status-im/status-go

package node

import (
    "errors"
    "strings"

    "github.com/ethereum/go-ethereum/node"
    "github.com/ethereum/go-ethereum/p2p"

    prom "github.com/prometheus/client_golang/prometheus"
)

var (
    nodePeersGauge = prom.NewGaugeVec(prom.GaugeOpts{
        Name: "p2p_peers_count",
        Help: "Current numbers of peers split by name.",
    }, []string{"type", "version", "platform"})
    nodePeersAbsolute = prom.NewGauge(prom.GaugeOpts{
        Name: "p2p_peers_absolute",
        Help: "Absolute number of connected peers.",
    })
    nodeMaxPeersGauge = prom.NewGauge(prom.GaugeOpts{
        Name: "p2p_peers_max",
        Help: "Maximum number of peers that can connect.",
    })
)

func init() {
    prom.MustRegister(nodePeersGauge)
    prom.MustRegister(nodePeersAbsolute)
    prom.MustRegister(nodeMaxPeersGauge)
}

func updateNodeMetrics(node *node.Node, evType p2p.PeerEventType) error {
    server := node.Server()
    if server == nil {
        return errors.New("p2p server is unavailable")
    }

    calculatePeerCounts(server)
    nodePeersAbsolute.Set(float64(server.PeerCount()))
    nodeMaxPeersGauge.Set(float64(server.MaxPeers))

    return nil
}

func labelsFromNodeName(name string) (prom.Labels, error) {
    tokens := strings.Split(name, "/")
    if len(tokens) == 4 {
        return prom.Labels{
            "type":     tokens[0],
            "version":  tokens[1],
            "platform": tokens[2],
        }, nil
    } else if len(tokens) == 3 {
        return prom.Labels{
            "type":     tokens[0],
            "version":  "unknown",
            "platform": tokens[1],
        }, nil
    } else {
        return nil, errors.New("wrong number of segments in name")
    }
}

func calculatePeerCounts(server *p2p.Server) {
    peers := server.Peers()
    /* necessary to count all peers anew */
    nodePeersGauge.Reset()

    for _, p := range peers {
        labels, err := labelsFromNodeName(p.Fullname())
        if err != nil {
            logger.Warn("failed parsing peer name", "error", err, "name", p.Name())
            continue
        }
        nodePeersGauge.With(labels).Inc()
    }
}