Add constant labels feature

README.md

@@ -37,17 +37,19 @@ Usage:
   php-fpm-exporter [flags]
 
 Flags:
-      --addr string       listen address for metrics handler (default "127.0.0.1:8080")
-      --endpoint string   url for php-fpm status (default "http://127.0.0.1:9000/status")
-      --fastcgi string    fastcgi url. If this is set, fastcgi will be used instead of HTTP
+      --addr="127.0.0.1:8080"                       listen address for metrics handler
+      --endpoint="http://127.0.0.1:9000/status"     url for php-fpm status
+      --fastcgi=FASTCGI                             fastcgi url. If this is set, fastcgi will be used instead of HTTP
+      --web.telemetry-path="/metrics"               Path under which to expose metrics. Cannot be /
+      --labels=LABELS                               A list of labels, that will be assigned to all metrics. For example "service=api,dc=us-west"
 ```
 
 When running, a simple healthcheck is available on `/healthz`
 
-To use the HTTP endpoint you must pass through `/status` in your webserver 
+To use the HTTP endpoint you must pass through `/status` in your webserver
 and configure php-fpm to handle status requests. Example for nginx: https://easyengine.io/tutorials/php/fpm-status-page/
 
-To use Fastcgi, set `--fastcgi` to a url such as `tcp://127.0.0.1:9090/status` if php-fpm is listening on a tcp socket or 
+To use Fastcgi, set `--fastcgi` to a url such as `tcp://127.0.0.1:9090/status` if php-fpm is listening on a tcp socket or
 `unix:///path/to/php.sock` for a unix socket. Note: php-fpm must be configured to use `/status` if using a unix socket, `php-fpm-exporter` does not currently support changing this.
 
 Metrics

cmd/php-fpm-exporter/main.go

@@ -13,6 +13,7 @@ func main() {
 		endpoint        = kingpin.Flag("endpoint", "url for php-fpm status").Default("http://127.0.0.1:9000/status").Envar("ENDPOINT_URL").String()
 		fcgiEndpoint    = kingpin.Flag("fastcgi", "fastcgi url. If this is set, fastcgi will be used instead of HTTP").Envar("FASTCGI_URL").String()
 		metricsEndpoint = kingpin.Flag("web.telemetry-path", "Path under which to expose metrics. Cannot be /").Default("/metrics").Envar("TELEMETRY_PATH").String()
+		labels          = kingpin.Flag("labels", "A list of constant labels, that will be assigned to all metrics. For example \"service=payments-api,dc=us-west\"").Envar("METRIC_LABELS").String()
 	)
 
 	kingpin.HelpFlag.Short('h')
@@ -29,6 +30,7 @@ func main() {
 		exporter.SetFastcgi(*fcgiEndpoint),
 		exporter.SetLogger(logger),
 		exporter.SetMetricsEndpoint(*metricsEndpoint),
+		exporter.SetLabels(*labels),
 	)
 
 	if err != nil {

collector.go

@@ -34,26 +34,26 @@ type collector struct {
 
 const metricsNamespace = "phpfpm"
 
-func newFuncMetric(metricName string, docString string, labels []string) *prometheus.Desc {
+func newFuncMetric(metricName string, docString string, labels []string, constLabels prometheus.Labels) *prometheus.Desc {
 	return prometheus.NewDesc(
 		prometheus.BuildFQName(metricsNamespace, "", metricName),
-		docString, labels, nil,
+		docString, labels, constLabels,
 	)
 }
 
 func (e *Exporter) newCollector() *collector {
 	return &collector{
 		exporter:           e,
-		up:                 newFuncMetric("up", "able to contact php-fpm", nil),
-		acceptedConn:       newFuncMetric("accepted_connections_total", "Total number of accepted connections", nil),
-		listenQueue:        newFuncMetric("listen_queue_connections", "Number of connections that have been initiated but not yet accepted", nil),
-		maxListenQueue:     newFuncMetric("listen_queue_max_connections", "Max number of connections the listen queue has reached since FPM start", nil),
-		listenQueueLength:  newFuncMetric("listen_queue_length_connections", "The length of the socket queue, dictating maximum number of pending connections", nil),
-		phpProcesses:       newFuncMetric("processes_total", "process count", []string{"state"}),
-		maxActiveProcesses: newFuncMetric("active_max_processes", "Maximum active process count", nil),
-		maxChildrenReached: newFuncMetric("max_children_reached_total", "Number of times the process limit has been reached", nil),
-		slowRequests:       newFuncMetric("slow_requests_total", "Number of requests that exceed request_slowlog_timeout", nil),
-		scrapeFailures:     newFuncMetric("scrape_failures_total", "Number of errors while scraping php_fpm", nil),
+		up:                 newFuncMetric("up", "able to contact php-fpm", nil, e.constantLabels),
+		acceptedConn:       newFuncMetric("accepted_connections_total", "Total number of accepted connections", nil, e.constantLabels),
+		listenQueue:        newFuncMetric("listen_queue_connections", "Number of connections that have been initiated but not yet accepted", nil, e.constantLabels),
+		maxListenQueue:     newFuncMetric("listen_queue_max_connections", "Max number of connections the listen queue has reached since FPM start", nil, e.constantLabels),
+		listenQueueLength:  newFuncMetric("listen_queue_length_connections", "The length of the socket queue, dictating maximum number of pending connections", nil, e.constantLabels),
+		phpProcesses:       newFuncMetric("processes_total", "process count", []string{"state"}, e.constantLabels),
+		maxActiveProcesses: newFuncMetric("active_max_processes", "Maximum active process count", nil, e.constantLabels),
+		maxChildrenReached: newFuncMetric("max_children_reached_total", "Number of times the process limit has been reached", nil, e.constantLabels),
+		slowRequests:       newFuncMetric("slow_requests_total", "Number of requests that exceed request_slowlog_timeout", nil, e.constantLabels),
+		scrapeFailures:     newFuncMetric("scrape_failures_total", "Number of errors while scraping php_fpm", nil, e.constantLabels),
 	}
 }
 

exporter.go

@@ -7,6 +7,7 @@ import (
 	"net/url"
 	"os"
 	"os/signal"
+	"strings"
 	"syscall"
 	"time"
 
@@ -24,6 +25,7 @@ type Exporter struct {
 	fcgiEndpoint    *url.URL
 	logger          *zap.Logger
 	metricsEndpoint string
+	constantLabels  prometheus.Labels
 }
 
 // OptionsFunc is a function passed to new for setting options on a new Exporter.
@@ -95,6 +97,23 @@ func SetEndpoint(rawurl string) func(*Exporter) error {
 	}
 }
 
+func SetLabels(labels string) func(*Exporter) error {
+	return func(e *Exporter) error {
+		if labels == "" {
+			return nil
+		}
+
+		labelsMap := make(map[string]string)
+		for _, label := range strings.Split(labels, ",") {
+			kv := strings.Split(label, "=")
+			labelsMap[kv[0]] = kv[1]
+		}
+
+		e.constantLabels = labelsMap
+		return nil
+	}
+}
+
 // SetFastcgi creates a function that will set the fastcgi URL endpoint to contact
 // php-fpm. If this is set, then fastcgi is used rather than HTTP.
 // Generally only used when create a new Exporter.