diff --git a/pkg/config/externalname.go b/pkg/config/externalname.go
index 9eb69f0f..ae9859df 100644
--- a/pkg/config/externalname.go
+++ b/pkg/config/externalname.go
@@ -85,12 +85,21 @@ func ParameterAsIdentifier(param string) ExternalName {
 //
 //	It is required to use this as part of the template.
 //
+// The following template functions are available:
+// ToLower: Converts the contents of the pipeline to lower-case
+// ToUpper: Converts the contents of the pipeline to upper-case
+// Please note that it's currently *not* possible to use
+// the template functions in a pipeline involving the .external_name variable.
 // Example usages:
-// TemplatedStringAsIdentifier("index_name", "/subscriptions/{{ .terraformProviderConfig.subscription }}/{{ .external_name }}")
-// TemplatedStringAsIdentifier("index.name", "/resource/{{ .external_name }}/static")
-// TemplatedStringAsIdentifier("index.name", "{{ .parameters.cluster_id }}:{{ .parameters.node_id }}:{{ .external_name }}")
+// TemplatedStringAsIdentifier("index_name", "/subscriptions/{{ .setup.configuration.subscription }}/{{ .external_name }}")
+// TemplatedStringAsIdentifier("index_name", "/resource/{{ .external_name }}/static")
+// TemplatedStringAsIdentifier("index_name", "{{ .parameters.cluster_id }}:{{ .parameters.node_id }}:{{ .external_name }}")
+// TemplatedStringAsIdentifier("", "arn:aws:network-firewall:{{ .setup.configuration.region }}:{{ .setup.client_metadata.account_id }}:{{ .parameters.type | ToLower }}-rulegroup/{{ .external_name }}")
 func TemplatedStringAsIdentifier(nameFieldPath, tmpl string) ExternalName {
-	t, err := template.New("getid").Parse(tmpl)
+	t, err := template.New("getid").Funcs(template.FuncMap{
+		"ToLower": strings.ToLower,
+		"ToUpper": strings.ToUpper,
+	}).Parse(tmpl)
 	if err != nil {
 		panic(errors.Wrap(err, "cannot parse template"))
 	}
diff --git a/pkg/config/externalname_test.go b/pkg/config/externalname_test.go
index 54d86a56..52f7ae0d 100644
--- a/pkg/config/externalname_test.go
+++ b/pkg/config/externalname_test.go
@@ -223,6 +223,42 @@ func TestTemplatedGetIDFn(t *testing.T) {
 				id: "olala/paramval:myname/configval",
 			},
 		},
+		"TemplateFunctionToLower": {
+			reason: "Should work with a call of ToLower.",
+			args: args{
+				tmpl:         "olala/{{ .parameters.ola | ToLower }}:{{ .external_name }}/{{ .setup.configuration.oma | ToLower }}",
+				externalName: "myname",
+				parameters: map[string]any{
+					"ola": "ALL_CAPITAL",
+				},
+				setup: map[string]any{
+					"configuration": map[string]any{
+						"oma": "CamelCase",
+					},
+				},
+			},
+			want: want{
+				id: "olala/all_capital:myname/camelcase",
+			},
+		},
+		"TemplateFunctionToUpper": {
+			reason: "Should work with a call of ToUpper.",
+			args: args{
+				tmpl:         "olala/{{ .parameters.ola | ToUpper }}:{{ .external_name }}/{{ .setup.configuration.oma | ToUpper }}",
+				externalName: "myname",
+				parameters: map[string]any{
+					"ola": "all_small",
+				},
+				setup: map[string]any{
+					"configuration": map[string]any{
+						"oma": "CamelCase",
+					},
+				},
+			},
+			want: want{
+				id: "olala/ALL_SMALL:myname/CAMELCASE",
+			},
+		},
 	}
 	for n, tc := range cases {
 		t.Run(n, func(t *testing.T) {