mirror of https://github.com/divan/expvarmon.git
131 lines
2.7 KiB
Go
131 lines
2.7 KiB
Go
package main
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import (
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"net/url"
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"strings"
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"sync"
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"github.com/antonholmquist/jason"
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)
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var (
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// uptimeCounter is a variable used for tracking uptime status.
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// It should be always incrementing and included into default expvar vars.
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// Could be replaced with something different or made configurable in
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// the future.
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uptimeCounter = VarName("memstats.PauseTotalNs").ToSlice()
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)
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// Service represents constantly updating info about single service.
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type Service struct {
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URL url.URL
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Name string
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Cmdline string
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Vars map[VarName]Var
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Err error
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Restarted bool
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UptimeCounter int64
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}
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// NewService returns new Service object.
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func NewService(url url.URL, varNames []VarName) *Service {
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vars := make(map[VarName]Var)
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for _, name := range varNames {
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v := NewVar(name)
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vars[name] = v
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}
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return &Service{
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Name: url.Host, // we have only port on start, so use it as name until resolved
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URL: url,
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Vars: vars,
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}
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}
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// Update updates Service info from Expvar variable.
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func (s *Service) Update(wg *sync.WaitGroup) {
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defer wg.Done()
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expvar, err := FetchExpvar(s.URL)
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// check for restart
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if s.Err != nil && err == nil {
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s.Restarted = true
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}
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s.Err = err
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// if memstat.PauseTotalNs less than s.UptimeCounter
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// then service was restarted
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c, err := expvar.GetInt64(uptimeCounter...)
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if err != nil {
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s.Err = err
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} else {
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if s.UptimeCounter > c {
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s.Restarted = true
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}
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s.UptimeCounter = c
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}
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// Update Cmdline & Name only once
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if len(s.Cmdline) == 0 {
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cmdline, err := expvar.GetStringArray("cmdline")
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if err != nil {
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s.Err = err
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} else {
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s.Cmdline = strings.Join(cmdline, " ")
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s.Name = BaseCommand(cmdline)
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}
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}
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// For all vars, fetch desired value from JSON
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for name, v := range s.Vars {
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value, err := expvar.GetValue(name.ToSlice()...)
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if err != nil {
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v.Set(nil)
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}
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v.Set(value)
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}
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}
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// guessValue attemtps to bruteforce all supported types.
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// TODO: FIXME: remove this func
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func guessValue(value *jason.Value) interface{} {
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if v, err := value.Int64(); err == nil {
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return v
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} else if v, err := value.Float64(); err == nil {
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return v
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} else if v, err := value.Boolean(); err == nil {
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return v
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} else if v, err := value.String(); err == nil {
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return v
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} else if v, err := value.Array(); err == nil {
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// if we get an array, calculate average
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// empty array, treat as zero
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if len(v) == 0 {
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return 0
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}
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avg := averageJason(v)
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// cast to int64 for Int64 values
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if _, err := v[0].Int64(); err == nil {
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return int64(avg)
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}
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return avg
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}
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return nil
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}
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// Value returns current value for the given varable of this service.
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func (s Service) Value(name VarName) string {
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v, ok := s.Vars[name]
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if !ok {
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return ""
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}
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return v.String()
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}
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