feat(engine): add template engine

glide.lock

-hash: 692bf17990973cf424c2dbfda6afee8b7002bbc07aaaa78372eac447fed4c8b0
-updated: 2016-04-11T16:13:14.192550144-06:00
+hash: 1dcbbc192182125021b40497fcf9d52bc643455a3bb03d6cd3458819fcb03dbb
+updated: 2016-04-12T13:27:50.987288211-06:00
 imports:
+- name: github.com/aokoli/goutils
+  version: 9c37978a95bd5c709a15883b6242714ea6709e64
 - name: github.com/codegangsta/cli
   version: 71f57d300dd6a780ac1856c005c4b518cfd498ec
 - name: github.com/golang/protobuf
   version: dda510ac0fd43b39770f22ac6260eb91d377bce3
   subpackages:
   - proto
+- name: github.com/Masterminds/sprig
+  version: 679bb747f11c6ffc3373965988fea8877c40b47b
 - name: github.com/spf13/cobra
   version: 4c05eb1145f16d0e6bb4a3e1b6d769f4713cb41f
   subpackages:

glide.yaml

@@ -7,3 +7,4 @@ import:
 - package: github.com/spf13/cobra
   subpackages:
   - cobra
+- package: github.com/Masterminds/sprig

pkg/engine/doc.go

+/*Package engine implements the Go template engine as a Tiller Engine.
+
+Tiller provides a simple interface for taking a Chart and rendering its templates.
+The 'engine' package implements this interface using Go's built-in 'text/template'
+package.
+*/
+package engine

pkg/engine/engine.go

+package engine
+
+import (
+	"bytes"
+	"fmt"
+	"text/template"
+
+	"github.com/Masterminds/sprig"
+	"github.com/deis/tiller/pkg/hapi"
+)
+
+type Engine struct {
+	FuncMap template.FuncMap
+}
+
+// New creates a new Go template Engine instance.
+//
+// The FuncMap is initialized here. You may modify the FuncMap _prior to_ the
+// first invocation of Render.
+//
+// The FuncMap sets all of the Sprig functions except for those that provide
+// access to the underlying OS (env, expandenv).
+func New() *Engine {
+	f := sprig.TxtFuncMap()
+	delete(f, "env")
+	delete(f, "expandenv")
+	return &Engine{
+		FuncMap: f,
+	}
+}
+
+// Render takes a chart, optional values, and attempts to render the Go templates.
+//
+// Render can be called repeatedly on the same engine.
+//
+// This will look in the chart's 'templates' data (e.g. the 'templates/' directory)
+// and attempt to render the templates there using the values passed in.
+func (e *Engine) Render(chart *hapi.Chart, vals *hapi.Values) (map[string]string, error) {
+	// Uncomment this once the proto files compile.
+	//return render(chart.Chartfile.Name, chart.Templates, vals)
+	return map[string]string{}, nil
+}
+
+func (e *Engine) render(name string, tpls map[string]string, v interface{}) (map[string]string, error) {
+	// Basically, what we do here is start with an empty parent template and then
+	// build up a list of templates -- one for each file. Once all of the templates
+	// have been parsed, we loop through again and execute every template.
+	//
+	// The idea with this process is to make it possible for more complex templates
+	// to share common blocks, but to make the entire thing feel like a file-based
+	// template engine.
+	t := template.New(name)
+	files := []string{}
+	for fname, tpl := range tpls {
+		t = t.New(fname).Funcs(e.FuncMap)
+		if _, err := t.Parse(tpl); err != nil {
+			return map[string]string{}, fmt.Errorf("parse error in %q: %s", fname, err)
+		}
+		files = append(files, fname)
+	}
+
+	rendered := make(map[string]string, len(files))
+	var buf bytes.Buffer
+	for _, file := range files {
+		if err := t.ExecuteTemplate(&buf, file, v); err != nil {
+			return map[string]string{}, fmt.Errorf("render error in %q: %s", file, err)
+		}
+		rendered[file] = buf.String()
+		buf.Reset()
+	}
+
+	return rendered, nil
+}

pkg/engine/engine_test.go

+package engine
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+)
+
+func TestEngine(t *testing.T) {
+	e := New()
+
+	// Forbidden because they allow access to the host OS.
+	forbidden := []string{"env", "expandenv"}
+	for _, f := range forbidden {
+		if _, ok := e.FuncMap[f]; ok {
+			t.Errorf("Forbidden function %s exists in FuncMap.", f)
+		}
+	}
+}
+
+func TestRender(t *testing.T) {
+	t.Skip()
+}
+
+func TestRenderInternals(t *testing.T) {
+	// Test the internals of the rendering tool.
+	e := New()
+
+	tpls := map[string]string{
+		"one": `Hello {{title .Name}}`,
+		"two": `Goodbye {{upper .Value}}`,
+		// Test whether a template can reliably reference another template
+		// without regard for ordering.
+		"three": `{{template "two" dict "Value" "three"}}`,
+	}
+	vals := map[string]string{"Name": "one", "Value": "two"}
+
+	out, err := e.render("irrelevant", tpls, vals)
+	if err != nil {
+		t.Fatalf("Failed template rendering: %s", err)
+	}
+
+	if len(out) != 3 {
+		t.Fatalf("Expected 3 templates, got %d", len(out))
+	}
+
+	if out["one"] != "Hello One" {
+		t.Errorf("Expected 'Hello One', got %q", out["one"])
+	}
+
+	if out["two"] != "Goodbye TWO" {
+		t.Errorf("Expected 'Goodbye TWO'. got %q", out["two"])
+	}
+
+	if out["three"] != "Goodbye THREE" {
+		t.Errorf("Expected 'Goodbye THREE'. got %q", out["two"])
+	}
+}
+
+func TestParallelRenderInternals(t *testing.T) {
+	// Make sure that we can use one Engine to run parallel template renders.
+	e := New()
+	var wg sync.WaitGroup
+	for i := 0; i < 20; i++ {
+		wg.Add(1)
+		go func(i int) {
+			fname := "my/file/name"
+			tt := fmt.Sprintf("expect-%d", i)
+			tpls := map[string]string{fname: `{{.val}}`}
+			v := map[string]string{"val": tt}
+			out, err := e.render("intentionally_duplicated", tpls, v)
+			if err != nil {
+				t.Errorf("Failed to render %s: %s", tt, err)
+			}
+			if out[fname] != tt {
+				t.Errorf("Expected %q, got %q", tt, out[fname])
+			}
+			wg.Done()
+		}(i)
+	}
+	wg.Wait()
+}