PMM-4474 Add extra labels. (#32)

Author: AlekSi

Gopkg.lock

@@ -26,13 +26,17 @@ instances:
     region: us-east-1
     aws_access_key: AKIAIOSFODNN7EXAMPLE
     aws_secret_key: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
+    labels:
+      foo: bar
+      baz: qux
 ```
 
 If `aws_access_key` and `aws_secret_key` are present, they are used for that instance.
 Otherwise, [default credential provider chain](https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/configuring-sdk.html#specifying-credentials)
 is used, which includes `AWS_ACCESS_KEY_ID`/`AWS_ACCESS_KEY` and `AWS_SECRET_ACCESS_KEY`/`AWS_SECRET_KEY` environment variables, `~/.aws/credentials` file,
 and IAM role for EC2.
 
+Returned metrics contain `instance` and `region` labels set. They also contain extra labels specified in the configuration file.
 
 Start exporter by running:
 ```

README.md

@@ -23,42 +23,46 @@ var (
 )
 
 type Metric struct {
-	Name string
-	Desc *prometheus.Desc
+	cwName         string
+	prometheusName string
+	prometheusHelp string
 }
 
-type Exporter struct {
+type Collector struct {
 	config   *config.Config
 	sessions *sessions.Sessions
 	metrics  []Metric
 	l        log.Logger
 }
 
-// New creates a new instance of a Exporter.
-func New(config *config.Config, sessions *sessions.Sessions) *Exporter {
-	return &Exporter{
+// New creates a new instance of a Collector.
+func New(config *config.Config, sessions *sessions.Sessions) *Collector {
+	return &Collector{
 		config:   config,
 		sessions: sessions,
 		metrics:  Metrics,
 		l:        log.With("component", "basic"),
 	}
 }
 
-func (e *Exporter) Collect(ch chan<- prometheus.Metric) {
+func (e *Collector) Describe(ch chan<- *prometheus.Desc) {
+	// unchecked collector
+}
+
+func (e *Collector) Collect(ch chan<- prometheus.Metric) {
 	now := time.Now()
 	e.collect(ch)
 
 	// Collect scrape time
 	ch <- prometheus.MustNewConstMetric(scrapeTimeDesc, prometheus.GaugeValue, time.Since(now).Seconds())
 }
 
-func (e *Exporter) collect(ch chan<- prometheus.Metric) {
-	wg := &sync.WaitGroup{}
+func (e *Collector) collect(ch chan<- prometheus.Metric) {
+	var wg sync.WaitGroup
 	defer wg.Wait()
 
-	instances := e.config.Instances
-	wg.Add(len(instances))
-	for _, instance := range instances {
+	wg.Add(len(e.config.Instances))
+	for _, instance := range e.config.Instances {
 		instance := instance
 		go func() {
 			defer wg.Done()
@@ -73,12 +77,7 @@ func (e *Exporter) collect(ch chan<- prometheus.Metric) {
 	}
 }
 
-func (e *Exporter) Describe(ch chan<- *prometheus.Desc) {
-	// RDS metrics
-	for _, m := range e.metrics {
-		ch <- m.Desc
-	}
-
-	// Scrape time
-	ch <- scrapeTimeDesc
-}
+// check interfaces
+var (
+	_ prometheus.Collector = (*Collector)(nil)
+)

basic/basic.go renamed to basic/collector.go

@@ -13,7 +13,7 @@ import (
 	"github.com/percona/rds_exporter/sessions"
 )
 
-func getExporter(t *testing.T) *Exporter {
+func getCollector(t *testing.T) *Collector {
 	t.Helper()
 
 	cfg, err := config.Load("../config.yml")
@@ -25,7 +25,7 @@ func getExporter(t *testing.T) *Exporter {
 }
 
 func TestCollector_Describe(t *testing.T) {
-	c := getExporter(t)
+	c := getCollector(t)
 	ch := make(chan *prometheus.Desc)
 	go func() {
 		c.Describe(ch)
@@ -42,7 +42,7 @@ func TestCollector_Describe(t *testing.T) {
 }
 
 func TestCollector_Collect(t *testing.T) {
-	c := getExporter(t)
+	c := getCollector(t)
 	ch := make(chan prometheus.Metric)
 	go func() {
 		c.Collect(ch)