feat: add multiple target specification with the -t flag

README.md

@@ -35,14 +35,15 @@ pagespeed_exporter -api-key {KEY} -targets https://google.com,https://prometheus
 | Flag      | Variable           | Description                                 | Default | Required |
 |-----------|--------------------|---------------------------------------------|---------|----------|
 | -api-key  | PAGESPEED_API_KEY  | sets the google API key used for pagespeed  |         | True     |
-| -targets  | PAGESPEED_TARGETS  | comma separated list of targets to measure  |         | True     |
+| -targets  | PAGESPEED_TARGETS  | comma separated list of targets to measure  |         | False    |
+| -t        | NONE               | multi-value target array (check docker comp)|         | False    |
 | -listener | PAGESPEED_LISTENER | sets the listener address for the exporters | :9271   | False    |
 
 Note: google api key is required only if scraping more than 2 targets/second
 ### Docker
 
 ```sh
-docker run -p "9271:9271" --rm foomo/pagespeed_exporter -api-key {KEY} -targets https://google.com,https://prometheus.io
+docker run -p "9271:9271" --rm foomo/pagespeed_exporter -api-key {KEY} -t https://google.com,https://prometheus.io
 ```
 or
 ```sh

example/docker-compose.yml

@@ -5,7 +5,8 @@ services:
     image: foomo/pagespeed_exporter:latest
     restart: unless-stopped
     command:
-    - "-targets=https://www.google.com"
+    - "-t=https://www.google.com"
+    - "-t=https://www.google.com/webhp"
     # - "-api-key=${MY_API_KEY}"
 
   prometheus:

pagespeed_exporter.go

@@ -15,17 +15,28 @@ import (
 var (
 	googleApiKey    string
 	listenerAddress string
-	targets         []string
+	targets         arrayFlags
 )
 
 var (
 	Version string
 )
 
+type arrayFlags []string
+
+func (i *arrayFlags) String() string {
+	return "my string representation"
+}
+
+func (i *arrayFlags) Set(value string) error {
+	*i = append(*i, value)
+	return nil
+}
+
 func main() {
 	parseFlags()
 
-	log.Infof("starting pagespeed exporter version %s on address %s", Version, listenerAddress)
+	log.Infof("starting pagespeed exporter version %s on address %s for %d targets", Version, listenerAddress, len(targets))
 
 	psc, errCollector := collector.NewCollector(targets, googleApiKey)
 	if errCollector != nil {
@@ -40,10 +51,12 @@ func parseFlags() {
 	flag.StringVar(&googleApiKey, "api-key", getenv("PAGESPEED_API_KEY", ""), "sets the google API key used for pagespeed")
 	flag.StringVar(&listenerAddress, "listener", getenv("PAGESPEED_LISTENER", ":9271"), "sets the listener address for the exporters")
 	targetsFlag := flag.String("targets", getenv("PAGESPEED_TARGETS", ""), "comma separated list of targets to measure")
+	flag.Var(&targets, "t", "Targets on a per-line basis")
 
 	flag.Parse()
 
-	targets = strings.Split(*targetsFlag, ",")
+	additionalTargets := strings.Split(*targetsFlag, ",")
+	targets = append(targets, additionalTargets...)
 
 	if len(targets) == 0 || targets[0] == "" {
 		log.Fatal("at least one target must be specified for metrics")