[core] PrefixedOverride, ToUpper/ToLower in template system

Author: teo

apricot/local/service.go

@@ -254,7 +254,7 @@ func (s *Service) GetAndProcessComponentConfiguration(query *componentcfg.Query,
 	}
 
 	// Add custom functions to bindings:
-	funcMap := template.MakeStrOperationFuncMap()
+	funcMap := template.MakeStrOperationFuncMap(varStack)
 	for k, v := range funcMap {
 		bindings[k] = v
 	}

configuration/template/fields.go

@@ -189,7 +189,7 @@ func (vs *VarStack) consolidated(stage Stage) (consolidatedStack map[string]stri
 
 func (fields Fields) Execute(confSvc ConfigurationService, parentPath string, varStack map[string]string, objStack map[string]interface{}, stringTemplateCache map[string]template.Template) (err error) {
 	environment := make(map[string]interface{}, len(varStack))
-	strOpStack := MakeStrOperationFuncMap()
+	strOpStack := MakeStrOperationFuncMap(varStack)
 	for k, v := range varStack {
 		environment[k] = v
 	}

configuration/template/stack.go

@@ -141,7 +141,7 @@ func MakeToPtreeFunc(varStack map[string]string, propMap map[string]string) ToPt
 	}
 }
 
-func MakeStrOperationFuncMap() map[string]interface{} {
+func MakeStrOperationFuncMap(varStack map[string]string) map[string]interface{} {
 	return map[string]interface{}{
 		"Atoi": func(in string) (out int) {
 			var err error
@@ -164,6 +164,14 @@ func MakeStrOperationFuncMap() map[string]interface{} {
 			out = strings.TrimSpace(in)
 			return
 		},
+		"ToUpper": func(in string) (out string) {
+			out = strings.ToUpper(in)
+			return
+		},
+		"ToLower": func(in string) (out string) {
+			out = strings.ToLower(in)
+			return
+		},
 		"FromJson": func(in string) (out interface{}) {
 			bytes := []byte(in)
 			err := json.Unmarshal(bytes, &out)
@@ -190,5 +198,27 @@ func MakeStrOperationFuncMap() map[string]interface{} {
 		"NewID": func() (out string) {
 			return uid.New().String()
 		},
+		"PrefixedOverride": func(varname, prefix string) (out string) {
+			prefixed, prefixedOk := varStack[prefix + "_" + varname]
+			fallback, fallbackOk := varStack[varname]
+
+			// Handle explicit null values
+			if prefixedOk && (prefixed == "none" || len(strings.TrimSpace(prefixed)) == 0) {
+				prefixedOk = false
+			}
+			if fallbackOk && (fallback == "none" || len(strings.TrimSpace(fallback)) == 0) {
+				fallbackOk = false
+			}
+
+			if !prefixedOk {
+				if fallbackOk {
+					return fallback
+				}
+				return "" // Neither value exists
+			}
+
+			// prefixedOk is true, fallbackOk we don't know & don't care at this point
+			return prefixed
+		},
 	}
 }