add Hostname helper in expr and templating (#2193)

pkg/csplugin/helpers.go

@@ -1,6 +1,7 @@
 package csplugin
 
 import (
+	"os"
 	"text/template"
 
 	"github.com/crowdsecurity/crowdsec/pkg/exprhelpers"
@@ -20,6 +21,7 @@ var helpers = template.FuncMap{
 		return metaValues
 	},
 	"CrowdsecCTI": exprhelpers.CrowdsecCTI,
+	"Hostname":    os.Hostname,
 }
 
 func funcMap() template.FuncMap {

pkg/exprhelpers/expr_lib.go

@@ -398,6 +398,13 @@ var exprFuncs = []exprCustomFunc{
 			new(func(string) string),
 		},
 	},
+	{
+		name:     "Hostname",
+		function: Hostname,
+		signature: []interface{}{
+			new(func() (string, error)),
+		},
+	},
 }
 
 //go 1.20 "CutPrefix":              strings.CutPrefix,

pkg/exprhelpers/helpers.go

@@ -595,3 +595,11 @@ func B64Decode(params ...any) (any, error) {
 	}
 	return string(decoded), nil
 }
+
+func Hostname(params ...any) (any, error) {
+	hostname, err := os.Hostname()
+	if err != nil {
+		return "", err
+	}
+	return hostname, nil
+}