metric ignore list

closes #3

README.org

@@ -77,6 +77,11 @@ Optionall, it also supports:
   this metric if the fetch failed and a ~0~ otherwise. In other words,
   this can be a simple availability check. If this isn't set, it will
   simply ignore failed fetches.
+- ~IgnoreMetrics~ - a list of metric names (corresponding to keys in
+  the expvar JSON) that will just be ignored and not passed along to
+  graphite. Handy if there are metrics that you just don't care about
+  and would rather that they don't take up space on your graphite
+  server.
 
 ~CheckInterval~ and ~Timeout~ can also be individually overridden for
 each endpoint as well.

endpoint.go

@@ -24,6 +24,7 @@ type endpoint struct {
 	failureMetric  string
 	checkInterval  int
 	timeout        int
+	ignoreMetrics  map[string]struct{}
 	graphiteServer Submitable
 	fetcher        fetcher
 	logger         log.Logger
@@ -34,20 +35,28 @@ type metric struct {
 	Value float64
 }
 
-func newEndpoint(c endpointconfig, interval int, timeout int, g Submitable, fetcher fetcher, logger log.Logger) *endpoint {
+func newEndpoint(c endpointconfig, interval int, timeout int, ignoreMetrics []string, g Submitable, fetcher fetcher, logger log.Logger) *endpoint {
 	if c.CheckInterval != 0 {
 		interval = c.CheckInterval
 	}
 	if c.Timeout != 0 {
 		timeout = c.Timeout
 	}
+	if len(c.IgnoreMetrics) > 0 {
+		ignoreMetrics = c.IgnoreMetrics
+	}
+	ignoreMap := make(map[string]struct{})
+	for _, m := range ignoreMetrics {
+		ignoreMap[m] = struct{}{}
+	}
 
 	return &endpoint{
 		url:            c.URL,
 		prefix:         c.Prefix,
 		checkInterval:  interval,
 		failureMetric:  c.FailureMetric,
 		timeout:        timeout,
+		ignoreMetrics:  ignoreMap,
 		graphiteServer: g,
 		fetcher:        fetcher,
 		logger:         logger,
@@ -93,7 +102,7 @@ func (e *endpoint) Gather(ctx context.Context) []metric {
 	}
 	e.logger.Log("msg", "good fetch")
 
-	metrics = metricsFromMap(m, e.prefix)
+	metrics = metricsFromMap(m, e.prefix, e.ignoreMetrics)
 	// success
 	if e.failureMetric != "" {
 		s := metric{Name: e.failureMetric, Value: 0.0}
@@ -103,15 +112,19 @@ func (e *endpoint) Gather(ctx context.Context) []metric {
 	return metrics
 }
 
-func metricsFromMap(m map[string]interface{}, prefix string) []metric {
+func metricsFromMap(m map[string]interface{}, prefix string, ignore map[string]struct{}) []metric {
 	var metrics []metric
 	for k, v := range m {
+		_, exists := ignore[k]
+		if exists {
+			continue
+		}
 		key := fmt.Sprintf("%s.%s", prefix, k)
 		switch vv := v.(type) {
 		case float64:
 			metrics = append(metrics, metric{key, vv})
 		case map[string]interface{}:
-			nmetrics := metricsFromMap(vv, key)
+			nmetrics := metricsFromMap(vv, key, ignore)
 			for _, met := range nmetrics {
 				metrics = append(metrics, met)
 			}

endpoint_test.go

@@ -17,14 +17,15 @@ func Test_metricsFromMap(t *testing.T) {
 	data := `{"foo": 10, "bar": 5}`
 	var f interface{}
 	json.Unmarshal([]byte(data), &f)
-	metrics := metricsFromMap(f.(map[string]interface{}), "")
+	ignore := make(map[string]struct{})
+	metrics := metricsFromMap(f.(map[string]interface{}), "", ignore)
 	if len(metrics) != 2 {
 		t.Error("wrong number of metrics found")
 	}
 
 	data = `{"foo": 10, "bar": 5, "baz": {"blah": 3}}`
 	json.Unmarshal([]byte(data), &f)
-	metrics = metricsFromMap(f.(map[string]interface{}), "")
+	metrics = metricsFromMap(f.(map[string]interface{}), "", ignore)
 	if len(metrics) != 3 {
 		t.Error("wrong number of metrics found")
 	}
@@ -46,7 +47,7 @@ func Test_newEndpoint(t *testing.T) {
 		Timeout:       60,
 	}
 	g := newGraphiteServer("1.2.3.4", 2003)
-	e := newEndpoint(c, 60, 60, g, httpFetcher{}, dummyLogger())
+	e := newEndpoint(c, 60, 60, []string{}, g, httpFetcher{}, dummyLogger())
 	if e.url != c.URL {
 		t.Error("lost the URL")
 	}
@@ -66,7 +67,7 @@ func Test_Submit(t *testing.T) {
 		Timeout:       60,
 	}
 	var g dummyGraphite
-	e := newEndpoint(c, 60, 60, g, httpFetcher{}, dummyLogger())
+	e := newEndpoint(c, 60, 60, []string{}, g, httpFetcher{}, dummyLogger())
 	var m []metric
 	err := e.Submit(m)
 	if err != nil {
@@ -116,15 +117,16 @@ func Test_Fetch(t *testing.T) {
 		Timeout:       60,
 	}
 	g := newGraphiteServer("1.2.3.4", 2003)
-	e := newEndpoint(c, 60, 60, g, dummyFetcher{}, dummyLogger())
+	e := newEndpoint(c, 60, 60, []string{}, g, dummyFetcher{}, dummyLogger())
 
 	ctx := context.TODO()
 
 	d, err := e.Fetch(ctx)
 	if err != nil {
 		t.Error("dummy fetcher shouldn't fail")
 	}
-	metrics := metricsFromMap(d, "")
+	ignore := make(map[string]struct{})
+	metrics := metricsFromMap(d, "", ignore)
 	if len(metrics) != 2 {
 		t.Error("wrong number of metrics found")
 	}
@@ -139,7 +141,7 @@ func Test_Gather(t *testing.T) {
 		Timeout:       60,
 	}
 	g := newGraphiteServer("1.2.3.4", 2003)
-	e := newEndpoint(c, 60, 60, g, dummyFetcher{}, dummyLogger())
+	e := newEndpoint(c, 60, 60, []string{}, g, dummyFetcher{}, dummyLogger())
 
 	ctx := context.TODO()
 	metrics := e.Gather(ctx)
@@ -150,6 +152,26 @@ func Test_Gather(t *testing.T) {
 
 }
 
+func Test_GatherIgnoreMetric(t *testing.T) {
+	c := endpointconfig{
+		URL:           "http://example.com/",
+		Prefix:        "test",
+		CheckInterval: 60,
+		Timeout:       60,
+		IgnoreMetrics: []string{"foo"},
+	}
+	g := newGraphiteServer("1.2.3.4", 2003)
+	e := newEndpoint(c, 60, 60, []string{}, g, dummyFetcher{}, dummyLogger())
+
+	ctx := context.TODO()
+	metrics := e.Gather(ctx)
+
+	if len(metrics) != 1 {
+		t.Error("wrong number of metrics found")
+	}
+
+}
+
 func Test_GatherWithFailureMetric(t *testing.T) {
 	c := endpointconfig{
 		URL:           "http://example.com/",
@@ -159,7 +181,7 @@ func Test_GatherWithFailureMetric(t *testing.T) {
 		FailureMetric: "failure",
 	}
 	g := newGraphiteServer("1.2.3.4", 2003)
-	e := newEndpoint(c, 60, 60, g, dummyFetcher{}, dummyLogger())
+	e := newEndpoint(c, 60, 60, []string{}, g, dummyFetcher{}, dummyLogger())
 
 	ctx := context.TODO()
 	metrics := e.Gather(ctx)
@@ -178,7 +200,7 @@ func Test_Run(t *testing.T) {
 		Timeout:       60,
 	}
 	var g dummyGraphite
-	e := newEndpoint(c, 60, 60, g, dummyFetcher{}, dummyLogger())
+	e := newEndpoint(c, 60, 60, []string{}, g, dummyFetcher{}, dummyLogger())
 
 	ctx, cancel := context.WithCancel(context.TODO())
 
@@ -194,7 +216,7 @@ func Test_Run(t *testing.T) {
 		Timeout:       60,
 	}
 
-	e = newEndpoint(c, 60, 60, g, dummyFetcher{}, dummyLogger())
+	e = newEndpoint(c, 60, 60, []string{}, g, dummyFetcher{}, dummyLogger())
 
 	ctx, cancel = context.WithCancel(context.TODO())
 

samlare.go

@@ -17,13 +17,15 @@ type endpointconfig struct {
 	CheckInterval int
 	Timeout       int
 	FailureMetric string
+	IgnoreMetrics []string
 }
 
 type config struct {
 	CarbonHost    string
 	CarbonPort    int
 	CheckInterval int
 	Timeout       int
+	IgnoreMetrics []string
 
 	Endpoints map[string]endpointconfig
 }
@@ -88,7 +90,7 @@ func startEndpoints(conf *config, logger log.Logger) context.CancelFunc {
 
 	for k, endpoint := range conf.Endpoints {
 		elogger := log.With(logger, "endpoint", k)
-		e := newEndpoint(endpoint, conf.CheckInterval, conf.Timeout, g, httpFetcher{}, elogger)
+		e := newEndpoint(endpoint, conf.CheckInterval, conf.Timeout, conf.IgnoreMetrics, g, httpFetcher{}, elogger)
 		go e.Run(ctx)
 	}
 

sample-config.toml

@@ -2,6 +2,7 @@ CarbonHost = "graphite.example.com"
 CarbonPort = 2003
 CheckInterval = 60000
 Timeout = 3000
+IgnoreMetrics = ["cmdline", "foo"]
 
 [endpoints]