Add Prometheus http handler for metrics

Metrics are: connection counts, active IP addresses, DNS addresses,
FastDP flow metrics, connection termination count

.gitmodules

@@ -82,3 +82,24 @@
 [submodule "vendor/github.com/weaveworks/docker"]
 	path = vendor/github.com/weaveworks/docker
 	url = https://github.com/weaveworks/docker
+[submodule "vendor/github.com/beorn7/perks"]
+	path = vendor/github.com/beorn7/perks
+	url = https://github.com/beorn7/perks
+[submodule "vendor/github.com/prometheus/procfs"]
+	path = vendor/github.com/prometheus/procfs
+	url = https://github.com/prometheus/procfs
+[submodule "vendor/github.com/prometheus/client_golang"]
+	path = vendor/github.com/prometheus/client_golang
+	url = https://github.com/prometheus/client_golang
+[submodule "vendor/github.com/prometheus/client_model"]
+	path = vendor/github.com/prometheus/client_model
+	url = https://github.com/prometheus/client_model
+[submodule "vendor/github.com/prometheus/common"]
+	path = vendor/github.com/prometheus/common
+	url = https://github.com/prometheus/common
+[submodule "vendor/github.com/golang/protobuf"]
+	path = vendor/github.com/golang/protobuf
+	url = https://github.com/golang/protobuf
+[submodule "vendor/github.com/matttproud/golang_protobuf_extensions"]
+	path = vendor/github.com/matttproud/golang_protobuf_extensions
+	url = https://github.com/matttproud/golang_protobuf_extensions

prog/weaver/http.go

@@ -121,6 +121,16 @@ func countDNSEntries(entries []nameserver.EntryStatus) int {
 	return count
 }
 
+func countDNSEntriesForPeer(peername string, entries []nameserver.EntryStatus) int {
+	count := 0
+	for _, entry := range entries {
+		if entry.Tombstone == 0 && entry.Origin == peername {
+			count++
+		}
+	}
+	return count
+}
+
 // Print counts in a specified order
 func printCounts(counts map[string]int, keys []string) string {
 	var stringCounts []string
@@ -322,4 +332,6 @@ func HandleHTTP(muxRouter *mux.Router, version string, router *weave.NetworkRout
 	defHandler("/status/peers", peersTemplate)
 	defHandler("/status/dns", dnsEntriesTemplate)
 	defHandler("/status/ipam", ipamTemplate)
+
+	muxRouter.Methods("GET").Path("/metrics").Handler(metricsHandler(router, allocator, ns))
 }

prog/weaver/metrics.go

@@ -0,0 +1,129 @@
+package main
+
+import (
+	"net/http"
+	"os"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+
+	"github.com/weaveworks/weave/ipam"
+	"github.com/weaveworks/weave/nameserver"
+	"github.com/weaveworks/weave/net/address"
+	weave "github.com/weaveworks/weave/router"
+)
+
+func metricsHandler(router *weave.NetworkRouter, allocator *ipam.Allocator, ns *nameserver.Nameserver, dnsserver *nameserver.DNSServer) http.Handler {
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(prometheus.NewProcessCollector(os.Getpid(), ""))
+	reg.MustRegister(newMetrics(router, allocator, ns, dnsserver))
+	return promhttp.HandlerFor(reg, promhttp.HandlerOpts{})
+}
+
+type collector struct {
+	router    *weave.NetworkRouter
+	allocator *ipam.Allocator
+	ns        *nameserver.Nameserver
+	dnsserver *nameserver.DNSServer
+}
+
+type metric struct {
+	*prometheus.Desc
+	Collect func(WeaveStatus, *prometheus.Desc, chan<- prometheus.Metric)
+}
+
+func desc(fqName, help string, variableLabels ...string) *prometheus.Desc {
+	return prometheus.NewDesc(fqName, help, variableLabels, prometheus.Labels{})
+}
+
+func intGauge(desc *prometheus.Desc, val int, labels ...string) prometheus.Metric {
+	return prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, float64(val), labels...)
+}
+func uint64Counter(desc *prometheus.Desc, val uint64, labels ...string) prometheus.Metric {
+	return prometheus.MustNewConstMetric(desc, prometheus.CounterValue, float64(val), labels...)
+}
+
+var metrics []metric = []metric{
+	{desc("weave_connections", "Number of peer-to-peer connections.", "state"),
+		func(s WeaveStatus, desc *prometheus.Desc, ch chan<- prometheus.Metric) {
+			established := 0
+			for _, conn := range s.Router.Connections {
+				if conn.State == "established" {
+					established++
+				}
+			}
+
+			ch <- intGauge(desc, len(s.Router.Connections)-established, "non-established")
+			ch <- intGauge(desc, established, "established")
+		}},
+	{desc("weave_connection_termination_count", "Number of peer-to-peer connections terminated."),
+		func(s WeaveStatus, desc *prometheus.Desc, ch chan<- prometheus.Metric) {
+			ch <- uint64Counter(desc, uint64(s.Router.TerminationCount))
+		}},
+	{desc("weave_ips", "Number of IP addresses.", "state"),
+		func(s WeaveStatus, desc *prometheus.Desc, ch chan<- prometheus.Metric) {
+			ch <- intGauge(desc, s.IPAM.RangeNumIPs, "total")
+			ch <- intGauge(desc, s.IPAM.ActiveIPs, "local-used")
+		}},
+	{desc("weave_dns_entries", "Number of DNS entries.", "state"),
+		func(s WeaveStatus, desc *prometheus.Desc, ch chan<- prometheus.Metric) {
+			ch <- intGauge(desc, countDNSEntries(s.DNS.Entries), "total")
+			ch <- intGauge(desc, countDNSEntriesForPeer(s.Router.Name, s.DNS.Entries), "local")
+		}},
+	{desc("weave_flows", "Number of FastDP flows."),
+		func(s WeaveStatus, desc *prometheus.Desc, ch chan<- prometheus.Metric) {
+			if metrics := fastDPMetrics(s); metrics != nil {
+				ch <- intGauge(desc, metrics.Flows)
+			}
+		}},
+	{desc("weave_packets_total", "Number of packets transferred.", "flow"),
+		func(s WeaveStatus, desc *prometheus.Desc, ch chan<- prometheus.Metric) {
+			if metrics := fastDPMetrics(s); metrics != nil {
+				ch <- uint64Counter(desc, metrics.TotalPackets, "total")
+			}
+		}},
+	{desc("weave_bytes_total", "Number of bytes transferred.", "flow"),
+		func(s WeaveStatus, desc *prometheus.Desc, ch chan<- prometheus.Metric) {
+			if metrics := fastDPMetrics(s); metrics != nil {
+				ch <- uint64Counter(desc, metrics.TotalBytes, "total")
+			}
+		}},
+}
+
+func fastDPMetrics(s WeaveStatus) *weave.FastDPMetrics {
+	if reporter, ok := s.Router.OverlayDiagnostics.(weave.MetricsReporter); ok {
+		if metrics := reporter.Metrics(); metrics != nil {
+			if fastdpMetrics, ok := metrics.(*weave.FastDPMetrics); ok {
+				return fastdpMetrics
+			}
+		}
+	}
+	return nil
+}
+
+func newMetrics(router *weave.NetworkRouter, allocator *ipam.Allocator, ns *nameserver.Nameserver, dnsserver *nameserver.DNSServer) *collector {
+	return &collector{
+		router:    router,
+		allocator: allocator,
+		ns:        ns,
+		dnsserver: dnsserver,
+	}
+}
+
+func (m *collector) Collect(ch chan<- prometheus.Metric) {
+
+	status := WeaveStatus{"", nil,
+		weave.NewNetworkRouterStatus(m.router),
+		ipam.NewStatus(m.allocator, address.CIDR{}),
+		nameserver.NewStatus(m.ns, m.dnsserver)}
+
+	for _, metric := range metrics {
+		metric.Collect(status, metric.Desc, ch)
+	}
+}
+
+func (m *collector) Describe(ch chan<- *prometheus.Desc) {
+	for _, metric := range metrics {
+		ch <- metric.Desc
+	}
+}