          warning: 90.0
+          critical: 95.0
+
+# Map specific hosts to specific configurations
+host_threshold_mapping:
+  prod-web-01: high_sensitivity
+  prod-web-02: high_sensitivity
+  dev-server-01: low_sensitivity
+  # Unmapped hosts use default_threshold_config
+```
+
+### Use Cases
+
+#### 1. Environment-Based Thresholds
+
+Different thresholds for production vs. development:
+
+```yaml
+threshold_configs:
+  production:
+    thresholds:
+      cpu_monitor:
+        cpu_percent:
+          warning: 70.0   # Alert earlier in production
+          critical: 85.0
+  
+  development:
+    thresholds:
+      cpu_monitor:
+        cpu_percent:
+          warning: 90.0   # More relaxed for dev
+          critical: 98.0
+
+host_threshold_mapping:
+  prod-web-01: production
+  prod-web-02: production
+  dev-web-01: development
+  dev-web-02: development
+```
+
+#### 2. Server Role-Based Thresholds
+
+Different thresholds based on server function:
+
+```yaml
+threshold_configs:
+  webserver:
+    thresholds:
+      cpu_monitor:
+        cpu_percent:
+          warning: 80.0
+          critical: 90.0
+  
+  database:
+    thresholds:
+      cpu_monitor:
+        cpu_percent:
+          warning: 70.0
+          critical: 85.0
+      memory_monitor:
+        percent:
+          warning: 90.0   # Databases can use high memory
+          critical: 97.0
+      disk_monitor:
+        partitions:
+          /var/lib/mysql:
+            percent:
+              warning: 75.0
+              critical: 85.0
+  
+  cache:
+    thresholds:
+      memory_monitor:
+        percent:
+          warning: 95.0   # Redis/Memcached can use very high memory
+          critical: 99.0
+
+host_threshold_mapping:
+  web-01: webserver
+  web-02: webserver
+  db-01: database
+  db-02: database
+  redis-01: cache
+  memcached-01: cache
+```
+
+#### 3. Sensitivity Levels
+
+Different sensitivity for critical vs. non-critical systems:
+
+```yaml
+threshold_configs:
+  critical:
+    thresholds:
+      disk_monitor:
+        partitions:
+          /:
+            percent:
+              warning: 70.0    # Very sensitive
+              critical: 80.0
+              hysteresis: 0.15
+  
+  standard:
+    thresholds:
+      disk_monitor:
+        partitions:
+          /:
+            percent:
+              warning: 85.0
+              critical: 95.0
+              hysteresis: 0.1
+  
+  relaxed:
+    thresholds:
+      disk_monitor:
+        partitions:
+          /:
+            percent:
+              warning: 90.0
+              critical: 98.0
+              hysteresis: 0.05
+
+host_threshold_mapping:
+  payment-gateway: critical
+  auth-server: critical
+  web-01: standard
+  web-02: standard
+  test-server: relaxed
+```
+
+### 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-specific mapping**: If host is in `host_threshold_mapping`, use that config
+2. **Default config**: Use `default_threshold_config` 
+3. **First alphabetically**: If default not found, use first config alphabetically
+4. **Legacy fallback**: If `threshold_configs` not present, use `thresholds`
+
+### Example: Complete Multi-Threshold Setup
+
+See `hbd/config_multi_threshold_example.yaml` for a complete example with:
+- 4 named configurations (default, high_sensitivity, low_sensitivity, database)
+- Host-to-config mappings for production, development, and test systems
+- Specialized database server thresholds
+- Custom display messages with plugin data
+