Move template functionality out of target.

The target implementation and interface contain methods only serving a
specific purpose of the templates. They were moved to the template
as they operate on more fundamental target data.

retrieval/target.go

@@ -19,7 +19,6 @@ import (
 	"math/rand"
 	"net/http"
 	"net/url"
-	"os"
 	"strings"
 	"sync"
 	"time"
@@ -53,8 +52,6 @@ const (
 var (
 	errIngestChannelFull = errors.New("ingestion channel full")
 
-	localhostRepresentations = []string{"127.0.0.1", "localhost"}
-
 	targetIntervalLength = prometheus.NewSummaryVec(
 		prometheus.SummaryOpts{
 			Namespace:  namespace,
@@ -118,17 +115,11 @@ type Target interface {
 	URL() string
 	// Used to populate the `instance` label in metrics.
 	InstanceIdentifier() string
-	// The URL as seen from other hosts. References to localhost are resolved
-	// to the address of the prometheus server.
-	GlobalURL() string
 	// Return the labels describing the targets. These are the base labels
 	// as well as internal labels.
-	Labels() clientmodel.LabelSet
+	fullLabels() clientmodel.LabelSet
 	// Return the target's base labels.
 	BaseLabels() clientmodel.LabelSet
-	// Return the target's base labels without job and instance label. That's
-	// useful for display purposes.
-	BaseLabelsWithoutJobAndInstance() clientmodel.LabelSet
 	// Start scraping the target in regular intervals.
 	RunScraper(storage.SampleAppender)
 	// Stop scraping, synchronous.
@@ -195,7 +186,6 @@ type target struct {
 
 	// The status object for the target. It is only set once on initialization.
 	status *TargetStatus
-
 	// The HTTP client used to scrape the target's endpoint.
 	httpClient *http.Client
 
@@ -419,66 +409,43 @@ func (t *target) InstanceIdentifier() string {
 	return t.url.Host
 }
 
-// GlobalURL implements Target.
-func (t *target) GlobalURL() string {
-	url := t.URL()
-
-	hostname, err := os.Hostname()
-	if err != nil {
-		glog.Warningf("Couldn't get hostname: %s, returning target.URL()", err)
-		return url
-	}
-	for _, localhostRepresentation := range localhostRepresentations {
-		url = strings.Replace(url, "//"+localhostRepresentation, "//"+hostname, 1)
-	}
-	return url
-}
-
-// Labels implements Target.
-func (t *target) Labels() clientmodel.LabelSet {
+// fullLabels implements Target.
+func (t *target) fullLabels() clientmodel.LabelSet {
 	t.RLock()
 	defer t.RUnlock()
-	ls := clientmodel.LabelSet{}
+	lset := make(clientmodel.LabelSet, len(t.baseLabels)+2)
 	for ln, lv := range t.baseLabels {
-		ls[ln] = lv
+		lset[ln] = lv
 	}
-	ls[clientmodel.MetricsPathLabel] = clientmodel.LabelValue(t.url.Path)
-	ls[clientmodel.AddressLabel] = clientmodel.LabelValue(t.url.Host)
-	return ls
+	lset[clientmodel.MetricsPathLabel] = clientmodel.LabelValue(t.url.Path)
+	lset[clientmodel.AddressLabel] = clientmodel.LabelValue(t.url.Host)
+	return lset
 }
 
 // BaseLabels implements Target.
 func (t *target) BaseLabels() clientmodel.LabelSet {
 	t.RLock()
 	defer t.RUnlock()
-	return t.baseLabels
-}
-
-// BaseLabelsWithoutJobAndInstance implements Target.
-//
-// TODO(fabxc): This method does not have to be part of the interface. Implement this
-// as a template filter func for the single use case.
-func (t *target) BaseLabelsWithoutJobAndInstance() clientmodel.LabelSet {
-	t.RLock()
-	defer t.RUnlock()
-	ls := clientmodel.LabelSet{}
+	lset := make(clientmodel.LabelSet, len(t.baseLabels))
 	for ln, lv := range t.baseLabels {
-		if ln != clientmodel.JobLabel && ln != clientmodel.InstanceLabel {
-			ls[ln] = lv
-		}
+		lset[ln] = lv
 	}
-	return ls
+	return lset
 }
 
 func (t *target) recordScrapeHealth(sampleAppender storage.SampleAppender, timestamp clientmodel.Timestamp, scrapeDuration time.Duration) {
-	healthMetric := clientmodel.Metric{}
-	durationMetric := clientmodel.Metric{}
-	for label, value := range t.BaseLabels() {
+	t.RLock()
+	healthMetric := make(clientmodel.Metric, len(t.baseLabels)+1)
+	durationMetric := make(clientmodel.Metric, len(t.baseLabels)+1)
+
+	healthMetric[clientmodel.MetricNameLabel] = clientmodel.LabelValue(scrapeHealthMetricName)
+	durationMetric[clientmodel.MetricNameLabel] = clientmodel.LabelValue(scrapeDurationMetricName)
+
+	for label, value := range t.baseLabels {
 		healthMetric[label] = value
 		durationMetric[label] = value
 	}
-	healthMetric[clientmodel.MetricNameLabel] = clientmodel.LabelValue(scrapeHealthMetricName)
-	durationMetric[clientmodel.MetricNameLabel] = clientmodel.LabelValue(scrapeDurationMetricName)
+	t.RUnlock()
 
 	healthValue := clientmodel.SampleValue(0)
 	if t.status.State() == Healthy {

retrieval/target_test.go

@@ -44,13 +44,6 @@ func TestBaseLabels(t *testing.T) {
 	if !reflect.DeepEqual(want, got) {
 		t.Errorf("want base labels %v, got %v", want, got)
 	}
-	delete(want, clientmodel.JobLabel)
-	delete(want, clientmodel.InstanceLabel)
-
-	got = target.BaseLabelsWithoutJobAndInstance()
-	if !reflect.DeepEqual(want, got) {
-		t.Errorf("want base labels %v, got %v", want, got)
-	}
 }
 
 func TestTargetScrapeUpdatesState(t *testing.T) {

retrieval/targetmanager.go

@@ -215,7 +215,7 @@ func (tm *TargetManager) updateTargetGroup(tgroup *config.TargetGroup, cfg *conf
 				// to build up.
 				wg.Add(1)
 				go func(t Target) {
-					match.Update(cfg, t.Labels())
+					match.Update(cfg, t.fullLabels())
 					wg.Done()
 				}(tnew)
 				newTargets[i] = match

web/templates/status.html

@@ -48,7 +48,7 @@
           {{range $pool}}
             <tr>
               <td>
-                <a href="{{.GlobalURL}}">{{.URL}}</a>
+                <a href="{{.URL | globalURL}}">{{.URL}}</a>
               </td>
               <td>
                 <span class="alert alert-{{index $stateToClass .Status.State}} target_status_alert">
@@ -56,7 +56,7 @@
                 </span>
               </td>
               <td>
-                {{.BaseLabelsWithoutJobAndInstance}}
+                {{stripLabels .BaseLabels "job" "instance"}}
               </td>
               <td>
                 {{if .Status.LastScrape.IsZero}}Never{{else}}{{since .Status.LastScrape}} ago{{end}}

web/web.go

@@ -29,10 +29,14 @@ import (
 	"github.com/golang/glog"
 	"github.com/prometheus/client_golang/prometheus"
 
+	clientmodel "github.com/prometheus/client_golang/model"
+
 	"github.com/prometheus/prometheus/web/api"
 	"github.com/prometheus/prometheus/web/blob"
 )
 
+var localhostRepresentations = []string{"127.0.0.1", "localhost"}
+
 // Commandline flags.
 var (
 	listenAddress  = flag.String("web.listen-address", ":9090", "Address to listen on for the web interface, API, and telemetry.")
@@ -150,28 +154,53 @@ func getConsoles(pathPrefix string) string {
 	return ""
 }
 
-func getTemplate(name string, pathPrefix string) (t *template.Template, err error) {
-	t = template.New("_base")
+func getTemplate(name string, pathPrefix string) (*template.Template, error) {
+	t := template.New("_base")
+	var err error
 
 	t.Funcs(template.FuncMap{
 		"since":       time.Since,
 		"getConsoles": func() string { return getConsoles(pathPrefix) },
 		"pathPrefix":  func() string { return pathPrefix },
+		"stripLabels": func(lset clientmodel.LabelSet, labels ...clientmodel.LabelName) clientmodel.LabelSet {
+			for _, ln := range labels {
+				delete(lset, ln)
+			}
+			return lset
+		},
+		"globalURL": func(url string) string {
+			hostname, err := os.Hostname()
+			if err != nil {
+				glog.Warningf("Couldn't get hostname: %s, returning target.URL()", err)
+				return url
+			}
+			for _, localhostRepresentation := range localhostRepresentations {
+				url = strings.Replace(url, "//"+localhostRepresentation, "//"+hostname, 1)
+			}
+			return url
+		},
 	})
+
 	file, err := getTemplateFile("_base")
 	if err != nil {
-		glog.Error("Could not read base template: ", err)
+		glog.Errorln("Could not read base template:", err)
 		return nil, err
 	}
-	t.Parse(file)
+	t, err = t.Parse(file)
+	if err != nil {
+		glog.Errorln("Could not parse base template:", err)
+	}
 
 	file, err = getTemplateFile(name)
 	if err != nil {
-		glog.Error("Could not read base template: ", err)
+		glog.Error("Could not read template %d: ", name, err)
 		return nil, err
 	}
-	t.Parse(file)
-	return
+	t, err = t.Parse(file)
+	if err != nil {
+		glog.Errorf("Could not parse template %s: %s", name, err)
+	}
+	return t, err
 }
 
 func executeTemplate(w http.ResponseWriter, name string, data interface{}, pathPrefix string) {