/
main.go
248 lines (227 loc) · 5.73 KB
/
main.go
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package main
import (
"bytes"
"flag"
"fmt"
"io/ioutil"
"os"
"os/signal"
"sync"
"syscall"
"text/template"
"time"
log "github.com/Sirupsen/logrus"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/ec2metadata"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
)
var version string
var wg = &sync.WaitGroup{}
var cwlogs *cloudwatchlogs.CloudWatchLogs
var ec2meta *ec2metadata.EC2Metadata
const defaultConfigFile = "/etc/logs_agent.cfg"
func init() {
debug()
}
func usage() {
fmt.Fprintf(os.Stdout, "Usage of %s (version %s):\n", os.Args[0], version)
flag.PrintDefaults()
}
func main() {
flag.Usage = usage
cfgfile := flag.String("c", defaultConfigFile, "Config file location.")
flag.Parse()
log.SetFormatter(&programFormat{})
log.SetOutput(os.Stderr)
log.SetLevel(log.ErrorLevel)
config := NewIniConfig(*cfgfile)
if err := config.Validate(); err != nil {
log.Fatal(err)
}
settings := config.GetMain()
flows := config.GetFlows()
setServices()
log.SetOutput(ioutil.Discard)
hook := pickHook(strToOutput[settings.LogOutput])
log.AddHook(hook)
log.SetLevel(strToLevel[settings.LogLevel])
receivers := setupFlows(flows)
signals := make(chan os.Signal, 1)
signal.Notify(signals, os.Interrupt, syscall.SIGTERM)
select {
case <-signals:
log.Infof("got SIGINT/SIGTERM")
break
}
closeAll(receivers)
log.Debugf("waiting for upload to finish")
wg.Wait()
}
func setServices() {
sess, err := session.NewSessionWithOptions(session.Options{
SharedConfigState: session.SharedConfigEnable,
})
if err != nil {
log.Fatal(err)
}
cwlogs = cloudwatchlogs.New(sess)
ec2meta = ec2metadata.New(sess)
}
func closeAll(receivers []receiver) {
log.Info("closing connections")
for _, receiver := range receivers {
receiver.Close()
}
}
func setupFlows(flows []*FlowCfg) (receivers []receiver) {
log.Debug("seting flow")
for _, flow := range flows {
receiver := newReceiver(flow.Source)
receivers = append(receivers, receiver)
if err := receiver.Listen(); err != nil {
closeAll(receivers)
log.Fatal(err)
}
in := receiver.Receive()
out := make(chan logEvent)
format, _ := template.New("").Parse(flow.CloudwatchFormat)
go convertEvents(in, out, parserFunctions[flow.SyslogFormat], format)
wg.Add(1)
go recToDst(out, flow)
}
return
}
// Parse, filter incoming messages and send them to destination.
func convertEvents(in <-chan string, out chan<- logEvent, parsefn syslogParser, tpl *template.Template) {
defer close(out)
buf := bytes.NewBuffer([]byte{})
for msg := range in {
parsed, err := parsefn(msg)
if err != nil {
continue
}
err = parsed.render(tpl, buf)
if err != nil {
continue
}
// Timestamp must be in milliseconds
event := logEvent{
msg: buf.String(),
timestamp: parsed.timestamp.Unix() * 1000,
}
err = event.validate()
if err != nil {
continue
}
out <- event
}
}
// Buffer received events and send them to cloudwatch.
func recToDst(in <-chan logEvent, cfg *FlowCfg) {
defer wg.Done()
stream_vars := getStreamVars()
stream_name := stream_vars.render(cfg.Stream)
dst := newDestination(stream_name, cfg.Group)
ticker := newDelayTicker(cfg.UploadDelay, dst)
defer ticker.Stop()
queue := &eventQueue{max_size: cfg.QueueSize}
var uploadDone chan batchFunc
var batch eventsList
for {
select {
case event, opened := <-in:
if !opened {
in = nil
break
}
queue.add(event)
case fn := <-uploadDone:
fn(batch, queue)
uploadDone = nil
case <-ticker.C:
log.Debugf("%s tick", dst)
if !queue.empty() && uploadDone == nil {
uploadDone, batch = upload(dst, queue)
}
}
if in == nil && queue.empty() {
break
}
}
}
func newDelayTicker(delay upload_delay, dst *destination) *time.Ticker {
d := time.Duration(delay) * time.Millisecond
log.Debugf("%s timer set to %s", dst, d)
return time.NewTicker(d)
}
/*
Sequence token must change in order to send next messages,
otherwise DataAlreadyAcceptedException is returned.
Only one upload can proceed / tick / stream.
*/
func upload(dst *destination, queue *eventQueue) (out chan batchFunc, batch eventsList) {
batch = queue.getBatch()
out = make(chan batchFunc)
log.Debugf("%s sending %d messages", dst, len(batch))
go func() {
result := dst.upload(batch)
out <- handleResult(dst, result)
}()
return out, batch
}
func handleResult(dst *destination, result error) batchFunc {
switch err := result.(type) {
case awserr.Error:
switch err.Code() {
case "InvalidSequenceTokenException":
log.Debugf("%s invalid sequence token", dst)
dst.setToken()
return addBack
case "ResourceNotFoundException":
log.Debugf("%s missing group/stream", dst)
dst.create()
dst.token = nil
return addBack
default:
log.Errorf("upload to %s failed %s %s", dst, err.Code(), err.Message())
}
case nil:
default:
log.Errorf("upload to %s failed %s ", dst, result)
}
return discard
}
type batchFunc func(batch eventsList, queue *eventQueue)
func addBack(batch eventsList, queue *eventQueue) {
queue.add(batch...)
}
func discard(batch eventsList, queue *eventQueue) {}
type streamVars struct {
InstanceID string
Hostname string
}
func (v streamVars) render(format string) string {
buf := bytes.NewBuffer([]byte{})
tpl, err := template.New("").Parse(format)
if err != nil {
log.Fatalf("failed to render stream name: %v", err)
}
tpl.Execute(buf, v)
return buf.String()
}
func getStreamVars() (variables streamVars) {
hostname, err := os.Hostname()
variables.Hostname = "UNKNOWN"
variables.InstanceID = "UNKNOWN"
if err == nil {
variables.Hostname = hostname
}
if ec2meta.Available() {
instance_document, err := ec2meta.GetInstanceIdentityDocument()
if err == nil {
variables.InstanceID = instance_document.InstanceID
}
}
return
}