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agent.go
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agent.go
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package agent
import (
"fmt"
"log"
"os"
"runtime"
"sync"
"time"
"github.com/influxdata/telegraf"
"github.com/influxdata/telegraf/internal"
"github.com/influxdata/telegraf/internal/config"
"github.com/influxdata/telegraf/internal/models"
)
// Agent runs telegraf and collects data based on the given config
type Agent struct {
Config *config.Config
}
// NewAgent returns an Agent struct based off the given Config
func NewAgent(config *config.Config) (*Agent, error) {
a := &Agent{
Config: config,
}
if !a.Config.Agent.OmitHostname {
if a.Config.Agent.Hostname == "" {
hostname, err := os.Hostname()
if err != nil {
return nil, err
}
a.Config.Agent.Hostname = hostname
}
config.Tags["host"] = a.Config.Agent.Hostname
}
return a, nil
}
// Connect connects to all configured outputs
func (a *Agent) Connect() error {
for _, o := range a.Config.Outputs {
o.Quiet = a.Config.Agent.Quiet
switch ot := o.Output.(type) {
case telegraf.ServiceOutput:
if err := ot.Start(); err != nil {
log.Printf("E! Service for output %s failed to start, exiting\n%s\n",
o.Name, err.Error())
return err
}
}
log.Printf("D! Attempting connection to output: %s\n", o.Name)
err := o.Output.Connect()
if err != nil {
log.Printf("E! Failed to connect to output %s, retrying in 15s, "+
"error was '%s' \n", o.Name, err)
time.Sleep(15 * time.Second)
err = o.Output.Connect()
if err != nil {
return err
}
}
log.Printf("D! Successfully connected to output: %s\n", o.Name)
}
return nil
}
// Close closes the connection to all configured outputs
func (a *Agent) Close() error {
var err error
for _, o := range a.Config.Outputs {
err = o.Output.Close()
switch ot := o.Output.(type) {
case telegraf.ServiceOutput:
ot.Stop()
}
}
return err
}
func panicRecover(input *models.RunningInput) {
if err := recover(); err != nil {
trace := make([]byte, 2048)
runtime.Stack(trace, true)
log.Printf("E! FATAL: Input [%s] panicked: %s, Stack:\n%s\n",
input.Name(), err, trace)
log.Println("E! PLEASE REPORT THIS PANIC ON GITHUB with " +
"stack trace, configuration, and OS information: " +
"https://github.com/influxdata/telegraf/issues/new")
}
}
// gatherer runs the inputs that have been configured with their own
// reporting interval.
func (a *Agent) gatherer(
shutdown chan struct{},
input *models.RunningInput,
interval time.Duration,
metricC chan telegraf.Metric,
) {
defer panicRecover(input)
ticker := time.NewTicker(interval)
defer ticker.Stop()
for {
acc := NewAccumulator(input, metricC)
acc.SetPrecision(a.Config.Agent.Precision.Duration,
a.Config.Agent.Interval.Duration)
input.SetDebug(a.Config.Agent.Debug)
input.SetDefaultTags(a.Config.Tags)
internal.RandomSleep(a.Config.Agent.CollectionJitter.Duration, shutdown)
start := time.Now()
gatherWithTimeout(shutdown, input, acc, interval)
elapsed := time.Since(start)
log.Printf("D! Input [%s] gathered metrics, (%s interval) in %s\n",
input.Name(), interval, elapsed)
select {
case <-shutdown:
return
case <-ticker.C:
continue
}
}
}
// gatherWithTimeout gathers from the given input, with the given timeout.
// when the given timeout is reached, gatherWithTimeout logs an error message
// but continues waiting for it to return. This is to avoid leaving behind
// hung processes, and to prevent re-calling the same hung process over and
// over.
func gatherWithTimeout(
shutdown chan struct{},
input *models.RunningInput,
acc *accumulator,
timeout time.Duration,
) {
ticker := time.NewTicker(timeout)
defer ticker.Stop()
done := make(chan error)
go func() {
done <- input.Input.Gather(acc)
}()
for {
select {
case err := <-done:
if err != nil {
log.Printf("E! ERROR in input [%s]: %s", input.Name(), err)
}
return
case <-ticker.C:
log.Printf("E! ERROR: input [%s] took longer to collect than "+
"collection interval (%s)",
input.Name(), timeout)
continue
case <-shutdown:
return
}
}
}
// Test verifies that we can 'Gather' from all inputs with their configured
// Config struct
func (a *Agent) Test() error {
shutdown := make(chan struct{})
defer close(shutdown)
metricC := make(chan telegraf.Metric)
// dummy receiver for the point channel
go func() {
for {
select {
case <-metricC:
// do nothing
case <-shutdown:
return
}
}
}()
for _, input := range a.Config.Inputs {
acc := NewAccumulator(input, metricC)
acc.SetPrecision(a.Config.Agent.Precision.Duration,
a.Config.Agent.Interval.Duration)
input.SetTrace(true)
input.SetDefaultTags(a.Config.Tags)
fmt.Printf("* Plugin: %s, Collection 1\n", input.Name())
if input.Config.Interval != 0 {
fmt.Printf("* Internal: %s\n", input.Config.Interval)
}
if err := input.Input.Gather(acc); err != nil {
return err
}
if acc.errCount > 0 {
return fmt.Errorf("Errors encountered during processing")
}
// Special instructions for some inputs. cpu, for example, needs to be
// run twice in order to return cpu usage percentages.
switch input.Name() {
case "cpu", "mongodb", "procstat":
time.Sleep(500 * time.Millisecond)
fmt.Printf("* Plugin: %s, Collection 2\n", input.Name())
if err := input.Input.Gather(acc); err != nil {
return err
}
}
}
return nil
}
// flush writes a list of metrics to all configured outputs
func (a *Agent) flush() {
var wg sync.WaitGroup
wg.Add(len(a.Config.Outputs))
for _, o := range a.Config.Outputs {
go func(output *models.RunningOutput) {
defer wg.Done()
err := output.Write()
if err != nil {
log.Printf("E! Error writing to output [%s]: %s\n",
output.Name, err.Error())
}
}(o)
}
wg.Wait()
}
// flusher monitors the metrics input channel and flushes on the minimum interval
func (a *Agent) flusher(shutdown chan struct{}, metricC chan telegraf.Metric) error {
// Inelegant, but this sleep is to allow the Gather threads to run, so that
// the flusher will flush after metrics are collected.
time.Sleep(time.Millisecond * 300)
// create an output metric channel and a gorouting that continously passes
// each metric onto the output plugins & aggregators.
outMetricC := make(chan telegraf.Metric, 100)
var wg sync.WaitGroup
wg.Add(1)
go func() {
defer wg.Done()
for {
select {
case <-shutdown:
if len(outMetricC) > 0 {
// keep going until outMetricC is flushed
continue
}
return
case m := <-outMetricC:
// if dropOriginal is set to true, then we will only send this
// metric to the aggregators, not the outputs.
var dropOriginal bool
if !m.IsAggregate() {
for _, agg := range a.Config.Aggregators {
if ok := agg.Add(copyMetric(m)); ok {
dropOriginal = true
}
}
}
if !dropOriginal {
for i, o := range a.Config.Outputs {
if i == len(a.Config.Outputs)-1 {
o.AddMetric(m)
} else {
o.AddMetric(copyMetric(m))
}
}
}
}
}
}()
ticker := time.NewTicker(a.Config.Agent.FlushInterval.Duration)
for {
select {
case <-shutdown:
log.Println("I! Hang on, flushing any cached metrics before shutdown")
// wait for outMetricC to get flushed before flushing outputs
wg.Wait()
a.flush()
return nil
case <-ticker.C:
internal.RandomSleep(a.Config.Agent.FlushJitter.Duration, shutdown)
a.flush()
case metric := <-metricC:
// NOTE potential bottleneck here as we put each metric through the
// processors serially.
mS := []telegraf.Metric{metric}
for _, processor := range a.Config.Processors {
mS = processor.Apply(mS...)
}
for _, m := range mS {
outMetricC <- m
}
}
}
}
// Run runs the agent daemon, gathering every Interval
func (a *Agent) Run(shutdown chan struct{}) error {
var wg sync.WaitGroup
log.Printf("I! Agent Config: Interval:%s, Quiet:%#v, Hostname:%#v, "+
"Flush Interval:%s \n",
a.Config.Agent.Interval.Duration, a.Config.Agent.Quiet,
a.Config.Agent.Hostname, a.Config.Agent.FlushInterval.Duration)
// channel shared between all input threads for accumulating metrics
metricC := make(chan telegraf.Metric, 100)
// Start all ServicePlugins
for _, input := range a.Config.Inputs {
switch p := input.Input.(type) {
case telegraf.ServiceInput:
acc := NewAccumulator(input, metricC)
// Service input plugins should set their own precision of their
// metrics.
acc.SetPrecision(time.Nanosecond, 0)
input.SetDefaultTags(a.Config.Tags)
if err := p.Start(acc); err != nil {
log.Printf("E! Service for input %s failed to start, exiting\n%s\n",
input.Name(), err.Error())
return err
}
defer p.Stop()
}
}
// Round collection to nearest interval by sleeping
if a.Config.Agent.RoundInterval {
i := int64(a.Config.Agent.Interval.Duration)
time.Sleep(time.Duration(i - (time.Now().UnixNano() % i)))
}
wg.Add(1)
go func() {
defer wg.Done()
if err := a.flusher(shutdown, metricC); err != nil {
log.Printf("E! Flusher routine failed, exiting: %s\n", err.Error())
close(shutdown)
}
}()
wg.Add(len(a.Config.Aggregators))
for _, aggregator := range a.Config.Aggregators {
go func(agg *models.RunningAggregator) {
defer wg.Done()
acc := NewAccumulator(agg, metricC)
acc.SetPrecision(a.Config.Agent.Precision.Duration,
a.Config.Agent.Interval.Duration)
agg.Run(acc, shutdown)
}(aggregator)
}
wg.Add(len(a.Config.Inputs))
for _, input := range a.Config.Inputs {
interval := a.Config.Agent.Interval.Duration
// overwrite global interval if this plugin has it's own.
if input.Config.Interval != 0 {
interval = input.Config.Interval
}
go func(in *models.RunningInput, interv time.Duration) {
defer wg.Done()
a.gatherer(shutdown, in, interv, metricC)
}(input, interval)
}
wg.Wait()
return nil
}
func copyMetric(m telegraf.Metric) telegraf.Metric {
t := time.Time(m.Time())
tags := make(map[string]string)
fields := make(map[string]interface{})
for k, v := range m.Tags() {
tags[k] = v
}
for k, v := range m.Fields() {
fields[k] = v
}
out, _ := telegraf.NewMetric(m.Name(), tags, fields, t)
return out
}