update promlog to latest version (#4876)

* update promlog to latest version

Signed-off-by: Alex Yu <yu.alex96@gmail.com>

* Update api tests, fix main setup

Signed-off-by: Alex Yu <yu.alex96@gmail.com>

* tidy go.sum

Signed-off-by: Alex Yu <yu.alex96@gmail.com>

* revendor prometheus/common

Signed-off-by: Alex Yu <yu.alex96@gmail.com>

* only initialize config; use kingpin for remote_storage_adapter

Signed-off-by: Alex Yu <yu.alex96@gmail.com>

* actually parse the flags

Signed-off-by: Alex Yu <yu.alex96@gmail.com>

* clean up imports

Signed-off-by: Alex Yu <yu.alex96@gmail.com>

cmd/prometheus/main.go

@@ -101,11 +101,12 @@ func main() {
 
 		prometheusURL string
 
-		logLevel promlog.AllowedLevel
+		promlogConfig promlog.Config
 	}{
 		notifier: notifier.Options{
 			Registerer: prometheus.DefaultRegisterer,
 		},
+		promlogConfig: promlog.Config{},
 	}
 
 	a := kingpin.New(filepath.Base(os.Args[0]), "The Prometheus monitoring server")
@@ -204,7 +205,7 @@ func main() {
 	a.Flag("query.max-samples", "Maximum number of samples a single query can load into memory. Note that queries will fail if they would load more samples than this into memory, so this also limits the number of samples a query can return.").
 		Default("50000000").IntVar(&cfg.queryMaxSamples)
 
-	promlogflag.AddFlags(a, &cfg.logLevel)
+	promlogflag.AddFlags(a, &cfg.promlogConfig)
 
 	_, err := a.Parse(os.Args[1:])
 	if err != nil {
@@ -233,7 +234,7 @@ func main() {
 
 	promql.LookbackDelta = time.Duration(cfg.lookbackDelta)
 
-	logger := promlog.New(cfg.logLevel)
+	logger := promlog.New(&cfg.promlogConfig)
 
 	// XXX(fabxc): Kubernetes does background logging which we can only customize by modifying
 	// a global variable.

documentation/examples/remote_storage/remote_storage_adapter/main.go

@@ -15,13 +15,13 @@
 package main
 
 import (
-	"flag"
 	"fmt"
 	"io/ioutil"
 	"net/http"
 	_ "net/http/pprof"
 	"net/url"
 	"os"
+	"path/filepath"
 	"sync"
 	"time"
 
@@ -29,13 +29,17 @@ import (
 	"github.com/go-kit/kit/log/level"
 	"github.com/gogo/protobuf/proto"
 	"github.com/golang/snappy"
+	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/model"
+	"gopkg.in/alecthomas/kingpin.v2"
 
 	influx "github.com/influxdata/influxdb/client/v2"
 
 	"github.com/prometheus/common/promlog"
+	"github.com/prometheus/common/promlog/flag"
+
 	"github.com/prometheus/prometheus/documentation/examples/remote_storage/remote_storage_adapter/graphite"
 	"github.com/prometheus/prometheus/documentation/examples/remote_storage/remote_storage_adapter/influxdb"
 	"github.com/prometheus/prometheus/documentation/examples/remote_storage/remote_storage_adapter/opentsdb"
@@ -55,7 +59,7 @@ type config struct {
 	remoteTimeout           time.Duration
 	listenAddr              string
 	telemetryPath           string
-	logLevel                string
+	promlogConfig           promlog.Config
 }
 
 var (
@@ -100,11 +104,7 @@ func main() {
 	cfg := parseFlags()
 	http.Handle(cfg.telemetryPath, promhttp.Handler())
 
-	logLevel := promlog.AllowedLevel{}
+	logger := promlog.New(&cfg.promlogConfig)
-	if err := logLevel.Set(cfg.logLevel); err != nil {
-		panic(fmt.Sprintf("Error setting log level: %v", err))
-	}
-	logger := promlog.New(logLevel)
 
 	writers, readers := buildClients(logger, cfg)
 	if err := serve(logger, cfg.listenAddr, writers, readers); err != nil {
@@ -114,42 +114,45 @@ func main() {
 }
 
 func parseFlags() *config {
+	a := kingpin.New(filepath.Base(os.Args[0]), "Remote storage adapter")
+	a.HelpFlag.Short('h')
+
 	cfg := &config{
 		influxdbPassword: os.Getenv("INFLUXDB_PW"),
+		promlogConfig:    promlog.Config{},
 	}
 
-	flag.StringVar(&cfg.graphiteAddress, "graphite-address", "",
+	a.Flag("graphite-address", "The host:port of the Graphite server to send samples to. None, if empty.").
-		"The host:port of the Graphite server to send samples to. None, if empty.",
+		Default("").StringVar(&cfg.graphiteAddress)
-	)
+	a.Flag("graphite-transport", "Transport protocol to use to communicate with Graphite. 'tcp', if empty.").
-	flag.StringVar(&cfg.graphiteTransport, "graphite-transport", "tcp",
+		Default("tcp").StringVar(&cfg.graphiteTransport)
-		"Transport protocol to use to communicate with Graphite. 'tcp', if empty.",
+	a.Flag("graphite-prefix", "The prefix to prepend to all metrics exported to Graphite. None, if empty.").
-	)
+		Default("").StringVar(&cfg.graphitePrefix)
-	flag.StringVar(&cfg.graphitePrefix, "graphite-prefix", "",
+	a.Flag("opentsdb-url", "The URL of the remote OpenTSDB server to send samples to. None, if empty.").
-		"The prefix to prepend to all metrics exported to Graphite. None, if empty.",
+		Default("").StringVar(&cfg.opentsdbURL)
-	)
+	a.Flag("influxdb-url", "The URL of the remote InfluxDB server to send samples to. None, if empty.").
-	flag.StringVar(&cfg.opentsdbURL, "opentsdb-url", "",
+		Default("").StringVar(&cfg.influxdbURL)
-		"The URL of the remote OpenTSDB server to send samples to. None, if empty.",
+	a.Flag("influxdb.retention-policy", "The InfluxDB retention policy to use.").
-	)
+		Default("autogen").StringVar(&cfg.influxdbRetentionPolicy)
-	flag.StringVar(&cfg.influxdbURL, "influxdb-url", "",
+	a.Flag("influxdb.username", "The username to use when sending samples to InfluxDB. The corresponding password must be provided via the INFLUXDB_PW environment variable.").
-		"The URL of the remote InfluxDB server to send samples to. None, if empty.",
+		Default("").StringVar(&cfg.influxdbUsername)
-	)
+	a.Flag("influxdb.database", "The name of the database to use for storing samples in InfluxDB.").
-	flag.StringVar(&cfg.influxdbRetentionPolicy, "influxdb.retention-policy", "autogen",
+		Default("prometheus").StringVar(&cfg.influxdbDatabase)
-		"The InfluxDB retention policy to use.",
+	a.Flag("send-timeout", "The timeout to use when sending samples to the remote storage.").
-	)
+		Default("30s").DurationVar(&cfg.remoteTimeout)
-	flag.StringVar(&cfg.influxdbUsername, "influxdb.username", "",
+	a.Flag("web.listen-address", "Address to listen on for web endpoints.").
-		"The username to use when sending samples to InfluxDB. The corresponding password must be provided via the INFLUXDB_PW environment variable.",
+		Default(":9201").StringVar(&cfg.listenAddr)
-	)
+	a.Flag("web.telemetry-path", "Address to listen on for web endpoints.").
-	flag.StringVar(&cfg.influxdbDatabase, "influxdb.database", "prometheus",
+		Default("/metrics").StringVar(&cfg.telemetryPath)
-		"The name of the database to use for storing samples in InfluxDB.",
-	)
-	flag.DurationVar(&cfg.remoteTimeout, "send-timeout", 30*time.Second,
-		"The timeout to use when sending samples to the remote storage.",
-	)
-	flag.StringVar(&cfg.listenAddr, "web.listen-address", ":9201", "Address to listen on for web endpoints.")
-	flag.StringVar(&cfg.telemetryPath, "web.telemetry-path", "/metrics", "Address to listen on for web endpoints.")
-	flag.StringVar(&cfg.logLevel, "log.level", "debug", "Only log messages with the given severity or above. One of: [debug, info, warn, error]")
 
-	flag.Parse()
+	flag.AddFlags(a, &cfg.promlogConfig)
+
+	_, err := a.Parse(os.Args[1:])
+	if err != nil {
+		fmt.Fprintln(os.Stderr, errors.Wrapf(err, "Error parsing commandline arguments"))
+		a.Usage(os.Args[1:])
+		os.Exit(2)
+	}
 
 	return cfg
 }

go.mod

@@ -103,7 +103,7 @@ require (
 	github.com/pmezard/go-difflib v0.0.0-20151028094244-d8ed2627bdf0 // indirect
 	github.com/prometheus/client_golang v0.0.0-20181001174001-0a8115f42e03
 	github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910
-	github.com/prometheus/common v0.0.0-20180518154759-7600349dcfe1
+	github.com/prometheus/common v0.0.0-20181119215939-b36ad289a3ea
 	github.com/prometheus/procfs v0.0.0-20160411190841-abf152e5f3e9 // indirect
 	github.com/prometheus/tsdb v0.2.0
 	github.com/rcrowley/go-metrics v0.0.0-20181016184325-3113b8401b8a // indirect

go.sum

@@ -211,8 +211,8 @@ github.com/prometheus/client_golang v0.0.0-20181001174001-0a8115f42e03 h1:716+Mw
 github.com/prometheus/client_golang v0.0.0-20181001174001-0a8115f42e03/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910 h1:idejC8f05m9MGOsuEi1ATq9shN03HrxNkD/luQvxCv8=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910/go.mod h1:MbSGuTsp3dbXC40dX6PRTWyKYBIrTGTE9sqQNg2J8bo=
-github.com/prometheus/common v0.0.0-20180518154759-7600349dcfe1 h1:osmNoEW2SCW3L7EX0km2LYM8HKpNWRiouxjE3XHkyGc=
+github.com/prometheus/common v0.0.0-20181119215939-b36ad289a3ea h1:4RkbEb5XX0Wvu3XhIW3zxgLUhUE9suNc7YLO52/RyT4=
-github.com/prometheus/common v0.0.0-20180518154759-7600349dcfe1/go.mod h1:daVV7qP5qjZbuso7PdcryaAu0sAZbrN9i7WWcTMWvro=
+github.com/prometheus/common v0.0.0-20181119215939-b36ad289a3ea/go.mod h1:daVV7qP5qjZbuso7PdcryaAu0sAZbrN9i7WWcTMWvro=
 github.com/prometheus/procfs v0.0.0-20160411190841-abf152e5f3e9 h1:IrO4Eb9oGw+GxzOhO4b2QC5EWO85Omh/4iTSPZktMm8=
 github.com/prometheus/procfs v0.0.0-20160411190841-abf152e5f3e9/go.mod h1:c3At6R/oaqEKCNdg8wHV1ftS6bRYblBhIjjI8uT2IGk=
 github.com/prometheus/tsdb v0.2.0 h1:27z98vFd/gPew17nmKEbLn37exGCwc2F5EyrgScg6bk=

vendor/github.com/prometheus/common/expfmt/text_create.go

@@ -14,13 +14,45 @@
 package expfmt
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"math"
+	"strconv"
 	"strings"
+	"sync"
+
+	"github.com/prometheus/common/model"
 
 	dto "github.com/prometheus/client_model/go"
-	"github.com/prometheus/common/model"
+)
+
+// enhancedWriter has all the enhanced write functions needed here. bytes.Buffer
+// implements it.
+type enhancedWriter interface {
+	io.Writer
+	WriteRune(r rune) (n int, err error)
+	WriteString(s string) (n int, err error)
+	WriteByte(c byte) error
+}
+
+const (
+	initialBufSize    = 512
+	initialNumBufSize = 24
+)
+
+var (
+	bufPool = sync.Pool{
+		New: func() interface{} {
+			return bytes.NewBuffer(make([]byte, 0, initialBufSize))
+		},
+	}
+	numBufPool = sync.Pool{
+		New: func() interface{} {
+			b := make([]byte, 0, initialNumBufSize)
+			return &b
+		},
+	}
 )
 
 // MetricFamilyToText converts a MetricFamily proto message into text format and
@@ -32,37 +64,92 @@ import (
 // will result in invalid text format output.
 //
 // This method fulfills the type 'prometheus.encoder'.
-func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
+func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err error) {
-	var written int
-
 	// Fail-fast checks.
 	if len(in.Metric) == 0 {
-		return written, fmt.Errorf("MetricFamily has no metrics: %s", in)
+		return 0, fmt.Errorf("MetricFamily has no metrics: %s", in)
 	}
 	name := in.GetName()
 	if name == "" {
-		return written, fmt.Errorf("MetricFamily has no name: %s", in)
+		return 0, fmt.Errorf("MetricFamily has no name: %s", in)
 	}
 
+	// Try the interface upgrade. If it doesn't work, we'll use a
+	// bytes.Buffer from the sync.Pool and write out its content to out in a
+	// single go in the end.
+	w, ok := out.(enhancedWriter)
+	if !ok {
+		b := bufPool.Get().(*bytes.Buffer)
+		b.Reset()
+		w = b
+		defer func() {
+			bWritten, bErr := out.Write(b.Bytes())
+			written = bWritten
+			if err == nil {
+				err = bErr
+			}
+			bufPool.Put(b)
+		}()
+	}
+
+	var n int
+
 	// Comments, first HELP, then TYPE.
 	if in.Help != nil {
-		n, err := fmt.Fprintf(
+		n, err = w.WriteString("# HELP ")
-			out, "# HELP %s %s\n",
-			name, escapeString(*in.Help, false),
-		)
 		written += n
 		if err != nil {
-			return written, err
+			return
 		}
+		n, err = w.WriteString(name)
+		written += n
+		if err != nil {
+			return
+		}
+		err = w.WriteByte(' ')
+		written++
+		if err != nil {
+			return
+		}
+		n, err = writeEscapedString(w, *in.Help, false)
+		written += n
+		if err != nil {
+			return
+		}
+		err = w.WriteByte('\n')
+		written++
+		if err != nil {
+			return
+		}
+	}
+	n, err = w.WriteString("# TYPE ")
+	written += n
+	if err != nil {
+		return
+	}
+	n, err = w.WriteString(name)
+	written += n
+	if err != nil {
+		return
 	}
 	metricType := in.GetType()
-	n, err := fmt.Fprintf(
+	switch metricType {
-		out, "# TYPE %s %s\n",
+	case dto.MetricType_COUNTER:
-		name, strings.ToLower(metricType.String()),
+		n, err = w.WriteString(" counter\n")
-	)
+	case dto.MetricType_GAUGE:
+		n, err = w.WriteString(" gauge\n")
+	case dto.MetricType_SUMMARY:
+		n, err = w.WriteString(" summary\n")
+	case dto.MetricType_UNTYPED:
+		n, err = w.WriteString(" untyped\n")
+	case dto.MetricType_HISTOGRAM:
+		n, err = w.WriteString(" histogram\n")
+	default:
+		return written, fmt.Errorf("unknown metric type %s", metricType.String())
+	}
 	written += n
 	if err != nil {
-		return written, err
+		return
 	}
 
 	// Finally the samples, one line for each.
@@ -75,9 +162,8 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
 				)
 			}
 			n, err = writeSample(
-				name, metric, "", "",
+				w, name, "", metric, "", 0,
 				metric.Counter.GetValue(),
-				out,
 			)
 		case dto.MetricType_GAUGE:
 			if metric.Gauge == nil {
@@ -86,9 +172,8 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
 				)
 			}
 			n, err = writeSample(
-				name, metric, "", "",
+				w, name, "", metric, "", 0,
 				metric.Gauge.GetValue(),
-				out,
 			)
 		case dto.MetricType_UNTYPED:
 			if metric.Untyped == nil {
@@ -97,9 +182,8 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
 				)
 			}
 			n, err = writeSample(
-				name, metric, "", "",
+				w, name, "", metric, "", 0,
 				metric.Untyped.GetValue(),
-				out,
 			)
 		case dto.MetricType_SUMMARY:
 			if metric.Summary == nil {
@@ -109,29 +193,26 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
 			}
 			for _, q := range metric.Summary.Quantile {
 				n, err = writeSample(
-					name, metric,
+					w, name, "", metric,
-					model.QuantileLabel, fmt.Sprint(q.GetQuantile()),
+					model.QuantileLabel, q.GetQuantile(),
 					q.GetValue(),
-					out,
 				)
 				written += n
 				if err != nil {
-					return written, err
+					return
 				}
 			}
 			n, err = writeSample(
-				name+"_sum", metric, "", "",
+				w, name, "_sum", metric, "", 0,
 				metric.Summary.GetSampleSum(),
-				out,
 			)
-			if err != nil {
-				return written, err
-			}
 			written += n
+			if err != nil {
+				return
+			}
 			n, err = writeSample(
-				name+"_count", metric, "", "",
+				w, name, "_count", metric, "", 0,
 				float64(metric.Summary.GetSampleCount()),
-				out,
 			)
 		case dto.MetricType_HISTOGRAM:
 			if metric.Histogram == nil {
@@ -140,46 +221,42 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
 				)
 			}
 			infSeen := false
-			for _, q := range metric.Histogram.Bucket {
+			for _, b := range metric.Histogram.Bucket {
 				n, err = writeSample(
-					name+"_bucket", metric,
+					w, name, "_bucket", metric,
-					model.BucketLabel, fmt.Sprint(q.GetUpperBound()),
+					model.BucketLabel, b.GetUpperBound(),
-					float64(q.GetCumulativeCount()),
+					float64(b.GetCumulativeCount()),
-					out,
 				)
 				written += n
 				if err != nil {
-					return written, err
+					return
 				}
-				if math.IsInf(q.GetUpperBound(), +1) {
+				if math.IsInf(b.GetUpperBound(), +1) {
 					infSeen = true
 				}
 			}
 			if !infSeen {
 				n, err = writeSample(
-					name+"_bucket", metric,
+					w, name, "_bucket", metric,
-					model.BucketLabel, "+Inf",
+					model.BucketLabel, math.Inf(+1),
 					float64(metric.Histogram.GetSampleCount()),
-					out,
 				)
-				if err != nil {
-					return written, err
-				}
 				written += n
+				if err != nil {
+					return
+				}
 			}
 			n, err = writeSample(
-				name+"_sum", metric, "", "",
+				w, name, "_sum", metric, "", 0,
 				metric.Histogram.GetSampleSum(),
-				out,
 			)
-			if err != nil {
-				return written, err
-			}
 			written += n
+			if err != nil {
+				return
+			}
 			n, err = writeSample(
-				name+"_count", metric, "", "",
+				w, name, "_count", metric, "", 0,
 				float64(metric.Histogram.GetSampleCount()),
-				out,
 			)
 		default:
 			return written, fmt.Errorf(
@@ -188,116 +265,204 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (int, error) {
 		}
 		written += n
 		if err != nil {
-			return written, err
+			return
 		}
 	}
-	return written, nil
+	return
 }
 
-// writeSample writes a single sample in text format to out, given the metric
+// writeSample writes a single sample in text format to w, given the metric
 // name, the metric proto message itself, optionally an additional label name
-// and value (use empty strings if not required), and the value. The function
+// with a float64 value (use empty string as label name if not required), and
-// returns the number of bytes written and any error encountered.
+// the value. The function returns the number of bytes written and any error
+// encountered.
 func writeSample(
-	name string,
+	w enhancedWriter,
+	name, suffix string,
 	metric *dto.Metric,
-	additionalLabelName, additionalLabelValue string,
+	additionalLabelName string, additionalLabelValue float64,
 	value float64,
-	out io.Writer,
 ) (int, error) {
 	var written int
-	n, err := fmt.Fprint(out, name)
+	n, err := w.WriteString(name)
 	written += n
 	if err != nil {
 		return written, err
 	}
-	n, err = labelPairsToText(
+	if suffix != "" {
-		metric.Label,
+		n, err = w.WriteString(suffix)
-		additionalLabelName, additionalLabelValue,
+		written += n
-		out,
+		if err != nil {
+			return written, err
+		}
+	}
+	n, err = writeLabelPairs(
+		w, metric.Label, additionalLabelName, additionalLabelValue,
 	)
 	written += n
 	if err != nil {
 		return written, err
 	}
-	n, err = fmt.Fprintf(out, " %v", value)
+	err = w.WriteByte(' ')
+	written++
+	if err != nil {
+		return written, err
+	}
+	n, err = writeFloat(w, value)
 	written += n
 	if err != nil {
 		return written, err
 	}
 	if metric.TimestampMs != nil {
-		n, err = fmt.Fprintf(out, " %v", *metric.TimestampMs)
+		err = w.WriteByte(' ')
+		written++
+		if err != nil {
+			return written, err
+		}
+		n, err = writeInt(w, *metric.TimestampMs)
 		written += n
 		if err != nil {
 			return written, err
 		}
 	}
-	n, err = out.Write([]byte{'\n'})
+	err = w.WriteByte('\n')
-	written += n
+	written++
 	if err != nil {
 		return written, err
 	}
 	return written, nil
 }
 
-// labelPairsToText converts a slice of LabelPair proto messages plus the
+// writeLabelPairs converts a slice of LabelPair proto messages plus the
 // explicitly given additional label pair into text formatted as required by the
-// text format and writes it to 'out'. An empty slice in combination with an
+// text format and writes it to 'w'. An empty slice in combination with an empty
-// empty string 'additionalLabelName' results in nothing being
+// string 'additionalLabelName' results in nothing being written. Otherwise, the
-// written. Otherwise, the label pairs are written, escaped as required by the
+// label pairs are written, escaped as required by the text format, and enclosed
-// text format, and enclosed in '{...}'. The function returns the number of
+// in '{...}'. The function returns the number of bytes written and any error
-// bytes written and any error encountered.
+// encountered.
-func labelPairsToText(
+func writeLabelPairs(
+	w enhancedWriter,
 	in []*dto.LabelPair,
-	additionalLabelName, additionalLabelValue string,
+	additionalLabelName string, additionalLabelValue float64,
-	out io.Writer,
 ) (int, error) {
 	if len(in) == 0 && additionalLabelName == "" {
 		return 0, nil
 	}
-	var written int
+	var (
-	separator := '{'
+		written   int
-	for _, lp := range in {
+		separator byte = '{'
-		n, err := fmt.Fprintf(
-			out, `%c%s="%s"`,
-			separator, lp.GetName(), escapeString(lp.GetValue(), true),
 	)
+	for _, lp := range in {
+		err := w.WriteByte(separator)
+		written++
+		if err != nil {
+			return written, err
+		}
+		n, err := w.WriteString(lp.GetName())
 		written += n
 		if err != nil {
 			return written, err
 		}
+		n, err = w.WriteString(`="`)
+		written += n
+		if err != nil {
+			return written, err
+		}
+		n, err = writeEscapedString(w, lp.GetValue(), true)
+		written += n
+		if err != nil {
+			return written, err
+		}
+		err = w.WriteByte('"')
+		written++
+		if err != nil {
+			return written, err
+		}
 		separator = ','
 	}
 	if additionalLabelName != "" {
-		n, err := fmt.Fprintf(
+		err := w.WriteByte(separator)
-			out, `%c%s="%s"`,
+		written++
-			separator, additionalLabelName,
+		if err != nil {
-			escapeString(additionalLabelValue, true),
+			return written, err
-		)
+		}
+		n, err := w.WriteString(additionalLabelName)
 		written += n
 		if err != nil {
 			return written, err
 		}
-	}
+		n, err = w.WriteString(`="`)
-	n, err := out.Write([]byte{'}'})
 		written += n
 		if err != nil {
 			return written, err
 		}
+		n, err = writeFloat(w, additionalLabelValue)
+		written += n
+		if err != nil {
+			return written, err
+		}
+		err = w.WriteByte('"')
+		written++
+		if err != nil {
+			return written, err
+		}
+	}
+	err := w.WriteByte('}')
+	written++
+	if err != nil {
+		return written, err
+	}
 	return written, nil
 }
 
+// writeEscapedString replaces '\' by '\\', new line character by '\n', and - if
+// includeDoubleQuote is true - '"' by '\"'.
 var (
-	escape                = strings.NewReplacer("\\", `\\`, "\n", `\n`)
+	escaper       = strings.NewReplacer("\\", `\\`, "\n", `\n`)
-	escapeWithDoubleQuote = strings.NewReplacer("\\", `\\`, "\n", `\n`, "\"", `\"`)
+	quotedEscaper = strings.NewReplacer("\\", `\\`, "\n", `\n`, "\"", `\"`)
 )
 
-// escapeString replaces '\' by '\\', new line character by '\n', and - if
+func writeEscapedString(w enhancedWriter, v string, includeDoubleQuote bool) (int, error) {
-// includeDoubleQuote is true - '"' by '\"'.
-func escapeString(v string, includeDoubleQuote bool) string {
 	if includeDoubleQuote {
-		return escapeWithDoubleQuote.Replace(v)
+		return quotedEscaper.WriteString(w, v)
+	} else {
+		return escaper.WriteString(w, v)
+	}
 }
 
-	return escape.Replace(v)
+// writeFloat is equivalent to fmt.Fprint with a float64 argument but hardcodes
+// a few common cases for increased efficiency. For non-hardcoded cases, it uses
+// strconv.AppendFloat to avoid allocations, similar to writeInt.
+func writeFloat(w enhancedWriter, f float64) (int, error) {
+	switch {
+	case f == 1:
+		return 1, w.WriteByte('1')
+	case f == 0:
+		return 1, w.WriteByte('0')
+	case f == -1:
+		return w.WriteString("-1")
+	case math.IsNaN(f):
+		return w.WriteString("NaN")
+	case math.IsInf(f, +1):
+		return w.WriteString("+Inf")
+	case math.IsInf(f, -1):
+		return w.WriteString("-Inf")
+	default:
+		bp := numBufPool.Get().(*[]byte)
+		*bp = strconv.AppendFloat((*bp)[:0], f, 'g', -1, 64)
+		written, err := w.Write(*bp)
+		numBufPool.Put(bp)
+		return written, err
+	}
+}
+
+// writeInt is equivalent to fmt.Fprint with an int64 argument but uses
+// strconv.AppendInt with a byte slice taken from a sync.Pool to avoid
+// allocations.
+func writeInt(w enhancedWriter, i int64) (int, error) {
+	bp := numBufPool.Get().(*[]byte)
+	*bp = strconv.AppendInt((*bp)[:0], i, 10)
+	written, err := w.Write(*bp)
+	numBufPool.Put(bp)
+	return written, err
 }

vendor/github.com/prometheus/common/expfmt/text_parse.go

@@ -359,7 +359,7 @@ func (p *TextParser) startLabelValue() stateFn {
 		}
 		return p.readingValue
 	default:
-		p.parseError(fmt.Sprintf("unexpected end of label value %q", p.currentLabelPair.Value))
+		p.parseError(fmt.Sprintf("unexpected end of label value %q", p.currentLabelPair.GetValue()))
 		return nil
 	}
 }

vendor/github.com/prometheus/common/model/time.go

@@ -43,7 +43,7 @@ const (
 // (1970-01-01 00:00 UTC) excluding leap seconds.
 type Time int64
 
-// Interval describes and interval between two timestamps.
+// Interval describes an interval between two timestamps.
 type Interval struct {
 	Start, End Time
 }

vendor/github.com/prometheus/common/promlog/flag/flag.go

@@ -25,9 +25,21 @@ const LevelFlagName = "log.level"
 // LevelFlagHelp is the help description for the log.level flag.
 const LevelFlagHelp = "Only log messages with the given severity or above. One of: [debug, info, warn, error]"
 
+// FormatFlagName is the canonical flag name to configure the log format
+// within Prometheus projects.
+const FormatFlagName = "log.format"
+
+// FormatFlagHelp is the help description for the log.format flag.
+const FormatFlagHelp = "Output format of log messages. One of: [logfmt, json]"
+
 // AddFlags adds the flags used by this package to the Kingpin application.
 // To use the default Kingpin application, call AddFlags(kingpin.CommandLine)
-func AddFlags(a *kingpin.Application, logLevel *promlog.AllowedLevel) {
+func AddFlags(a *kingpin.Application, config *promlog.Config) {
+	config.Level = &promlog.AllowedLevel{}
 	a.Flag(LevelFlagName, LevelFlagHelp).
-		Default("info").SetValue(logLevel)
+		Default("info").SetValue(config.Level)
+
+	config.Format = &promlog.AllowedFormat{}
+	a.Flag(FormatFlagName, FormatFlagHelp).
+		Default("logfmt").SetValue(config.Format)
 }

vendor/github.com/prometheus/common/promlog/log.go

@@ -53,11 +53,43 @@ func (l *AllowedLevel) Set(s string) error {
 	return nil
 }
 
-// New returns a new leveled oklog logger in the logfmt format. Each logged line will be annotated
+// AllowedFormat is a settable identifier for the output format that the logger can have.
+type AllowedFormat struct {
+	s string
+}
+
+func (f *AllowedFormat) String() string {
+	return f.s
+}
+
+// Set updates the value of the allowed format.
+func (f *AllowedFormat) Set(s string) error {
+	switch s {
+	case "logfmt", "json":
+		f.s = s
+	default:
+		return errors.Errorf("unrecognized log format %q", s)
+	}
+	return nil
+}
+
+// Config is a struct containing configurable settings for the logger
+type Config struct {
+	Level  *AllowedLevel
+	Format *AllowedFormat
+}
+
+// New returns a new leveled oklog logger. Each logged line will be annotated
 // with a timestamp. The output always goes to stderr.
-func New(al AllowedLevel) log.Logger {
+func New(config *Config) log.Logger {
-	l := log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr))
+	var l log.Logger
-	l = level.NewFilter(l, al.o)
+	if config.Format.s == "logfmt" {
+		l = log.NewLogfmtLogger(log.NewSyncWriter(os.Stderr))
+	} else {
+		l = log.NewJSONLogger(log.NewSyncWriter(os.Stderr))
+	}
+
+	l = level.NewFilter(l, config.Level.o)
 	l = log.With(l, "ts", log.DefaultTimestampUTC, "caller", log.DefaultCaller)
 	return l
 }

vendor/github.com/prometheus/common/route/route.go

@@ -1,10 +1,10 @@
 package route
 
 import (
+	"context"
 	"net/http"
 
 	"github.com/julienschmidt/httprouter"
-	"golang.org/x/net/context"
 )
 
 type param string

vendor/modules.txt

@@ -175,7 +175,7 @@ github.com/prometheus/client_golang/prometheus/promhttp
 github.com/prometheus/client_golang/prometheus/internal
 # github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910
 github.com/prometheus/client_model/go
-# github.com/prometheus/common v0.0.0-20180518154759-7600349dcfe1
+# github.com/prometheus/common v0.0.0-20181119215939-b36ad289a3ea
 github.com/prometheus/common/model
 github.com/prometheus/common/promlog
 github.com/prometheus/common/promlog/flag

web/api/v1/api_test.go

@@ -272,7 +272,14 @@ func TestEndpoints(t *testing.T) {
 
 		al := promlog.AllowedLevel{}
 		al.Set("debug")
-		remote := remote.NewStorage(promlog.New(al), func() (int64, error) {
+		af := promlog.AllowedFormat{}
+		al.Set("logfmt")
+		promlogConfig := promlog.Config{
+			Level:  &al,
+			Format: &af,
+		}
+
+		remote := remote.NewStorage(promlog.New(&promlogConfig), func() (int64, error) {
 			return 0, nil
 		}, 1*time.Second)