add prom host (#4661)

go.mod

@@ -43,7 +43,7 @@ require (
 	k8s.io/client-go v11.0.1-0.20190805182717-6502b5e7b1b5+incompatible
 	k8s.io/utils v0.0.0-20200603063816-c1c6865ac451
 	knative.dev/hack v0.0.0-20201103151104-3d5abc3a0075
-	knative.dev/pkg v0.0.0-20201103163404-5514ab0c1fdf
+	knative.dev/pkg v0.0.0-20201215150143-89a9cc3e03a5
 	sigs.k8s.io/yaml v1.2.0
 )
 

go.sum

@@ -1101,8 +1101,8 @@ k8s.io/utils v0.0.0-20200603063816-c1c6865ac451 h1:v8ud2Up6QK1lNOKFgiIVrZdMg7Mpm
 k8s.io/utils v0.0.0-20200603063816-c1c6865ac451/go.mod h1:jPW/WVKK9YHAvNhRxK0md/EJ228hCsBRufyofKtW8HA=
 knative.dev/hack v0.0.0-20201103151104-3d5abc3a0075 h1:YAgWplKIy4O5e3F5vUUECmXAAyZ0M5ymo6fCt1jeZhs=
 knative.dev/hack v0.0.0-20201103151104-3d5abc3a0075/go.mod h1:PHt8x8yX5Z9pPquBEfIj0X66f8iWkWfR0S/sarACJrI=
-knative.dev/pkg v0.0.0-20201103163404-5514ab0c1fdf h1:QwULgRwcv6R3Ya1GZlf/E1atcaGUNw4DKjxSQUfcR6U=
-knative.dev/pkg v0.0.0-20201103163404-5514ab0c1fdf/go.mod h1:cuKOgUvJvnWHIps/apCXX8wZuMlT0dyMZLqRQfsENbQ=
+knative.dev/pkg v0.0.0-20201215150143-89a9cc3e03a5 h1:VRRec+QKr9MuDktQGHD1UDFNpDNIXYu0NuhoGeQsHiE=
+knative.dev/pkg v0.0.0-20201215150143-89a9cc3e03a5/go.mod h1:cuKOgUvJvnWHIps/apCXX8wZuMlT0dyMZLqRQfsENbQ=
 pgregory.net/rapid v0.3.3/go.mod h1:UYpPVyjFHzYBGHIxLFoupi8vwk6rXNzRY9OMvVxFIOU=
 rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=
 rsc.io/quote/v3 v3.1.0/go.mod h1:yEA65RcK8LyAZtP9Kv3t0HmxON59tX3rD+tICJqUlj0=

vendor/knative.dev/pkg/metrics/config.go

@@ -60,7 +60,9 @@ const (
 	defaultPrometheusPort = 9090
 	maxPrometheusPort     = 65535
 	minPrometheusPort     = 1024
+	defaultPrometheusHost = "0.0.0.0"
 	prometheusPortEnvName = "METRICS_PROMETHEUS_PORT"
+	prometheusHostEnvName = "METRICS_PROMETHEUS_HOST"
 )
 
 // Metrics backend "enum".
@@ -105,6 +107,10 @@ type metricsConfig struct {
 	// format. It defaults to 9090.
 	prometheusPort int
 
+	// prometheusHost is the host where the metrics are exposed in Prometheus
+	// format. It defaults to "0.0.0.0"
+	prometheusHost string
+
 	// ---- Stackdriver specific below ----
 	// True if backendDestination equals to "stackdriver". Store this in a variable
 	// to reduce string comparison operations.
@@ -240,6 +246,7 @@ func createMetricsConfig(ctx context.Context, ops ExporterOptions) (*metricsConf
 		}
 
 		mc.prometheusPort = pp
+		mc.prometheusHost = prometheusHost()
 	case stackdriver:
 		// If stackdriverClientConfig is not provided for stackdriver backend destination, OpenCensus will try to
 		// use the application default credentials. If that is not available, Opencensus would fail to create the
@@ -341,6 +348,17 @@ func prometheusPort() (int, error) {
 	return int(pp), nil
 }
 
+// prometheusHost returns the host configured via the environment
+// for the Prometheus metrics exporter if it's set, a default value otherwise.
+// No validation is done here.
+func prometheusHost() string {
+	phStr := os.Getenv(prometheusHostEnvName)
+	if phStr == "" {
+		return defaultPrometheusHost
+	}
+	return phStr
+}
+
 // JSONToOptions converts a json string to ExporterOptions.
 func JSONToOptions(jsonOpts string) (*ExporterOptions, error) {
 	var opts ExporterOptions

vendor/knative.dev/pkg/metrics/exporter.go

@@ -66,10 +66,15 @@ type ExporterOptions struct {
 
 	// PrometheusPort is the port to expose metrics if metrics backend is Prometheus.
 	// It should be between maxPrometheusPort and maxPrometheusPort. 0 value means
-	// using the default 9090 value. If is ignored if metrics backend is not
+	// using the default 9090 value. It is ignored if metrics backend is not
 	// Prometheus.
 	PrometheusPort int
 
+	// PrometheusHost is the host to expose metrics on if metrics backend is Prometheus.
+	// The default value is "0.0.0.0". It is ignored if metrics backend is not
+	// Prometheus.
+	PrometheusHost string
+
 	// ConfigMap is the data from config map config-observability. Must be present.
 	// See https://github.com/knative/serving/blob/master/config/config-observability.yaml
 	// for details.

vendor/knative.dev/pkg/metrics/prometheus_exporter.go

@@ -17,8 +17,8 @@ limitations under the License.
 package metrics
 
 import (
-	"fmt"
 	"net/http"
+	"strconv"
 	"sync"
 
 	prom "contrib.go.opencensus.io/exporter/prometheus"
@@ -50,7 +50,7 @@ func newPrometheusExporter(config *metricsConfig, logger *zap.SugaredLogger) (vi
 	logger.Infof("Created Opencensus Prometheus exporter with config: %v. Start the server for Prometheus exporter.", config)
 	// Start the server for Prometheus scraping
 	go func() {
-		srv := startNewPromSrv(e, config.prometheusPort)
+		srv := startNewPromSrv(e, config.prometheusHost, config.prometheusPort)
 		srv.ListenAndServe()
 	}()
 	return e,
@@ -73,7 +73,7 @@ func resetCurPromSrv() {
 	}
 }
 
-func startNewPromSrv(e *prom.Exporter, port int) *http.Server {
+func startNewPromSrv(e *prom.Exporter, host string, port int) *http.Server {
 	sm := http.NewServeMux()
 	sm.Handle("/metrics", e)
 	curPromSrvMux.Lock()
@@ -82,7 +82,7 @@ func startNewPromSrv(e *prom.Exporter, port int) *http.Server {
 		curPromSrv.Close()
 	}
 	curPromSrv = &http.Server{
-		Addr:    fmt.Sprint(":", port),
+		Addr:    host + ":" + strconv.Itoa(port),
 		Handler: sm,
 	}
 	return curPromSrv

vendor/modules.txt

@@ -963,7 +963,7 @@ k8s.io/utils/trace
 # knative.dev/hack v0.0.0-20201103151104-3d5abc3a0075
 ## explicit
 knative.dev/hack
-# knative.dev/pkg v0.0.0-20201103163404-5514ab0c1fdf
+# knative.dev/pkg v0.0.0-20201215150143-89a9cc3e03a5
 ## explicit
 knative.dev/pkg/apiextensions/storageversion
 knative.dev/pkg/apiextensions/storageversion/cmd/migrate