Added support exposing metrics in Prometheus format

agent/agent_endpoint.go

@@ -19,6 +19,8 @@ import (
 	"github.com/hashicorp/logutils"
 	"github.com/hashicorp/serf/coordinate"
 	"github.com/hashicorp/serf/serf"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 type Self struct {
@@ -86,7 +88,17 @@ func (s *HTTPServer) AgentMetrics(resp http.ResponseWriter, req *http.Request) (
 	if rule != nil && !rule.AgentRead(s.agent.config.NodeName) {
 		return nil, acl.ErrPermissionDenied
 	}
+	if format := req.URL.Query().Get("format"); format == "prometheus" {
+		handlerOptions := promhttp.HandlerOpts{
+			ErrorLog:           s.agent.logger,
+			ErrorHandling:      promhttp.ContinueOnError,
+			DisableCompression: true,
+		}
 
+		handler := promhttp.HandlerFor(prometheus.DefaultGatherer, handlerOptions)
+		handler.ServeHTTP(resp, req)
+		return nil, nil
+	}
 	return s.agent.MemSink.DisplayMetrics(resp, req)
 }
 

agent/config/builder.go

@@ -626,6 +626,7 @@ func (b *Builder) Build() (rt RuntimeConfig, err error) {
 		TelemetryDisableHostname:                    b.boolVal(c.Telemetry.DisableHostname),
 		TelemetryDogstatsdAddr:                      b.stringVal(c.Telemetry.DogstatsdAddr),
 		TelemetryDogstatsdTags:                      c.Telemetry.DogstatsdTags,
+		TelemetryPrometheusDisable:                  b.boolVal(c.Telemetry.PrometheusDisable),
 		TelemetryFilterDefault:                      b.boolVal(c.Telemetry.FilterDefault),
 		TelemetryAllowedPrefixes:                    telemetryAllowedPrefixes,
 		TelemetryBlockedPrefixes:                    telemetryBlockedPrefixes,

agent/config/config.go

@@ -394,6 +394,7 @@ type Telemetry struct {
 	FilterDefault                      *bool    `json:"filter_default,omitempty" hcl:"filter_default" mapstructure:"filter_default"`
 	PrefixFilter                       []string `json:"prefix_filter,omitempty" hcl:"prefix_filter" mapstructure:"prefix_filter"`
 	MetricsPrefix                      *string  `json:"metrics_prefix,omitempty" hcl:"metrics_prefix" mapstructure:"metrics_prefix"`
+	PrometheusDisable                  *bool    `json:"prometheus_disable,omitempty" hcl:"prometheus_disable" mapstructure:"prometheus_disable"`
 	StatsdAddr                         *string  `json:"statsd_address,omitempty" hcl:"statsd_address" mapstructure:"statsd_address"`
 	StatsiteAddr                       *string  `json:"statsite_address,omitempty" hcl:"statsite_address" mapstructure:"statsite_address"`
 	EnableDeprecatedNames              *bool    `json:"enable_deprecated_names" hcl:"enable_deprecated_names" mapstructure:"enable_deprecated_names"`

agent/config/runtime.go

@@ -425,6 +425,11 @@ type RuntimeConfig struct {
 	// hcl: telemetry { dogstatsd_tags = []string }
 	TelemetryDogstatsdTags []string
 
+	// TelemetryPrometheusDisable enables prometheus Support for metrics
+	//
+	// hcl: telemetry { prometheus_disable = (true|false) }
+	TelemetryPrometheusDisable bool
+
 	// TelemetryFilterDefault is the default for whether to allow a metric that's not
 	// covered by the filter.
 	//

agent/config/runtime_test.go

@@ -2589,6 +2589,7 @@ func TestFullConfig(t *testing.T) {
 				"prefix_filter": [ "+oJotS8XJ","-cazlEhGn" ],
 				"enable_deprecated_names": true,
 				"metrics_prefix": "ftO6DySn",
+				"prometheus_disable": true,
 				"statsd_address": "drce87cy",
 				"statsite_address": "HpFwKB8R"
 			},
@@ -3026,6 +3027,7 @@ func TestFullConfig(t *testing.T) {
 				prefix_filter = [ "+oJotS8XJ","-cazlEhGn" ]
 				enable_deprecated_names = true
 				metrics_prefix = "ftO6DySn"
+				prometheus_disable = true
 				statsd_address = "drce87cy"
 				statsite_address = "HpFwKB8R"
 			}
@@ -3588,6 +3590,7 @@ func TestFullConfig(t *testing.T) {
 		TelemetryAllowedPrefixes:                    []string{"oJotS8XJ", "consul.consul"},
 		TelemetryBlockedPrefixes:                    []string{"cazlEhGn"},
 		TelemetryMetricsPrefix:                      "ftO6DySn",
+		TelemetryPrometheusDisable:                  true,
 		TelemetryStatsdAddr:                         "drce87cy",
 		TelemetryStatsiteAddr:                       "HpFwKB8R",
 		TLSCipherSuites:                             []uint16{tls.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305, tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384},
@@ -4140,6 +4143,7 @@ func TestSanitize(t *testing.T) {
     "TelemetryDogstatsdTags": [],
     "TelemetryFilterDefault": false,
     "TelemetryMetricsPrefix": "",
+    "TelemetryPrometheusDisable": false,
     "TelemetryStatsdAddr": "",
     "TelemetryStatsiteAddr": "",
     "TranslateWANAddrs": false,

command/agent/agent.go

@@ -15,6 +15,7 @@ import (
 	"github.com/armon/go-metrics"
 	"github.com/armon/go-metrics/circonus"
 	"github.com/armon/go-metrics/datadog"
+	"github.com/armon/go-metrics/prometheus"
 	"github.com/hashicorp/consul/agent"
 	"github.com/hashicorp/consul/agent/config"
 	"github.com/hashicorp/consul/command/flags"
@@ -208,6 +209,17 @@ func dogstatdSink(config *config.RuntimeConfig, hostname string) (metrics.Metric
 	return sink, nil
 }
 
+func prometheusSink(config *config.RuntimeConfig, hostname string) (metrics.MetricSink, error) {
+	if config.TelemetryPrometheusDisable {
+		return nil, nil
+	}
+	sink, err := prometheus.NewPrometheusSink()
+	if err != nil {
+		return nil, err
+	}
+	return sink, nil
+}
+
 func circonusSink(config *config.RuntimeConfig, hostname string) (metrics.MetricSink, error) {
 	if config.TelemetryCirconusAPIToken == "" && config.TelemetryCirconusSubmissionURL == "" {
 		return nil, nil
@@ -284,6 +296,9 @@ func startupTelemetry(conf *config.RuntimeConfig) (*metrics.InmemSink, error) {
 	if err := addSink("circonus", circonusSink); err != nil {
 		return nil, err
 	}
+	if err := addSink("prometheus", prometheusSink); err != nil {
+		return nil, err
+	}
 
 	if len(sinks) > 0 {
 		sinks = append(sinks, memSink)