PR #154: Make route metric names configurable

This patch makes the metric names for the service routes
configurable by using a template to generate them.

config/config.go

@@ -70,6 +70,7 @@ type Runtime struct {
 type Metrics struct {
 	Target           string
 	Prefix           string
+	Names            string
 	Interval         time.Duration
 	GraphiteAddr     string
 	StatsDAddr       string

config/default.go

@@ -41,6 +41,7 @@ var Default = &Config{
 	},
 	Metrics: Metrics{
 		Prefix:         "default",
+		Names:          "{{clean .Service}}.{{clean .Host}}.{{clean .Path}}.{{clean .TargetURL.Host}}",
 		Interval:       30 * time.Second,
 		CirconusAPIApp: "fabio",
 	},

config/load.go

@@ -107,6 +107,7 @@ func load(p *properties.Properties) (cfg *Config, err error) {
 	f.DurationVar(&cfg.Proxy.FlushInterval, "proxy.flushinterval", Default.Proxy.FlushInterval, "flush interval for streaming responses")
 	f.StringVar(&cfg.Metrics.Target, "metrics.target", Default.Metrics.Target, "metrics backend")
 	f.StringVar(&cfg.Metrics.Prefix, "metrics.prefix", Default.Metrics.Prefix, "prefix for reported metrics")
+	f.StringVar(&cfg.Metrics.Names, "metrics.names", Default.Metrics.Names, "route metric name template")
 	f.DurationVar(&cfg.Metrics.Interval, "metrics.interval", Default.Metrics.Interval, "metrics reporting interval")
 	f.StringVar(&cfg.Metrics.GraphiteAddr, "metrics.graphite.addr", Default.Metrics.GraphiteAddr, "graphite server address")
 	f.StringVar(&cfg.Metrics.StatsDAddr, "metrics.statsd.addr", Default.Metrics.StatsDAddr, "statsd server address")

config/load_test.go

@@ -45,6 +45,7 @@ registry.consul.register.checkTimeout = 10s
 registry.consul.service.status = a,b
 metrics.target = graphite
 metrics.prefix = someprefix
+metrics.names = {{clean .Service}}.{{clean .Host}}.{{clean .Path}}.{{clean .TargetURL.Host}}
 metrics.interval = 5s
 metrics.graphite.addr = 5.6.7.8:9999
 metrics.statsd.addr = 6.7.8.9:9999
@@ -125,6 +126,7 @@ aws.apigw.cert.cn = furb
 		Metrics: Metrics{
 			Target:           "graphite",
 			Prefix:           "someprefix",
+			Names:            "{{clean .Service}}.{{clean .Host}}.{{clean .Path}}.{{clean .TargetURL.Host}}",
 			Interval:         5 * time.Second,
 			GraphiteAddr:     "5.6.7.8:9999",
 			StatsDAddr:       "6.7.8.9:9999",

fabio.properties

@@ -490,6 +490,40 @@
 # metrics.prefix = default
 
 
+# metrics.names configures the template for the route metric names.
+# The value is expanded by the text/template package and provides
+# the following variables:
+#
+#  - Service:   the service name
+#  - Host:      the host part of the URL prefix
+#  - Path:      the path part of the URL prefix
+#  - TargetURL: the URL of the target
+#
+# The following additional functions are defined:
+#
+#  - clean:     lowercase value and replace '.' and ':' with '_'
+#
+# Given a route rule of
+#
+#  route add testservice www.example.com/ http://10.1.2.3:12345/
+#
+# the template variables are:
+#
+#  .Service = testservice
+#  .Host = www.example.com
+#  .Path  = /
+#  .TargetURL.Host = 10.1.2.3:12345
+#
+# which results to the following metric name when using the
+# default template:
+#
+#  testservice.www_example_com./.10_1_2_3_12345
+#
+# The default is
+#
+# metrics.names = {{clean .Service}}.{{clean .Host}}.{{clean .Path}}.{{clean .TargetURL.Host}}
+
+
 # metrics.interval configures the interval in which metrics are
 # reported.
 #

metrics/metrics.go

@@ -6,11 +6,14 @@
 package metrics
 
 import (
+	"bytes"
+	"fmt"
 	"log"
 	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
+	"text/template"
 
 	"github.com/eBay/fabio/config"
 	"github.com/eBay/fabio/exit"
@@ -19,13 +22,31 @@ import (
 // DefaultRegistry stores the metrics library provider.
 var DefaultRegistry Registry = NoopRegistry{}
 
+// DefaultNames contains the default template for route metric names.
+const DefaultNames = "{{clean .Service}}.{{clean .Host}}.{{clean .Path}}.{{clean .TargetURL.Host}}"
+
+// names stores the template for the route metric names.
+var names *template.Template
+
+func init() {
+	// make sure names is initialized to something
+	var err error
+	if names, err = parseNames(DefaultNames); err != nil {
+		panic(err)
+	}
+}
+
 // NewRegistry creates a new metrics registry.
 func NewRegistry(cfg config.Metrics) (r Registry, err error) {
 	prefix := cfg.Prefix
 	if prefix == "default" {
 		prefix = defaultPrefix()
 	}
 
+	if names, err = parseNames(cfg.Names); err != nil {
+		return nil, fmt.Errorf("metrics: invalid names template. %s", err)
+	}
+
 	switch cfg.Target {
 	case "stdout":
 		log.Printf("[INFO] Sending metrics to stdout")
@@ -54,14 +75,43 @@ func NewRegistry(cfg config.Metrics) (r Registry, err error) {
 	panic("unreachable")
 }
 
+// parseNames parses the route metric name template.
+func parseNames(tmpl string) (*template.Template, error) {
+	funcMap := template.FuncMap{
+		"clean": clean,
+	}
+	t, err := template.New("names").Funcs(funcMap).Parse(tmpl)
+	if err != nil {
+		return nil, err
+	}
+	testURL, err := url.Parse("http://127.0.0.1:12345/")
+	if err != nil {
+		return nil, err
+	}
+	if _, err := TargetName("testservice", "test.example.com", "/test", testURL); err != nil {
+		return nil, err
+	}
+	return t, nil
+}
+
 // TargetName returns the metrics name from the given parameters.
-func TargetName(service, host, path string, targetURL *url.URL) string {
-	return strings.Join([]string{
-		clean(service),
-		clean(host),
-		clean(path),
-		clean(targetURL.Host),
-	}, ".")
+func TargetName(service, host, path string, targetURL *url.URL) (string, error) {
+	if names == nil {
+		return "", nil
+	}
+
+	var name bytes.Buffer
+
+	data := struct {
+		Service, Host, Path string
+		TargetURL           *url.URL
+	}{service, host, path, targetURL}
+
+	if err := names.Execute(&name, data); err != nil {
+		return "", err
+	}
+
+	return name.String(), nil
 }
 
 // clean creates safe names for graphite reporting by replacing

metrics/metrics_test.go

@@ -32,7 +32,12 @@ func TestTargetName(t *testing.T) {
 		if err != nil {
 			t.Fatalf("%d: %v", i, err)
 		}
-		if got, want := TargetName(tt.service, tt.host, tt.path, u), tt.name; got != want {
+
+		got, err := TargetName(tt.service, tt.host, tt.path, u)
+		if err != nil {
+			t.Fatalf("%d: %v", i, err)
+		}
+		if want := tt.name; got != want {
 			t.Errorf("%d: got %q want %q", i, got, want)
 		}
 	}

route/route.go

@@ -2,6 +2,7 @@ package route
 
 import (
 	"fmt"
+	"log"
 	"net/url"
 	"sort"
 	"strings"
@@ -46,7 +47,11 @@ func (r *Route) addTarget(service string, targetURL *url.URL, fixedWeight float6
 		fixedWeight = 0
 	}
 
-	name := metrics.TargetName(service, r.Host, r.Path, targetURL)
+	name, err := metrics.TargetName(service, r.Host, r.Path, targetURL)
+	if err != nil {
+		log.Printf("[ERROR] Invalid metrics name: %s", err)
+		name = "unknown"
+	}
 	timer := ServiceRegistry.GetTimer(name)
 
 	t := &Target{Service: service, Tags: tags, URL: targetURL, FixedWeight: fixedWeight, Timer: timer, timerName: name}