varz/varz.go

   1 // Exports runtime variables using prometheus.
   2 package varz
   3
   4 import (
   5         "bufio"
   6         "flag"
   7         "fmt"
   8         "log"
   9         "os"
  10         "runtime"
  11         "strings"
  12         "syscall"
  13
  14         "github.com/prometheus/client_golang/prometheus"
  15 )
  16
  17 var (
  18         availFS = flag.String("varz_avail_fs",
  19                 "/srv/dcs",
  20                 "If non-empty, /varz will contain the number of available bytes on the specified filesystem")
  21 )
  22
  23 const (
  24         bytesPerSector = 512
  25 )
  26
  27 var (
  28         memAllocBytesGauge = prometheus.NewGaugeFunc(
  29                 prometheus.GaugeOpts{
  30                         Subsystem: "process",
  31                         Name:      "mem_alloc_bytes",
  32                         Help:      "Bytes allocated and still in use.",
  33                 },
  34                 func() float64 {
  35                         var m runtime.MemStats
  36                         runtime.ReadMemStats(&m)
  37                         return float64(m.Alloc)
  38                 },
  39         )
  40
  41         availFSGauge = prometheus.NewGaugeFunc(
  42                 prometheus.GaugeOpts{
  43                         Name: "avail_fs_bytes",
  44                         Help: "Number of available bytes on -varz_avail_fs.",
  45                 },
  46                 func() float64 {
  47                         if *availFS != "" {
  48                                 var stat syscall.Statfs_t
  49                                 if err := syscall.Statfs(*availFS, &stat); err != nil {
  50                                         log.Printf("Could not stat filesystem for %q: %v\n", *availFS, err)
  51                                 } else {
  52                                         return float64(stat.Bavail * uint64(stat.Bsize))
  53                                 }
  54                         }
  55                         return 0
  56                 },
  57         )
  58 )
  59
  60 type cpuTimeMetric struct {
  61         desc *prometheus.Desc
  62 }
  63
  64 func (ct *cpuTimeMetric) Describe(ch chan<- *prometheus.Desc) {
  65         ch <- ct.desc
  66 }
  67
  68 func (ct cpuTimeMetric) Collect(ch chan<- prometheus.Metric) {
  69         var rusage syscall.Rusage
  70         if err := syscall.Getrusage(syscall.RUSAGE_SELF, &rusage); err == nil {
  71                 ch <- prometheus.MustNewConstMetric(ct.desc, prometheus.CounterValue, float64(syscall.TimevalToNsec(rusage.Utime)), "user")
  72
  73                 ch <- prometheus.MustNewConstMetric(ct.desc, prometheus.CounterValue, float64(syscall.TimevalToNsec(rusage.Stime)), "system")
  74         }
  75 }
  76
  77 type diskStatsMetric struct {
  78         reads        *prometheus.Desc
  79         writes       *prometheus.Desc
  80         readbytes    *prometheus.Desc
  81         writtenbytes *prometheus.Desc
  82 }
  83
  84 func (ct *diskStatsMetric) Describe(ch chan<- *prometheus.Desc) {
  85         ch <- ct.reads
  86         ch <- ct.writes
  87         ch <- ct.readbytes
  88         ch <- ct.writtenbytes
  89 }
  90
  91 func (ct diskStatsMetric) Collect(ch chan<- prometheus.Metric) {
  92         diskstats, err := os.Open("/proc/diskstats")
  93         if err != nil {
  94                 return
  95         }
  96         defer diskstats.Close()
  97
  98         scanner := bufio.NewScanner(diskstats)
  99         for scanner.Scan() {
 100                 // From http://sources.debian.net/src/linux/3.16.7-2/block/genhd.c/?hl=1141#L1141
 101                 // seq_printf(seqf, "%4d %7d %s %lu %lu %lu %u %lu %lu %lu %u %u %u %u\n",
 102                 var major, minor uint64
 103                 var device string
 104                 var reads, mergedreads, readsectors, readms uint64
 105                 var writes, mergedwrites, writtensectors, writems uint64
 106                 var inflight, ioticks, timeinqueue uint64
 107                 fmt.Sscanf(scanner.Text(), "%4d %7d %s %d %d %d %d %d %d %d %d %d %d %d",
 108                         &major, &minor, &device,
 109                         &reads, &mergedreads, &readsectors, &readms,
 110                         &writes, &mergedwrites, &writtensectors, &writems,
 111                         &inflight, &ioticks, &timeinqueue)
 112                 // Matches sda, xvda, nvme0n1, …
 113                 if !strings.HasSuffix(device, "da") &&
 114                         !strings.HasSuffix(device, "n1") {
 115                         continue
 116                 }
 117                 ch <- prometheus.MustNewConstMetric(ct.reads, prometheus.CounterValue, float64(reads), device)
 118                 ch <- prometheus.MustNewConstMetric(ct.writes, prometheus.CounterValue, float64(writes), device)
 119                 ch <- prometheus.MustNewConstMetric(ct.readbytes, prometheus.CounterValue, float64(readsectors*bytesPerSector), device)
 120                 ch <- prometheus.MustNewConstMetric(ct.writtenbytes, prometheus.CounterValue, float64(writtensectors*bytesPerSector), device)
 121         }
 122 }
 123
 124 func init() {
 125         prometheus.MustRegister(memAllocBytesGauge)
 126         prometheus.MustRegister(availFSGauge)
 127
 128         prometheus.MustRegister(&cpuTimeMetric{
 129                 desc: prometheus.NewDesc("process_cpu_nsec",
 130                         "CPU time spent in ns, split by user/system.",
 131                         []string{"mode"},
 132                         nil),
 133         })
 134
 135         prometheus.MustRegister(&diskStatsMetric{
 136                 reads: prometheus.NewDesc("system_disk_reads",
 137                         "Disk reads, per device name (e.g. xvda).",
 138                         []string{"device"},
 139                         nil),
 140
 141                 writes: prometheus.NewDesc("system_disk_writes",
 142                         "Disk writes, per device name (e.g. xvda).",
 143                         []string{"device"},
 144                         nil),
 145
 146                 readbytes: prometheus.NewDesc("disk_read_bytes",
 147                         "Bytes read from disk, per device name (e.g. xvda).",
 148                         []string{"device"},
 149                         nil),
 150
 151                 writtenbytes: prometheus.NewDesc("disk_written_bytes",
 152                         "Bytes written to disk, per device name (e.g. xvda).",
 153                         []string{"device"},
 154                         nil),
 155         })
 156 }
 157
 158 // vim:ts=4:sw=4:noexpandtab