Merged the SysInfo Prometheus exporter into the existing Prometheus service

changelog/unreleased/sysinfo-prometheus.md

@@ -0,0 +1,5 @@
+Enhancement: System information included in Prometheus metrics
+
+System information is now included in the main Prometheus metrics exposed at `/metrics`. 
+
+https://github.com/cs3org/reva/pull/1071

go.sum

@@ -586,13 +586,15 @@ github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:
 github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4 h1:gQz4mCbXsO+nc9n1hCxHcGA3Zx3Eo+UHZoInFGUIXNM=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
+github.com/prometheus/client_model v0.2.0 h1:uq5h0d+GuxiXLJLNABMgp2qUWDPiLvgCzz2dUR+/W/M=
 github.com/prometheus/client_model v0.2.0/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/prometheus/common v0.0.0-20181113130724-41aa239b4cce/go.mod h1:daVV7qP5qjZbuso7PdcryaAu0sAZbrN9i7WWcTMWvro=
 github.com/prometheus/common v0.4.0/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y86RQel1bk4=
 github.com/prometheus/common v0.4.1 h1:K0MGApIoQvMw27RTdJkPbr3JZ7DNbtxQNyi5STVM6Kw=
 github.com/prometheus/common v0.4.1/go.mod h1:TNfzLD0ON7rHzMJeJkieUDPYmFC7Snx/y86RQel1bk4=
 github.com/prometheus/common v0.7.0 h1:L+1lyG48J1zAQXA3RBX/nG/B3gjlHq0zTt2tlbJLyCY=
 github.com/prometheus/common v0.7.0/go.mod h1:DjGbpBbp5NYNiECxcL/VnbXCCaQpKd3tt26CguLLsqA=
+github.com/prometheus/common v0.10.0 h1:RyRA7RzGXQZiW+tGMr7sxa85G1z0yOpM1qq5c8lNawc=
 github.com/prometheus/common v0.10.0/go.mod h1:Tlit/dnDKsSWFlCLTWaA1cyBgKHSMdTB80sz/V91rCo=
 github.com/prometheus/procfs v0.0.0-20181005140218-185b4288413d/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/procfs v0.0.0-20190507164030-5867b95ac084/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsTZCD3I8kEA=
@@ -601,6 +603,7 @@ github.com/prometheus/procfs v0.0.2/go.mod h1:TjEm7ze935MbeOT/UhFTIMYKhuLP4wbCsT
 github.com/prometheus/procfs v0.0.5/go.mod h1:4A/X28fw3Fc593LaREMrKMqOKvUAntwMDaekg4FpcdQ=
 github.com/prometheus/procfs v0.0.6 h1:0qbH+Yqu/cj1ViVLvEWCP6qMQ4efWUj6bQqOEA0V0U4=
 github.com/prometheus/procfs v0.0.6/go.mod h1:7Qr8sr6344vo1JqZ6HhLceV9o3AJ1Ff+GxbHq6oeK9A=
+github.com/prometheus/procfs v0.1.3 h1:F0+tqvhOksq22sc6iCHF5WGlWjdwj92p0udFh1VFBS8=
 github.com/prometheus/procfs v0.1.3/go.mod h1:lV6e/gmhEcM9IjHGsFOCxxuZ+z1YqCvr4OA4YeYWdaU=
 github.com/prometheus/statsd_exporter v0.15.0 h1:UiwC1L5HkxEPeapXdm2Ye0u1vUJfTj7uwT5yydYpa1E=
 github.com/prometheus/statsd_exporter v0.15.0/go.mod h1:Dv8HnkoLQkeEjkIE4/2ndAA7WL1zHKK7WMqFQqu72rw=
@@ -880,6 +883,7 @@ golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd h1:xhmwyvizuTgC2qz7ZlMluP20u
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200331124033-c3d80250170d h1:nc5K6ox/4lTFbMVSL9WRR81ixkcwXThoiF6yf+R9scA=
 golang.org/x/sys v0.0.0-20200331124033-c3d80250170d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1 h1:ogLJMz+qpzav7lGMh10LMvAkM/fAoGlaiiHYiFYdm80=
 golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
@@ -1041,6 +1045,7 @@ gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.2.5 h1:ymVxjfMaHvXD8RqPRmzHHsB3VvucivSkIAvJFDI5O3c=
 gopkg.in/yaml.v2 v2.2.5/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.0-20200605160147-a5ece683394c h1:grhR+C34yXImVGp7EzNk+DTIk+323eIUWOmEevy6bDo=

internal/http/services/prometheus/prometheus.go

@@ -22,12 +22,15 @@ import (
 	"net/http"
 
 	"contrib.go.opencensus.io/exporter/prometheus"
-	"github.com/cs3org/reva/pkg/rhttp/global"
 	"github.com/mitchellh/mapstructure"
 	"github.com/pkg/errors"
+	promclient "github.com/prometheus/client_golang/prometheus"
 	"github.com/rs/zerolog"
 	"go.opencensus.io/stats/view"
 
+	"github.com/cs3org/reva/pkg/rhttp/global"
+	"github.com/cs3org/reva/pkg/sysinfo"
+
 	// Initializes goroutines which periodically update stats
 	_ "github.com/cs3org/reva/pkg/metrics/reader/dummy"
 )
@@ -45,15 +48,23 @@ func New(m map[string]interface{}, log *zerolog.Logger) (global.Service, error)
 
 	conf.init()
 
+	registry := promclient.NewRegistry() // A Prometheus registry shared by OpenCensus and SysInfo
 	pe, err := prometheus.NewExporter(prometheus.Options{
 		Namespace: "revad",
+		Registry:  registry,
 	})
 	if err != nil {
 		return nil, errors.Wrap(err, "prometheus: error creating exporter")
 	}
 
+	// Initialize the SysInfo Prometheus exporter
+	sysinfo, err := sysinfo.NewPrometheusExporter(registry)
+	if err != nil {
+		return nil, errors.Wrap(err, "prometheus: unable to create system info exporter")
+	}
+
 	view.RegisterExporter(pe)
-	return &svc{prefix: conf.Prefix, h: pe}, nil
+	return &svc{prefix: conf.Prefix, h: pe, sysinfo: sysinfo}, nil
 }
 
 type config struct {
@@ -69,6 +80,8 @@ func (c *config) init() {
 type svc struct {
 	prefix string
 	h      http.Handler
+
+	sysinfo *sysinfo.PrometheusExporter
 }
 
 func (s *svc) Prefix() string {

internal/http/services/sysinfo/sysinfo.go

@@ -20,7 +20,6 @@ package sysinfo
 
 import (
 	"net/http"
-	"strings"
 
 	"github.com/mitchellh/mapstructure"
 	"github.com/pkg/errors"
@@ -41,8 +40,6 @@ type config struct {
 
 type svc struct {
 	conf *config
-
-	promHandler *prometheusSysInfoHandler
 }
 
 const (
@@ -67,24 +64,9 @@ func (s *svc) Unprotected() []string {
 // Handler serves all HTTP requests.
 func (s *svc) Handler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		fmt := strings.ToLower(r.URL.Query().Get("format"))
-		if len(fmt) == 0 {
-			// No format was specified, so let Prometheus handle the request
-			s.promHandler.httpHandler.ServeHTTP(w, r)
-		} else {
-			// Otherwise, provide the system information in the requested format
-			data := ""
-			switch fmt {
-			case "json":
-				data = s.getJSONData()
-			default:
-				data = "Unsupported format"
-			}
-
-			log := appctx.GetLogger(r.Context())
-			if _, err := w.Write([]byte(data)); err != nil {
-				log.Err(err).Msg("error writing SysInfo response")
-			}
+		log := appctx.GetLogger(r.Context())
+		if _, err := w.Write([]byte(s.getJSONData())); err != nil {
+			log.Err(err).Msg("error writing SysInfo response")
 		}
 	})
 }
@@ -120,16 +102,9 @@ func New(m map[string]interface{}, log *zerolog.Logger) (global.Service, error)
 		return nil, err
 	}
 
-	// Create the Prometheus system information handler
-	promHandler := &prometheusSysInfoHandler{}
-	if err := promHandler.init(); err != nil {
-		return nil, err
-	}
-
 	// Create the service
 	s := &svc{
-		conf:        conf,
-		promHandler: promHandler,
+		conf: conf,
 	}
 	return s, nil
 }

internal/http/services/sysinfo/prometheus.go → pkg/sysinfo/prometheus.go

@@ -20,46 +20,41 @@ package sysinfo
 
 import (
 	"fmt"
-	"net/http"
 	"reflect"
 	"strings"
 
 	"github.com/prometheus/client_golang/prometheus"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
 
-	"github.com/cs3org/reva/pkg/sysinfo"
 	"github.com/cs3org/reva/pkg/utils"
 )
 
-type prometheusSysInfoHandler struct {
+// PrometheusExporter exports system information via Prometheus.
+type PrometheusExporter struct {
 	registry      *prometheus.Registry
 	sysInfoMetric prometheus.GaugeFunc
-
-	httpHandler http.Handler
 }
 
-func (psysinfo *prometheusSysInfoHandler) init() error {
+func (psysinfo *PrometheusExporter) init(registry *prometheus.Registry) error {
 	// Create all necessary Prometheus objects
-	psysinfo.registry = prometheus.NewRegistry()
+	psysinfo.registry = registry
 	psysinfo.sysInfoMetric = prometheus.NewGaugeFunc(
 		prometheus.GaugeOpts{
 			Namespace:   "revad",
 			Name:        "sys_info",
 			Help:        "A metric with a constant '1' value labeled by various system information elements",
-			ConstLabels: psysinfo.getLabels("", sysinfo.SysInfo),
+			ConstLabels: psysinfo.getLabels("", SysInfo),
 		},
 		func() float64 { return 1 },
 	)
-	psysinfo.httpHandler = promhttp.HandlerFor(psysinfo.registry, promhttp.HandlerOpts{})
 
 	if err := psysinfo.registry.Register(psysinfo.sysInfoMetric); err != nil {
-		return fmt.Errorf("unable to register the system information metric: %v", err)
+		return fmt.Errorf("unable to register the system information metrics: %v", err)
 	}
 
 	return nil
 }
 
-func (psysinfo *prometheusSysInfoHandler) getLabels(root string, i interface{}) prometheus.Labels {
+func (psysinfo *PrometheusExporter) getLabels(root string, i interface{}) prometheus.Labels {
 	labels := prometheus.Labels{}
 
 	// Iterate over each field of the given interface, recursively collecting the values as labels
@@ -92,3 +87,17 @@ func (psysinfo *prometheusSysInfoHandler) getLabels(root string, i interface{})
 
 	return labels
 }
+
+// NewPrometheusExporter creates a new Prometheus system information exporter.
+func NewPrometheusExporter(registry *prometheus.Registry) (*PrometheusExporter, error) {
+	if registry == nil {
+		return nil, fmt.Errorf("no registry provided")
+	}
+
+	exporter := &PrometheusExporter{}
+	if err := exporter.init(registry); err != nil {
+		return nil, err
+	}
+
+	return exporter, nil
+}