From 9827e1865af3dbce16f08b546d478fc963d49cde Mon Sep 17 00:00:00 2001
From: Dmitry Vasiliev <vadv.mkn@gmail.com>
Date: Sun, 17 May 2020 16:58:41 +0300
Subject: [PATCH] update readme

---
 README.md        | 27 +++++++++++++++++++++++++++
 cmd/config.go    | 10 +++++-----
 cmd/main.go      |  2 +-
 merger/merger.go | 18 +++++++++---------
 4 files changed, 42 insertions(+), 15 deletions(-)
 create mode 100644 README.md

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..8a4d225
--- /dev/null
+++ b/README.md
@@ -0,0 +1,27 @@
+# prometheus-exporter-merger
+
+Merges Prometheus metrics from multiple sources.
+
+## But Why?!
+
+> [prometheus/prometheus#3756](https://github.com/prometheus/prometheus/issues/3756)
+
+To start the exporter:
+
+```
+prometheus-exporter-merger --config config.yaml
+```
+
+Config example:
+
+```yaml
+listen: :8080
+scrap_timeout: 20s
+sources:
+  - url: http://127.0.0.1:8081/metrics
+    labels:
+      key1: value1
+  - url: http://127.0.0.1:8082/metrics
+    labels:
+      key2: value2
+```
\ No newline at end of file
diff --git a/cmd/config.go b/cmd/config.go
index 24e95b5..9dfbad3 100644
--- a/cmd/config.go
+++ b/cmd/config.go
@@ -13,9 +13,9 @@ type source struct {
 }
 
 type config struct {
-	Listen  string        `yaml:"listen"`
-	Timeout time.Duration `yaml:"timeout"`
-	Sources []*source     `yaml:"sources"`
+	Listen       string        `yaml:"listen"`
+	ScrapTimeout time.Duration `yaml:"scrap_timeout"`
+	Sources      []*source     `yaml:"sources"`
 }
 
 func parseConfig(filename string) (*config, error) {
@@ -24,8 +24,8 @@ func parseConfig(filename string) (*config, error) {
 		return nil, err
 	}
 	result := &config{
-		Listen:  ":8080",
-		Timeout: 15 * time.Second,
+		Listen:       ":8080",
+		ScrapTimeout: 15 * time.Second,
 	}
 	return result, yaml.Unmarshal(data, result)
 }
diff --git a/cmd/main.go b/cmd/main.go
index 2b0b85d..59cc74e 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -24,7 +24,7 @@ func Execute() {
 		panic(err)
 	}
 
-	m := merger.New(c.Timeout)
+	m := merger.New(c.ScrapTimeout)
 	for _, s := range c.Sources {
 		var labels []*prom.LabelPair
 		for k, v := range s.Labels {
diff --git a/merger/merger.go b/merger/merger.go
index 60d0b55..c8710d5 100644
--- a/merger/merger.go
+++ b/merger/merger.go
@@ -16,10 +16,10 @@ type Merger interface {
 }
 
 type merger struct {
-	mu      sync.Mutex
-	timeout time.Duration
-	client  *http.Client
-	sources []*source
+	mu           sync.Mutex
+	scrapTimeout time.Duration
+	client       *http.Client
+	sources      []*source
 }
 
 type source struct {
@@ -27,7 +27,7 @@ type source struct {
 	labels []*prom.LabelPair
 }
 
-func New(timeout time.Duration) Merger {
+func New(scrapTimeout time.Duration) Merger {
 	client := &http.Client{
 		Transport: &http.Transport{
 			DisableKeepAlives:   false,
@@ -37,11 +37,11 @@ func New(timeout time.Duration) Merger {
 			MaxConnsPerHost:     10,
 			IdleConnTimeout:     5 * time.Minute,
 		},
-		Timeout: timeout,
+		Timeout: scrapTimeout,
 	}
 	return &merger{
-		timeout: timeout,
-		client:  client,
+		scrapTimeout: scrapTimeout,
+		client:       client,
 	}
 }
 
@@ -56,7 +56,7 @@ func (m *merger) AddSource(url string, labels []*prom.LabelPair) {
 func (m *merger) Merge(w io.Writer) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	ctx, cancel := context.WithTimeout(context.Background(), m.timeout)
+	ctx, cancel := context.WithTimeout(context.Background(), m.scrapTimeout)
 	defer cancel()
 	return m.merge(ctx, w)
 }