add support for extending default filter/warn/crit

Changes

@@ -3,6 +3,7 @@ This file documents the revision history for the SNClient+ agent.
 next:
          - update node exporter to 1.8.0
          - add native aarch64 (arm64) packages for windows
+         - add support for extending default filter/warn/crit
          - fix missing scripts in inventory
 
 0.23     Mon Apr 15 17:29:53 CEST 2024

docs/checks/arguments/_index.md

@@ -5,10 +5,13 @@ title: Common Check Arguments
 | Option                          | Description |
 | ------------------------------- | ----------- |
 | [filter](#filter)               | Filter for which items to check |
+| [filter+](#filter-1)            | Same as filter but extend default filter instead of overwriting it. |
 | [warning](#warning)             | Threshold when to generate a warning state |
 | [warn](#warning)                | Short alias for warning |
+| [warning+](#warning-1)          | Same as warning but extend default warning instead of overwriting it |
 | [critical](#critical)           | Threshold when to generate a critical state |
 | [crit](#critical)               | Short alias for critical |
+| [critical+](#critical-1)        | Same as critical but extend default critical instead of overwriting it |
 | [ok](#ok)                       | Threshold when to generate an ok state |
 | [top-syntax](#top-syntax)       | Top level syntax. |
 | [ok-syntax](#ok-syntax)         | Syntax used for ok states. |
@@ -29,6 +32,14 @@ ex.:
 
 Filter are explained in detail here: [check filter](../filter/)
 
+### Filter+
+
+Extend default filter.
+
+ex.:
+
+    'filter+=service = snclient'
+
 ### Warning
 
 Filter which sets a threshold when to generate a warning state. If any wanted item
@@ -41,6 +52,14 @@ ex.:
 
     'warn=load > 90%'
 
+### Warning+
+
+Extend default warning threshold.
+
+ex.:
+
+    'warn+=load > 90%'
+
 ### Critical
 
 Filter which sets a threshold when to generate a critical state. If any wanted item
@@ -53,6 +72,14 @@ ex.:
 
     'crit=load > 98%'
 
+### Critical+
+
+Extend default critical threshold.
+
+ex.:
+
+    'crit+=load > 90%'
+
 ### Ok
 
 Filter which sets a threshold when to generate an ok state. If any wanted item

docs/checks/filter/_index.md

@@ -2,19 +2,40 @@
 title: Filter
 ---
 
-Filter can be uses to select specific objects from a result list. They are also used
-in warning, critical or ok thresholds.
+Filter can be uses to select specific objects from a result list. So if a filter
+is specified, only those elements matching the filter will be considered when
+building the final result.
+
+The same syntax is used for warning/critical/ok thresholds, except when used
+as threshold, the corresponding status will be set.
 
 ## Syntax
 
 All filter follow the syntax `<attribute> <operator> <value>`. For a list and explanation
 of allowed operators see [the operator list](#operator).
 
-The list of possible attributes is documented along with the [check plugins](../plugins).
+The list of possible attributes is documented along with each [check plugin](../plugins).
 
 ex.:
 
-    status = 'started'
+    filter="status = 'started'"
+
+## Default Filter
+
+Some checks do have default filter, which will be used if no filter is supplied
+as check argument.
+
+Default filter are documented along with each [check plugins](../plugins).
+
+The default filter can be unset by using a `none` filter, ex.:
+
+    filter="none"
+
+Default filter will be overwritten if a new filter is set.
+
+Existing default filter can be extended by using a `filter+="..."` syntax, ex.:
+
+    filter+="status = 'started'"
 
 ## Logical Operator
 
@@ -27,7 +48,7 @@ To combine multiple filter you can use logical operator and brackets.
 
 ex.:
 
-    (status = 'started' or status = 'pending') and usage > 5%
+    filter="(status = 'started' or status = 'pending') and usage > 5%"
 
 ## Operator