Caiwc/multi target (#234)

caiwc · wccai · wccai · web-flow · commit da042f8abe5f · 2023-02-11T16:38:38.000+01:00
* feat(): support scrape multi target

rebase branch &amp;&amp; update Makefile version

* add multi-target explain to readme

* docs: correct dns example port of readme

---------

Co-authored-by: wccai &lt;wccai@easyops.cn&gt;
Co-authored-by: wccai &lt;wccai@easyops&gt;
diff --git a/Makefile b/Makefile
@@ -3,7 +3,7 @@ OS_TYPE        ?= $(shell uname -s | tr '[:upper:]' '[:lower:]')
 ARCH_TYPE      ?= $(subst x86_64,amd64,$(patsubst i%86,386,$(ARCH)))
 GOOS           ?= $(shell go env GOOS)
 GOARCH         ?= $(shell go env GOARCH)
-VERSION        ?= 0.4.2
+VERSION        ?= 0.4.3
 MAJOR_VERSION  ?= 21
 MINOR_VERSION  ?= 8
 ORACLE_VERSION ?= $(MAJOR_VERSION).$(MINOR_VERSION)
diff --git a/README.md b/README.md
@@ -533,3 +533,10 @@ using the `--web.config` parameter. The format of the file is described
 
 Note that the TLS and basic authentication settings affect all HTTP endpoints:
 /metrics for scraping, /probe for probing, and the web UI.
+
+
+## Multi-target support
+
+This exporter supports the multi-target pattern. This allows running a single instance of this exporter for multiple Oracle targets.
+
+To use the multi-target functionality, send a http request to the endpoint `/scrape?target=foo:1521` where target is set to the DSN of the Oracle instance to scrape metrics from.
diff --git a/main.go b/main.go
@@ -610,6 +610,7 @@ func main() {
 		ErrorHandling: promhttp.ContinueOnError,
 	}
 	http.Handle(*metricPath, promhttp.HandlerFor(prometheus.DefaultGatherer, opts))
+	http.HandleFunc("/scrape", scrapeHandle(logger))
 
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Write([]byte("<html><head><title>Oracle DB Exporter " + Version + "</title></head><body><h1>Oracle DB Exporter " + Version + "</h1><p><a href='" + *metricPath + "'>Metrics</a></p></body></html>"))
@@ -621,3 +622,19 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+func scrapeHandle(logger log.Logger) func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		target := r.URL.Query().Get("target")
+		exporter := NewExporter(target, logger)
+		registry := prometheus.NewRegistry()
+		registry.MustRegister(exporter)
+		gatherers := prometheus.Gatherers{
+			prometheus.DefaultGatherer,
+			registry,
+		}
+		// Delegate http serving to Prometheus client library, which will call collector.Collect.
+		h := promhttp.HandlerFor(gatherers, promhttp.HandlerOpts{})
+		h.ServeHTTP(w, r)
+	}
+}
