Use html/template for console templates and add template libary support.

Add a function to bypass the new auto-escaping.
Add a function to workaround go's templates only allowing passing in one argument.

Change-Id: Id7aa3f95e7c227692dc22108388b1d9b1e2eec99

rules/manager/manager.go

@@ -137,7 +137,8 @@ func (m *ruleManager) queueAlertNotifications(rule *rules.AlertingRule, timestam
 		defs := "{{$labels := .Labels}}{{$value := .Value}}"
 
 		expand := func(text string) string {
-			result, err := templates.Expand(defs+text, "__alert_"+rule.Name(), tmplData, timestamp, m.storage)
+			template := templates.NewTemplateExpander(defs+text, "__alert_"+rule.Name(), tmplData, timestamp, m.storage)
+			result, err := template.Expand()
 			if err != nil {
 				result = err.Error()
 				glog.Warningf("Error expanding alert template %v with data '%v': %v", rule.Name(), tmplData, err)

templates/templates.go

@@ -21,7 +21,9 @@ import (
 	"regexp"
 	"sort"
 	"strings"
-	"text/template"
+
+	html_template "html/template"
+	text_template "text/template"
 
 	clientmodel "github.com/prometheus/client_golang/model"
 
@@ -55,22 +57,46 @@ func (q queryResultByLabelSorter) Swap(i, j int) {
 	q.results[i], q.results[j] = q.results[j], q.results[i]
 }
 
-// Expand a template, using the given data, time and storage.
-func Expand(text string, name string, data interface{}, timestamp clientmodel.Timestamp, storage metric.PreloadingPersistence) (result string, resultErr error) {
-
-	// It'd better to have no alert description than to kill the whole process
-	// if there's a bug in the template. Similarly with console templates.
-	defer func() {
-		if r := recover(); r != nil {
-			var ok bool
-			resultErr, ok = r.(error)
-			if !ok {
-				resultErr = fmt.Errorf("Panic expanding template: %v", r)
+func query(q string, timestamp clientmodel.Timestamp, storage metric.PreloadingPersistence) (queryResult, error) {
+	exprNode, err := rules.LoadExprFromString(q)
+	if err != nil {
+		return nil, err
 	}
+	queryStats := stats.NewTimerGroup()
+	vector, err := ast.EvalToVector(exprNode, timestamp, storage, queryStats)
+	if err != nil {
+		return nil, err
 	}
-	}()
 
-	funcMap := template.FuncMap{
+	// ast.Vector is hard to work with in templates, so convert to
+	// base data types.
+	var result = make(queryResult, len(vector))
+	for n, v := range vector {
+		s := sample{
+			Value:  float64(v.Value),
+			Labels: make(map[string]string),
+		}
+		for label, value := range v.Metric {
+			s.Labels[string(label)] = string(value)
+		}
+		result[n] = &s
+	}
+	return result, nil
+}
+
+type templateExpander struct {
+	text    string
+	name    string
+	data    interface{}
+	funcMap text_template.FuncMap
+}
+
+func NewTemplateExpander(text string, name string, data interface{}, timestamp clientmodel.Timestamp, storage metric.PreloadingPersistence) *templateExpander {
+	return &templateExpander{
+		text: text,
+		name: name,
+		data: data,
+		funcMap: text_template.FuncMap{
 			"query": func(q string) (queryResult, error) {
 				return query(q, timestamp, storage)
 			},
@@ -89,10 +115,20 @@ func Expand(text string, name string, data interface{}, timestamp clientmodel.Ti
 			"strvalue": func(s *sample) string {
 				return s.Labels["__value__"]
 			},
+			"args": func(args ...interface{}) map[string]interface{} {
+				result := make(map[string]interface{})
+				for i, a := range args {
+					result[fmt.Sprintf("arg%d", i)] = a
+				}
+				return result
+			},
 			"reReplaceAll": func(pattern, repl, text string) string {
 				re := regexp.MustCompile(pattern)
 				return re.ReplaceAllString(text, repl)
 			},
+			"safeHtml": func(text string) html_template.HTML {
+				return html_template.HTML(text)
+			},
 			"match": regexp.MatchString,
 			"title": strings.Title,
 			"sortByLabel": func(label string, v queryResult) queryResult {
@@ -140,43 +176,62 @@ func Expand(text string, name string, data interface{}, timestamp clientmodel.Ti
 				}
 				return fmt.Sprintf("%.4g %s", v, prefix)
 			},
+		},
+	}
 }
 
-	var buffer bytes.Buffer
-	tmpl, err := template.New(name).Funcs(funcMap).Parse(text)
-	if err != nil {
-		return "", fmt.Errorf("Error parsing template %v: %v", name, err)
+// Expand a template.
+func (te templateExpander) Expand() (result string, resultErr error) {
+	// It'd better to have no alert description than to kill the whole process
+	// if there's a bug in the template.
+	defer func() {
+		if r := recover(); r != nil {
+			var ok bool
+			resultErr, ok = r.(error)
+			if !ok {
+				resultErr = fmt.Errorf("Panic expanding template %v: %v", te.name, r)
 			}
-	err = tmpl.Execute(&buffer, data)
+		}
+	}()
+
+	var buffer bytes.Buffer
+	tmpl, err := text_template.New(te.name).Funcs(te.funcMap).Parse(te.text)
 	if err != nil {
-		return "", fmt.Errorf("Error executing template %v: %v", name, err)
+		return "", fmt.Errorf("Error parsing template %v: %v", te.name, err)
+	}
+	err = tmpl.Execute(&buffer, te.data)
+	if err != nil {
+		return "", fmt.Errorf("Error executing template %v: %v", te.name, err)
 	}
 	return buffer.String(), nil
 }
 
-func query(q string, timestamp clientmodel.Timestamp, storage metric.PreloadingPersistence) (queryResult, error) {
-	exprNode, err := rules.LoadExprFromString(q)
-	if err != nil {
-		return nil, err
+// Expand a template with HTML escaping, with templates read from the given files.
+func (te templateExpander) ExpandHTML(templateFiles []string) (result string, resultErr error) {
+	defer func() {
+		if r := recover(); r != nil {
+			var ok bool
+			resultErr, ok = r.(error)
+			if !ok {
+				resultErr = fmt.Errorf("Panic expanding template %v: %v", te.name, r)
 			}
-	queryStats := stats.NewTimerGroup()
-	vector, err := ast.EvalToVector(exprNode, timestamp, storage, queryStats)
-	if err != nil {
-		return nil, err
 		}
+	}()
 
-	// ast.Vector is hard to work with in templates, so convert to
-	// base data types.
-	var result = make(queryResult, len(vector))
-	for n, v := range vector {
-		s := sample{
-			Value:  float64(v.Value),
-			Labels: make(map[string]string),
+	var buffer bytes.Buffer
+	tmpl, err := html_template.New(te.name).Funcs(html_template.FuncMap(te.funcMap)).Parse(te.text)
+	if err != nil {
+		return "", fmt.Errorf("Error parsing template %v: %v", te.name, err)
 	}
-		for label, value := range v.Metric {
-			s.Labels[string(label)] = string(value)
+	if len(templateFiles) > 0 {
+		_, err = tmpl.ParseFiles(templateFiles...)
+		if err != nil {
+			return "", fmt.Errorf("Error parsing template files for %v: %v", te.name, err)
 		}
-		result[n] = &s
 	}
-	return result, nil
+	err = tmpl.Execute(&buffer, te.data)
+	if err != nil {
+		return "", fmt.Errorf("Error executing template %v: %v", te.name, err)
+	}
+	return buffer.String(), nil
 }

templates/templates_test.go

@@ -25,6 +25,7 @@ type testTemplatesScenario struct {
 	text       string
 	output     string
 	shouldFail bool
+	html       bool
 }
 
 func TestTemplateExpansion(t *testing.T) {
@@ -39,6 +40,28 @@ func TestTemplateExpansion(t *testing.T) {
 			text:   "{{ 1 }}",
 			output: "1",
 		},
+		{
+			// HTML escaping.
+			text:   "{{ \"<b>\" }}",
+			output: "&lt;b&gt;",
+			html:   true,
+		},
+		{
+			// Disabling HTML escaping.
+			text:   "{{ \"<b>\" | safeHtml }}",
+			output: "<b>",
+			html:   true,
+		},
+		{
+			// HTML escaping doesn't apply to non-html.
+			text:   "{{ \"<b>\" }}",
+			output: "<b>",
+		},
+		{
+			// Pass multiple arguments to templates.
+			text:   "{{define \"x\"}}{{.arg0}} {{.arg1}}{{end}}{{template \"x\" (args 1 \"2\")}}",
+			output: "1 2",
+		},
 		{
 			// Get value from query.
 			text:   "{{ query \"metric{instance='a'}\" | first | value }}",
@@ -120,7 +143,14 @@ func TestTemplateExpansion(t *testing.T) {
 	})
 
 	for _, s := range scenarios {
-		result, err := Expand(s.text, "test", nil, time, ts)
+		var result string
+		var err error
+		expander := NewTemplateExpander(s.text, "test", nil, time, ts)
+		if s.html {
+			result, err = expander.ExpandHTML(nil)
+		} else {
+			result, err = expander.Expand()
+		}
 		if s.shouldFail {
 			if err == nil {
 				t.Fatalf("Error not returned from %v", s.text)

web/consoles.go

@@ -19,6 +19,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"path/filepath"
 
 	clientmodel "github.com/prometheus/client_golang/model"
 	"github.com/prometheus/prometheus/storage/metric"
@@ -27,6 +28,7 @@ import (
 
 var (
 	consoleTemplatesPath = flag.String("consoleTemplates", "consoles", "Path to console template directory, available at /console")
+	consoleLibrariesPath = flag.String("consoleLibraries", "console_libraries", "Path to console library directory")
 )
 
 type ConsolesHandler struct {
@@ -64,8 +66,13 @@ func (h *ConsolesHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		Params:    params,
 	}
 
-	now := clientmodel.Now()
-	result, err := templates.Expand(string(text), "__console_"+r.URL.Path, data, now, h.Storage)
+	template := templates.NewTemplateExpander(string(text), "__console_"+r.URL.Path, data, clientmodel.Now(), h.Storage)
+	filenames, err := filepath.Glob(*consoleLibrariesPath + "/*.lib")
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	result, err := template.ExpandHTML(filenames)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return