PMM-1901 Metrics endpoint and collectors filtering.

.golangci.yml

@@ -13,6 +13,9 @@ linters-settings:
 
 linters:
   enable-all: true
+  disable:
+    - scopelint         # too many false positives
+    - gochecknoglobals  # mostly useless
 
 issues:
   exclude-use-default: false

README.md

@@ -52,20 +52,46 @@ scrape_configs:
   - job_name: rds-basic
     scrape_interval: 60s
     scrape_timeout: 55s
-    metrics_path: /basic
     honor_labels: true
     static_configs:
       - targets:
         - 127.0.0.1:9042
+    params:
+        collect[]:
+          - basic
 
   - job_name: rds-enhanced
     scrape_interval: 10s
     scrape_timeout: 9s
-    metrics_path: /enhanced
     honor_labels: true
     static_configs:
       - targets:
         - 127.0.0.1:9042
+    params:
+        collect[]:
+          - enhanced
 ```
 
 `honor_labels: true` is important because exporter returns metrics with `instance` label set.
+
+## Collectors
+
+### Enabled by default
+
+Name     | Description 
+---------|-------------
+basic | Basic metrics from https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/MonitoringOverview.html#monitoring-cloudwatch.
+enhanced | Enhanced metrics from https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_Monitoring.OS.html.
+
+### Filtering enabled collectors
+
+The `rds_exporter` will expose all metrics from enabled collectors by default.
+
+For advanced use the `rds_exporter` can be passed an optional list of collectors to filter metrics. The `collect[]` parameter may be used multiple times.  In Prometheus configuration you can use this syntax under the [scrape config](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#<scrape_config>).
+
+```
+  params:
+    collect[]:
+      - basic
+      - enhanced
+```

basic/basic.go

@@ -11,8 +11,6 @@ import (
 	"github.com/percona/rds_exporter/sessions"
 )
 
-//go:generate go run generate/main.go generate/utils.go
-
 var (
 	scrapeTimeDesc = prometheus.NewDesc(
 		"rds_exporter_scrape_duration_seconds",
@@ -22,6 +20,16 @@ var (
 	)
 )
 
+// OverlappingMetrics flag.
+type OverlappingMetrics bool
+
+const (
+	// EnableOverlapping flag for enabling overlapping metrics.
+	EnableOverlapping OverlappingMetrics = true
+	// DisableOverlapping flag for disabling overlapping metrics.
+	DisableOverlapping OverlappingMetrics = false
+)
+
 type Metric struct {
 	Name string
 	Desc *prometheus.Desc
@@ -35,11 +43,19 @@ type Exporter struct {
 }
 
 // New creates a new instance of a Exporter.
-func New(config *config.Config, sessions *sessions.Sessions) *Exporter {
+// enableOverlapping is using for backward compatibility.
+// See: https://jira.percona.com/browse/PMM-1901.
+func New(config *config.Config, sessions *sessions.Sessions, enableOverlapping OverlappingMetrics) *Exporter {
+	var m []Metric
+	m = append(m, Metrics...)
+	if enableOverlapping {
+		m = append(m, MetricsOverlappingWithEnhancedCollector...)
+	}
+
 	return &Exporter{
 		config:   config,
 		sessions: sessions,
-		metrics:  Metrics,
+		metrics:  m,
 		l:        log.With("component", "basic"),
 	}
 }

basic/basic_test.go

@@ -13,19 +13,36 @@ import (
 	"github.com/percona/rds_exporter/sessions"
 )
 
-func getExporter(t *testing.T) *Exporter {
+func getExporter(t *testing.T, enableMetrics OverlappingMetrics) *Exporter {
 	t.Helper()
 
 	cfg, err := config.Load("../config.yml")
 	require.NoError(t, err)
 	client := client.New()
 	sess, err := sessions.New(cfg.Instances, client.HTTP(), false)
 	require.NoError(t, err)
-	return New(cfg, sess)
+	return New(cfg, sess, enableMetrics)
 }
 
 func TestCollector_Describe(t *testing.T) {
-	c := getExporter(t)
+	c := getExporter(t, DisableOverlapping)
+	ch := make(chan *prometheus.Desc)
+	go func() {
+		c.Describe(ch)
+		close(ch)
+	}()
+
+	const expected = 47
+	descs := make([]*prometheus.Desc, 0, expected)
+	for d := range ch {
+		descs = append(descs, d)
+	}
+
+	assert.Equal(t, expected, len(descs), "%+v", descs)
+}
+
+func TestCollector_Describe_WithOverlappingMetrics(t *testing.T) {
+	c := getExporter(t, EnableOverlapping)
 	ch := make(chan *prometheus.Desc)
 	go func() {
 		c.Describe(ch)
@@ -42,7 +59,24 @@ func TestCollector_Describe(t *testing.T) {
 }
 
 func TestCollector_Collect(t *testing.T) {
-	c := getExporter(t)
+	c := getExporter(t, DisableOverlapping)
+	ch := make(chan prometheus.Metric)
+	go func() {
+		c.Collect(ch)
+		close(ch)
+	}()
+
+	const expected = 91
+	metrics := make([]helpers.Metric, 0, expected)
+	for m := range ch {
+		metrics = append(metrics, *helpers.ReadMetric(m))
+	}
+
+	assert.Equal(t, expected, len(metrics), "%+v", metrics)
+}
+
+func TestCollector_Collect_WithOverlappingMetrics(t *testing.T) {
+	c := getExporter(t, EnableOverlapping)
 	ch := make(chan prometheus.Metric)
 	go func() {
 		c.Collect(ch)