forked from imjerrybao/apex
/
log.go
94 lines (77 loc) · 1.94 KB
/
log.go
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package logs
import (
"fmt"
"time"
"github.com/apex/log"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
)
// Log implements log fetching and polling for CloudWatchLogs,
// and represents a single group.
type Log struct {
Config
GroupName string
Log log.Interface
err error
}
// Start consuming logs.
func (l *Log) Start() <-chan *Event {
ch := make(chan *Event)
go l.start(ch)
return ch
}
// start consuming and exit after pagination if Follow is not enabled.
func (l *Log) start(ch chan<- *Event) {
defer close(ch)
l.Log.Debug("enter")
defer l.Log.Debug("exit")
var start = l.StartTime.UnixNano() / int64(time.Millisecond)
var nextToken *string
var err error
for {
l.Log.WithField("start", start).Debug("request")
nextToken, start, err = l.fetch(nextToken, start, ch)
if err != nil {
l.err = fmt.Errorf("log %q: %s", l.GroupName, err)
break
}
if nextToken == nil && l.Follow {
time.Sleep(l.PollInterval)
l.Log.WithField("start", start).Debug("poll")
continue
}
if nextToken == nil {
break
}
}
}
// fetch logs relative to the given token and start time. We ignore when the log group is not found.
func (l *Log) fetch(nextToken *string, start int64, ch chan<- *Event) (*string, int64, error) {
res, err := l.Service.FilterLogEvents(&cloudwatchlogs.FilterLogEventsInput{
LogGroupName: &l.GroupName,
FilterPattern: &l.FilterPattern,
StartTime: &start,
NextToken: nextToken,
})
if e, ok := err.(awserr.Error); ok {
if e.Code() == "ResourceNotFoundException" {
l.Log.Debug("not found")
return nil, 0, nil
}
}
if err != nil {
return nil, 0, err
}
for _, event := range res.Events {
start = *event.Timestamp + 1
ch <- &Event{
GroupName: l.GroupName,
Message: *event.Message,
}
}
return res.NextToken, start, nil
}
// Err returns the first error, if any, during processing.
func (l *Log) Err() error {
return l.err
}