Support .tpl extensions for values files (#168)

For users who are more accustomed to go templates from helm itself.

pkg/manifests/template/helm.go

@@ -182,10 +182,16 @@ func (h *helm) valuesFile(svc *console.GetServiceDeploymentForAgent_ServiceDeplo
 
 		if strings.HasSuffix(filename, ".liquid") {
 			data, err = renderLiquid(data, svc)
-			if err != nil {
-				return nil, err
-			}
 		}
+
+		if strings.HasSuffix(filename, ".tpl") {
+			data, err = renderTpl(data, svc)
+		}
+
+		if err != nil {
+			return nil, err
+		}
+
 		if err := yaml.Unmarshal(data, &currentMap); err != nil {
 			return nil, errors.Wrapf(err, "failed to parse %s", filename)
 		}

pkg/manifests/template/tpl.go

@@ -0,0 +1,26 @@
+package template
+
+import (
+	"bytes"
+	"text/template"
+
+	"github.com/Masterminds/sprig/v3"
+	console "github.com/pluralsh/console-client-go"
+)
+
+func renderTpl(input []byte, svc *console.GetServiceDeploymentForAgent_ServiceDeployment) ([]byte, error) {
+	bindings := map[string]interface{}{
+		"Configuration": configMap(svc),
+		"Cluster":       clusterConfiguration(svc.Cluster),
+		"Contexts":      contexts(svc),
+	}
+
+	tpl, err := template.New("gotpl").Funcs(sprig.TxtFuncMap()).Parse(string(input))
+	if err != nil {
+		return nil, err
+	}
+
+	var buffer bytes.Buffer
+	err = tpl.Execute(&buffer, bindings)
+	return buffer.Bytes(), err
+}