Merge pull request #5463 from prometheus/beorn7/templating

Follow-up on #5009

cmd/prometheus/main.go

@@ -443,7 +443,11 @@ func main() {
 				}
 				files = append(files, fs...)
 			}
-			return ruleManager.Update(time.Duration(cfg.GlobalConfig.EvaluationInterval), files)
+			return ruleManager.Update(
+				time.Duration(cfg.GlobalConfig.EvaluationInterval),
+				files,
+				cfg.GlobalConfig.ExternalLabels,
+			)
 		},
 	}
 
@@ -747,6 +751,7 @@ func reloadConfig(filename string, logger log.Logger, rls ...func(*config.Config
 	if failed {
 		return errors.Errorf("one or more errors occurred while applying the new configuration (--config.file=%q)", filename)
 	}
+
 	promql.SetDefaultEvaluationInterval(time.Duration(conf.GlobalConfig.EvaluationInterval))
 	level.Info(logger).Log("msg", "Completed loading of configuration file", "filename", filename)
 	return nil

cmd/promtool/http.go

@@ -14,8 +14,6 @@
 package main
 
 import (
-	"context"
-	"net/http"
 	"time"
 
 	"github.com/pkg/errors"
@@ -42,12 +40,6 @@ func newPrometheusHTTPClient(serverURL string) (*prometheusHTTPClient, error) {
 	}, nil
 }
 
-func (c *prometheusHTTPClient) do(req *http.Request) (*http.Response, []byte, error) {
-	ctx, cancel := context.WithTimeout(context.Background(), c.requestTimeout)
-	defer cancel()
-	return c.httpClient.Do(ctx, req)
-}
-
 func (c *prometheusHTTPClient) urlJoin(path string) string {
 	return c.httpClient.URL(path, nil).String()
 }

cmd/promtool/unittest.go

@@ -163,7 +163,8 @@ func (tg *testGroup) test(mint, maxt time.Time, evalInterval time.Duration, grou
 		Logger:     &dummyLogger{},
 	}
 	m := rules.NewManager(opts)
-	groupsMap, ers := m.LoadGroups(tg.Interval, ruleFiles...)
+	// TODO(beorn7): Provide a way to pass in external labels.
+	groupsMap, ers := m.LoadGroups(tg.Interval, nil, ruleFiles...)
 	if ers != nil {
 		return ers
 	}

discovery/openstack/mock_test.go

@@ -247,7 +247,7 @@ func (m *SDMock) HandleHypervisorListSuccessfully() {
 		testHeader(m.t, r, "X-Auth-Token", tokenID)
 
 		w.Header().Add("Content-Type", "application/json")
-		fmt.Fprintf(w, hypervisorListBody)
+		fmt.Fprint(w, hypervisorListBody)
 	})
 }
 
@@ -544,7 +544,7 @@ func (m *SDMock) HandleServerListSuccessfully() {
 		testHeader(m.t, r, "X-Auth-Token", tokenID)
 
 		w.Header().Add("Content-Type", "application/json")
-		fmt.Fprintf(w, serverListBody)
+		fmt.Fprint(w, serverListBody)
 	})
 }
 
@@ -583,6 +583,6 @@ func (m *SDMock) HandleFloatingIPListSuccessfully() {
 		testHeader(m.t, r, "X-Auth-Token", tokenID)
 
 		w.Header().Add("Content-Type", "application/json")
-		fmt.Fprintf(w, listOutput)
+		fmt.Fprint(w, listOutput)
 	})
 }

docs/configuration/alerting_rules.md

@@ -42,9 +42,11 @@ The `annotations` clause specifies a set of informational labels that can be use
 
 #### Templating
 
-Label and annotation values can be templated using [console templates](https://prometheus.io/docs/visualization/consoles).
-The `$labels` variable holds the label key/value pairs of an alert instance
-and `$value` holds the evaluated value of an alert instance.
+Label and annotation values can be templated using [console
+templates](https://prometheus.io/docs/visualization/consoles).  The `$labels`
+variable holds the label key/value pairs of an alert instance. The configured
+external labels can be accessed via the `$externalLabels` variable. The
+`$value` variable holds the evaluated value of an alert instance.
 
     # To insert a firing element's label values:
     {{ $labels.<labelname> }}

docs/configuration/template_reference.md

@@ -89,8 +89,10 @@ parameterize templates, and have a few other differences.
 
 ### Alert field templates
 
-`.Value` and `.Labels` contain the alert value and labels. They are also exposed
-as the `$value` and `$labels` variables for convenience.
+`.Value`, `.Labels`, and `ExternalLabels` contain the alert value, the alert
+labels, and the globally configured external labels, respectively. They are
+also exposed as the `$value`, `$labels`, and `$externalLabels` variables for
+convenience.
 
 ### Console templates
 
@@ -104,7 +106,9 @@ auto-escaping. To bypass the auto-escaping use the `safe*` functions.,
 URL parameters are available as a map in `.Params`. To access multiple URL
 parameters by the same name, `.RawParams` is a map of the list values for each
 parameter. The URL path is available in `.Path`, excluding the `/consoles/`
-prefix.
+prefix. The globally configured external labels are available as
+`.ExternalLabels`. There are also convenience variables for all four:
+`$rawParams`, `$params`, `$path`, and `$externalLabels`.
 
 Consoles also have access to all the templates defined with `{{define
 "templateName"}}...{{end}}` found in `*.lib` files in the directory pointed to

pkg/rulefmt/rulefmt.go

@@ -16,6 +16,7 @@ package rulefmt
 import (
 	"context"
 	"io/ioutil"
+	"strings"
 	"time"
 
 	"github.com/pkg/errors"
@@ -155,12 +156,16 @@ func testTemplateParsing(rl *Rule) (errs []error) {
 	}
 
 	// Trying to parse templates.
-	tmplData := template.AlertTemplateData(make(map[string]string), 0)
-	defs := "{{$labels := .Labels}}{{$value := .Value}}"
+	tmplData := template.AlertTemplateData(map[string]string{}, map[string]string{}, 0)
+	defs := []string{
+		"{{$labels := .Labels}}",
+		"{{$externalLabels := .ExternalLabels}}",
+		"{{$value := .Value}}",
+	}
 	parseTest := func(text string) error {
 		tmpl := template.NewTemplateExpander(
 			context.TODO(),
-			defs+text,
+			strings.Join(append(defs, text), ""),
 			"__alert_"+rl.Alert,
 			tmplData,
 			model.Time(timestamp.FromTime(time.Now())),

promql/parse.go

@@ -326,17 +326,15 @@ var errUnexpected = errors.New("unexpected error")
 // recover is the handler that turns panics into returns from the top level of Parse.
 func (p *parser) recover(errp *error) {
 	e := recover()
-	if e != nil {
-		if _, ok := e.(runtime.Error); ok {
-			// Print the stack trace but do not inhibit the running application.
-			buf := make([]byte, 64<<10)
-			buf = buf[:runtime.Stack(buf, false)]
+	if _, ok := e.(runtime.Error); ok {
+		// Print the stack trace but do not inhibit the running application.
+		buf := make([]byte, 64<<10)
+		buf = buf[:runtime.Stack(buf, false)]
 
-			fmt.Fprintf(os.Stderr, "parser panic: %v\n%s", e, buf)
-			*errp = errUnexpected
-		} else {
-			*errp = e.(error)
-		}
+		fmt.Fprintf(os.Stderr, "parser panic: %v\n%s", e, buf)
+		*errp = errUnexpected
+	} else if e != nil {
+		*errp = e.(error)
 	}
 	p.lex.close()
 }

rules/alerting.go

@@ -17,6 +17,7 @@ import (
 	"context"
 	"fmt"
 	"net/url"
+	"strings"
 	"sync"
 	"time"
 
@@ -119,6 +120,8 @@ type AlertingRule struct {
 	labels labels.Labels
 	// Non-identifying key/value pairs.
 	annotations labels.Labels
+	// External labels from the global config.
+	externalLabels map[string]string
 	// true if old state has been restored. We start persisting samples for ALERT_FOR_STATE
 	// only after the restoration.
 	restored bool
@@ -140,17 +143,27 @@ type AlertingRule struct {
 }
 
 // NewAlertingRule constructs a new AlertingRule.
-func NewAlertingRule(name string, vec promql.Expr, hold time.Duration, lbls, anns labels.Labels, restored bool, logger log.Logger) *AlertingRule {
+func NewAlertingRule(
+	name string, vec promql.Expr, hold time.Duration,
+	labels, annotations, externalLabels labels.Labels,
+	restored bool, logger log.Logger,
+) *AlertingRule {
+	el := make(map[string]string, len(externalLabels))
+	for _, lbl := range externalLabels {
+		el[lbl.Name] = lbl.Value
+	}
+
 	return &AlertingRule{
-		name:         name,
-		vector:       vec,
-		holdDuration: hold,
-		labels:       lbls,
-		annotations:  anns,
-		health:       HealthUnknown,
-		active:       map[uint64]*Alert{},
-		logger:       logger,
-		restored:     restored,
+		name:           name,
+		vector:         vec,
+		holdDuration:   hold,
+		labels:         labels,
+		annotations:    annotations,
+		externalLabels: el,
+		health:         HealthUnknown,
+		active:         map[uint64]*Alert{},
+		logger:         logger,
+		restored:       restored,
 	}
 }
 
@@ -305,15 +318,19 @@ func (r *AlertingRule) Eval(ctx context.Context, ts time.Time, query QueryFunc,
 			l[lbl.Name] = lbl.Value
 		}
 
-		tmplData := template.AlertTemplateData(l, smpl.V)
+		tmplData := template.AlertTemplateData(l, r.externalLabels, smpl.V)
 		// Inject some convenience variables that are easier to remember for users
 		// who are not used to Go's templating system.
-		defs := "{{$labels := .Labels}}{{$value := .Value}}"
+		defs := []string{
+			"{{$labels := .Labels}}",
+			"{{$externalLabels := .ExternalLabels}}",
+			"{{$value := .Value}}",
+		}
 
 		expand := func(text string) string {
 			tmpl := template.NewTemplateExpander(
 				ctx,
-				defs+text,
+				strings.Join(append(defs, text), ""),
 				"__alert_"+r.Name(),
 				tmplData,
 				model.Time(timestamp.FromTime(ts)),
@@ -449,7 +466,7 @@ func (r *AlertingRule) ForEachActiveAlert(f func(*Alert)) {
 }
 
 func (r *AlertingRule) sendAlerts(ctx context.Context, ts time.Time, resendDelay time.Duration, interval time.Duration, notifyFunc NotifyFunc) {
-	alerts := make([]*Alert, 0)
+	alerts := []*Alert{}
 	r.ForEachActiveAlert(func(alert *Alert) {
 		if alert.needsSending(ts, resendDelay) {
 			alert.LastSentAt = ts

rules/alerting_test.go

@@ -17,6 +17,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/go-kit/kit/log"
 	"github.com/prometheus/prometheus/pkg/labels"
 	"github.com/prometheus/prometheus/pkg/timestamp"
 	"github.com/prometheus/prometheus/promql"
@@ -26,7 +27,7 @@ import (
 func TestAlertingRuleHTMLSnippet(t *testing.T) {
 	expr, err := promql.ParseExpr(`foo{html="<b>BOLD<b>"}`)
 	testutil.Ok(t, err)
-	rule := NewAlertingRule("testrule", expr, 0, labels.FromStrings("html", "<b>BOLD</b>"), labels.FromStrings("html", "<b>BOLD</b>"), false, nil)
+	rule := NewAlertingRule("testrule", expr, 0, labels.FromStrings("html", "<b>BOLD</b>"), labels.FromStrings("html", "<b>BOLD</b>"), nil, false, nil)
 
 	const want = `alert: <a href="/test/prefix/graph?g0.expr=ALERTS%7Balertname%3D%22testrule%22%7D&g0.tab=1">testrule</a>
 expr: <a href="/test/prefix/graph?g0.expr=foo%7Bhtml%3D%22%3Cb%3EBOLD%3Cb%3E%22%7D&g0.tab=1">foo{html=&#34;&lt;b&gt;BOLD&lt;b&gt;&#34;}</a>
@@ -62,7 +63,7 @@ func TestAlertingRuleLabelsUpdate(t *testing.T) {
 		// If an alert is going back and forth between two label values it will never fire.
 		// Instead, you should write two alerts with constant labels.
 		labels.FromStrings("severity", "{{ if lt $value 80.0 }}critical{{ else }}warning{{ end }}"),
-		nil, true, nil,
+		nil, nil, true, nil,
 	)
 
 	results := []promql.Vector{
@@ -142,3 +143,96 @@ func TestAlertingRuleLabelsUpdate(t *testing.T) {
 		testutil.Equals(t, result, filteredRes)
 	}
 }
+
+func TestAlertingRuleExternalLabelsInTemplate(t *testing.T) {
+	suite, err := promql.NewTest(t, `
+		load 1m
+			http_requests{job="app-server", instance="0"}	75 85 70 70
+	`)
+	testutil.Ok(t, err)
+	defer suite.Close()
+
+	err = suite.Run()
+	testutil.Ok(t, err)
+
+	expr, err := promql.ParseExpr(`http_requests < 100`)
+	testutil.Ok(t, err)
+
+	ruleWithoutExternalLabels := NewAlertingRule(
+		"ExternalLabelDoesNotExist",
+		expr,
+		time.Minute,
+		labels.FromStrings("templated_label", "There are {{ len $externalLabels }} external Labels, of which foo is {{ $externalLabels.foo }}."),
+		nil,
+		nil,
+		true, log.NewNopLogger(),
+	)
+	ruleWithExternalLabels := NewAlertingRule(
+		"ExternalLabelExists",
+		expr,
+		time.Minute,
+		labels.FromStrings("templated_label", "There are {{ len $externalLabels }} external Labels, of which foo is {{ $externalLabels.foo }}."),
+		nil,
+		labels.FromStrings("foo", "bar", "dings", "bums"),
+		true, log.NewNopLogger(),
+	)
+	result := promql.Vector{
+		{
+			Metric: labels.FromStrings(
+				"__name__", "ALERTS",
+				"alertname", "ExternalLabelDoesNotExist",
+				"alertstate", "pending",
+				"instance", "0",
+				"job", "app-server",
+				"templated_label", "There are 0 external Labels, of which foo is .",
+			),
+			Point: promql.Point{V: 1},
+		},
+		{
+			Metric: labels.FromStrings(
+				"__name__", "ALERTS",
+				"alertname", "ExternalLabelExists",
+				"alertstate", "pending",
+				"instance", "0",
+				"job", "app-server",
+				"templated_label", "There are 2 external Labels, of which foo is bar.",
+			),
+			Point: promql.Point{V: 1},
+		},
+	}
+
+	evalTime := time.Unix(0, 0)
+	result[0].Point.T = timestamp.FromTime(evalTime)
+	result[1].Point.T = timestamp.FromTime(evalTime)
+
+	var filteredRes promql.Vector // After removing 'ALERTS_FOR_STATE' samples.
+	res, err := ruleWithoutExternalLabels.Eval(
+		suite.Context(), evalTime, EngineQueryFunc(suite.QueryEngine(), suite.Storage()), nil,
+	)
+	testutil.Ok(t, err)
+	for _, smpl := range res {
+		smplName := smpl.Metric.Get("__name__")
+		if smplName == "ALERTS" {
+			filteredRes = append(filteredRes, smpl)
+		} else {
+			// If not 'ALERTS', it has to be 'ALERTS_FOR_STATE'.
+			testutil.Equals(t, smplName, "ALERTS_FOR_STATE")
+		}
+	}
+
+	res, err = ruleWithExternalLabels.Eval(
+		suite.Context(), evalTime, EngineQueryFunc(suite.QueryEngine(), suite.Storage()), nil,
+	)
+	testutil.Ok(t, err)
+	for _, smpl := range res {
+		smplName := smpl.Metric.Get("__name__")
+		if smplName == "ALERTS" {
+			filteredRes = append(filteredRes, smpl)
+		} else {
+			// If not 'ALERTS', it has to be 'ALERTS_FOR_STATE'.
+			testutil.Equals(t, smplName, "ALERTS_FOR_STATE")
+		}
+	}
+
+	testutil.Equals(t, result, filteredRes)
+}

rules/manager.go

@@ -751,11 +751,11 @@ func (m *Manager) Stop() {
 
 // Update the rule manager's state as the config requires. If
 // loading the new rules failed the old rule set is restored.
-func (m *Manager) Update(interval time.Duration, files []string) error {
+func (m *Manager) Update(interval time.Duration, files []string, externalLabels labels.Labels) error {
 	m.mtx.Lock()
 	defer m.mtx.Unlock()
 
-	groups, errs := m.LoadGroups(interval, files...)
+	groups, errs := m.LoadGroups(interval, externalLabels, files...)
 	if errs != nil {
 		for _, e := range errs {
 			level.Error(m.logger).Log("msg", "loading groups failed", "err", e)
@@ -803,7 +803,9 @@ func (m *Manager) Update(interval time.Duration, files []string) error {
 }
 
 // LoadGroups reads groups from a list of files.
-func (m *Manager) LoadGroups(interval time.Duration, filenames ...string) (map[string]*Group, []error) {
+func (m *Manager) LoadGroups(
+	interval time.Duration, externalLabels labels.Labels, filenames ...string,
+) (map[string]*Group, []error) {
 	groups := make(map[string]*Group)
 
 	shouldRestore := !m.restored
@@ -834,6 +836,7 @@ func (m *Manager) LoadGroups(interval time.Duration, filenames ...string) (map[s
 						time.Duration(r.For),
 						labels.FromMap(r.Labels),
 						labels.FromMap(r.Annotations),
+						externalLabels,
 						m.restored,
 						log.With(m.logger, "alert", r.Alert),
 					))

rules/manager_test.go

@@ -51,7 +51,7 @@ func TestAlertingRule(t *testing.T) {
 		expr,
 		time.Minute,
 		labels.FromStrings("severity", "{{\"c\"}}ritical"),
-		nil, true, nil,
+		nil, nil, true, nil,
 	)
 	result := promql.Vector{
 		{
@@ -192,7 +192,7 @@ func TestForStateAddSamples(t *testing.T) {
 		expr,
 		time.Minute,
 		labels.FromStrings("severity", "{{\"c\"}}ritical"),
-		nil, true, nil,
+		nil, nil, true, nil,
 	)
 	result := promql.Vector{
 		{
@@ -366,7 +366,7 @@ func TestForStateRestore(t *testing.T) {
 		expr,
 		alertForDuration,
 		labels.FromStrings("severity", "critical"),
-		nil, true, nil,
+		nil, nil, true, nil,
 	)
 
 	group := NewGroup("default", "", time.Second, []Rule{rule}, true, opts)
@@ -426,7 +426,7 @@ func TestForStateRestore(t *testing.T) {
 			expr,
 			alertForDuration,
 			labels.FromStrings("severity", "critical"),
-			nil, false, nil,
+			nil, nil, false, nil,
 		)
 		newGroup := NewGroup("default", "", time.Second, []Rule{newRule}, true, opts)
 
@@ -581,12 +581,12 @@ func readSeriesSet(ss storage.SeriesSet) (map[string][]promql.Point, error) {
 func TestCopyState(t *testing.T) {
 	oldGroup := &Group{
 		rules: []Rule{
-			NewAlertingRule("alert", nil, 0, nil, nil, true, nil),
+			NewAlertingRule("alert", nil, 0, nil, nil, nil, true, nil),
 			NewRecordingRule("rule1", nil, nil),
 			NewRecordingRule("rule2", nil, nil),
 			NewRecordingRule("rule3", nil, labels.Labels{{Name: "l1", Value: "v1"}}),
 			NewRecordingRule("rule3", nil, labels.Labels{{Name: "l1", Value: "v2"}}),
-			NewAlertingRule("alert2", nil, 0, labels.Labels{{Name: "l2", Value: "v1"}}, nil, true, nil),
+			NewAlertingRule("alert2", nil, 0, labels.Labels{{Name: "l2", Value: "v1"}}, nil, nil, true, nil),
 		},
 		seriesInPreviousEval: []map[string]labels.Labels{
 			{"a": nil},
@@ -604,10 +604,10 @@ func TestCopyState(t *testing.T) {
 			NewRecordingRule("rule3", nil, labels.Labels{{Name: "l1", Value: "v0"}}),
 			NewRecordingRule("rule3", nil, labels.Labels{{Name: "l1", Value: "v1"}}),
 			NewRecordingRule("rule3", nil, labels.Labels{{Name: "l1", Value: "v2"}}),
-			NewAlertingRule("alert", nil, 0, nil, nil, true, nil),
+			NewAlertingRule("alert", nil, 0, nil, nil, nil, true, nil),
 			NewRecordingRule("rule1", nil, nil),
-			NewAlertingRule("alert2", nil, 0, labels.Labels{{Name: "l2", Value: "v0"}}, nil, true, nil),
-			NewAlertingRule("alert2", nil, 0, labels.Labels{{Name: "l2", Value: "v1"}}, nil, true, nil),
+			NewAlertingRule("alert2", nil, 0, labels.Labels{{Name: "l2", Value: "v0"}}, nil, nil, true, nil),
+			NewAlertingRule("alert2", nil, 0, labels.Labels{{Name: "l2", Value: "v1"}}, nil, nil, true, nil),
 			NewRecordingRule("rule4", nil, nil),
 		},
 		seriesInPreviousEval: make([]map[string]labels.Labels, 8),
@@ -654,7 +654,7 @@ func TestUpdate(t *testing.T) {
 	ruleManager.Run()
 	defer ruleManager.Stop()
 
-	err := ruleManager.Update(10*time.Second, files)
+	err := ruleManager.Update(10*time.Second, files, nil)
 	testutil.Ok(t, err)
 	testutil.Assert(t, len(ruleManager.groups) > 0, "expected non-empty rule groups")
 	for _, g := range ruleManager.groups {
@@ -663,7 +663,7 @@ func TestUpdate(t *testing.T) {
 		}
 	}
 
-	err = ruleManager.Update(10*time.Second, files)
+	err = ruleManager.Update(10*time.Second, files, nil)
 	testutil.Ok(t, err)
 	for _, g := range ruleManager.groups {
 		for _, actual := range g.seriesInPreviousEval {
@@ -699,7 +699,7 @@ func TestNotify(t *testing.T) {
 
 	expr, err := promql.ParseExpr("a > 1")
 	testutil.Ok(t, err)
-	rule := NewAlertingRule("aTooHigh", expr, 0, labels.Labels{}, labels.Labels{}, true, log.NewNopLogger())
+	rule := NewAlertingRule("aTooHigh", expr, 0, labels.Labels{}, labels.Labels{}, nil, true, log.NewNopLogger())
 	group := NewGroup("alert", "", time.Second, []Rule{rule}, true, opts)
 
 	app, _ := storage.Appender()

template/template.go

@@ -28,9 +28,9 @@ import (
 	text_template "text/template"
 
 	"github.com/pkg/errors"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/common/model"
-
 	"github.com/prometheus/prometheus/promql"
 	"github.com/prometheus/prometheus/util/strutil"
 )
@@ -261,13 +261,15 @@ func NewTemplateExpander(
 }
 
 // AlertTemplateData returns the interface to be used in expanding the template.
-func AlertTemplateData(labels map[string]string, value float64) interface{} {
+func AlertTemplateData(labels map[string]string, externalLabels map[string]string, value float64) interface{} {
 	return struct {
-		Labels map[string]string
-		Value  float64
+		Labels         map[string]string
+		ExternalLabels map[string]string
+		Value          float64
 	}{
-		Labels: labels,
-		Value:  value,
+		Labels:         labels,
+		ExternalLabels: externalLabels,
+		Value:          value,
 	}
 }
 

web/api/v1/api_test.go

@@ -142,6 +142,7 @@ func (m rulesRetrieverMock) AlertingRules() []*rules.AlertingRule {
 		time.Second,
 		labels.Labels{},
 		labels.Labels{},
+		labels.Labels{},
 		true,
 		log.NewNopLogger(),
 	)
@@ -151,6 +152,7 @@ func (m rulesRetrieverMock) AlertingRules() []*rules.AlertingRule {
 		time.Second,
 		labels.Labels{},
 		labels.Labels{},
+		labels.Labels{},
 		true,
 		log.NewNopLogger(),
 	)

web/federate_test.go

@@ -28,7 +28,6 @@ import (
 
 var scenarios = map[string]struct {
 	params         string
-	accept         string
 	externalLabels labels.Labels
 	code           int
 	body           string

web/web.go

@@ -541,19 +541,39 @@ func (h *Handler) consoles(w http.ResponseWriter, r *http.Request) {
 	for k, v := range rawParams {
 		params[k] = v[0]
 	}
+
+	externalLabels := map[string]string{}
+	h.mtx.RLock()
+	els := h.config.GlobalConfig.ExternalLabels
+	h.mtx.RUnlock()
+	for _, el := range els {
+		externalLabels[el.Name] = el.Value
+	}
+
+	// Inject some convenience variables that are easier to remember for users
+	// who are not used to Go's templating system.
+	defs := []string{
+		"{{$rawParams := .RawParams }}",
+		"{{$params := .Params}}",
+		"{{$path := .Path}}",
+		"{{$externalLabels := .ExternalLabels}}",
+	}
+
 	data := struct {
-		RawParams url.Values
-		Params    map[string]string
-		Path      string
+		RawParams      url.Values
+		Params         map[string]string
+		Path           string
+		ExternalLabels map[string]string
 	}{
-		RawParams: rawParams,
-		Params:    params,
-		Path:      strings.TrimLeft(name, "/"),
+		RawParams:      rawParams,
+		Params:         params,
+		Path:           strings.TrimLeft(name, "/"),
+		ExternalLabels: externalLabels,
 	}
 
 	tmpl := template.NewTemplateExpander(
 		h.context,
-		string(text),
+		strings.Join(append(defs, string(text)), ""),
 		"__console_"+name,
 		data,
 		h.now(),