swarm: initial instrumentation (#15969)

* swarm: initial instrumentation with go-metrics

* swarm: initialise metrics collection and add ResettingTimer to HTTP requests

* swarm: update metrics flags names. remove redundant Timer.

* swarm: rename method for periodically updating gauges

* swarm: finalise metrics after feedback

* swarm/network: always init kad metrics containers

* swarm/network: off-by-one index in metrics containers

* swarm, metrics: resolved conflicts

swarm/metrics/flags.go

@@ -0,0 +1,82 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package metrics
+
+import (
+	"time"
+
+	"github.com/ethereum/go-ethereum/cmd/utils"
+	"github.com/ethereum/go-ethereum/log"
+	gethmetrics "github.com/ethereum/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/metrics/influxdb"
+	"gopkg.in/urfave/cli.v1"
+)
+
+var (
+	metricsInfluxDBEndpointFlag = cli.StringFlag{
+		Name:  "metrics.influxdb.endpoint",
+		Usage: "Metrics InfluxDB endpoint",
+		Value: "http://127.0.0.1:8086",
+	}
+	metricsInfluxDBDatabaseFlag = cli.StringFlag{
+		Name:  "metrics.influxdb.database",
+		Usage: "metrics InfluxDB database",
+		Value: "metrics",
+	}
+	metricsInfluxDBUsernameFlag = cli.StringFlag{
+		Name:  "metrics.influxdb.username",
+		Usage: "metrics InfluxDB username",
+		Value: "",
+	}
+	metricsInfluxDBPasswordFlag = cli.StringFlag{
+		Name:  "metrics.influxdb.password",
+		Usage: "metrics InfluxDB password",
+		Value: "",
+	}
+	// The `host` tag is part of every measurement sent to InfluxDB. Queries on tags are faster in InfluxDB.
+	// It is used so that we can group all nodes and average a measurement across all of them, but also so
+	// that we can select a specific node and inspect its measurements.
+	// https://docs.influxdata.com/influxdb/v1.4/concepts/key_concepts/#tag-key
+	metricsInfluxDBHostTagFlag = cli.StringFlag{
+		Name:  "metrics.influxdb.host.tag",
+		Usage: "metrics InfluxDB `host` tag attached to all measurements",
+		Value: "localhost",
+	}
+)
+
+// Flags holds all command-line flags required for metrics collection.
+var Flags = []cli.Flag{
+	utils.MetricsEnabledFlag,
+	metricsInfluxDBEndpointFlag, metricsInfluxDBDatabaseFlag, metricsInfluxDBUsernameFlag, metricsInfluxDBPasswordFlag, metricsInfluxDBHostTagFlag,
+}
+
+func Setup(ctx *cli.Context) {
+	if gethmetrics.Enabled {
+		var (
+			endpoint = ctx.GlobalString(metricsInfluxDBEndpointFlag.Name)
+			database = ctx.GlobalString(metricsInfluxDBDatabaseFlag.Name)
+			username = ctx.GlobalString(metricsInfluxDBUsernameFlag.Name)
+			password = ctx.GlobalString(metricsInfluxDBPasswordFlag.Name)
+			hosttag  = ctx.GlobalString(metricsInfluxDBHostTagFlag.Name)
+		)
+
+		log.Info("Enabling swarm metrics collection and export")
+		go influxdb.InfluxDBWithTags(gethmetrics.DefaultRegistry, 10*time.Second, endpoint, database, username, password, "swarm.", map[string]string{
+			"host": hosttag,
+		})
+	}
+}