/
awslogtail.go
300 lines (242 loc) · 6.02 KB
/
awslogtail.go
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package main
import (
"errors"
"fmt"
"os"
"sort"
"strings"
"time"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
"github.com/aws/aws-sdk-go/service/ec2"
)
const (
logEventLimit = 100
pollInterval = time.Second * 5
)
type stream struct {
name string
live bool
}
func findEC2Instances(sess *session.Session, filter []string, output chan<- stream) (err error) {
instances, err := ec2.New(sess).DescribeInstances(&ec2.DescribeInstancesInput{
MaxResults: aws.Int64(1000),
})
if err != nil {
return
}
go func() {
defer close(output)
for _, r := range instances.Reservations {
for _, i := range r.Instances {
if len(filter) > 0 {
var name string
for _, t := range i.Tags {
if *t.Key == "Name" {
name = *t.Value
break
}
}
var match bool
for _, s := range filter {
if strings.HasPrefix(name, s) {
match = true
break
}
}
if !match {
continue
}
}
output <- stream{
name: *i.InstanceId,
live: *i.State.Code != 48,
}
}
}
}()
return
}
func findLogStreamsSince(logService *cloudwatchlogs.CloudWatchLogs, logGroup string, startTime, endTime time.Time, output chan<- stream) {
var (
startTimestamp = startTime.UnixNano() / 1000000
endTimestamp = endTime.UnixNano() / 1000000
)
go func() {
defer close(output)
var nextToken *string
for {
logStreams, err := logService.DescribeLogStreams(&cloudwatchlogs.DescribeLogStreamsInput{
Descending: aws.Bool(true),
LogGroupName: &logGroup,
NextToken: nextToken,
OrderBy: aws.String("LastEventTime"),
})
if err != nil {
panic(err)
}
for _, logStream := range logStreams.LogStreams {
fmt.Fprintf(os.Stderr, "%s...%s %s\n", time.Unix(0, *logStream.FirstEventTimestamp*1000000), time.Unix(0, *logStream.LastEventTimestamp*1000000), *logStream.LogStreamName)
if endTimestamp > 0 && *logStream.FirstEventTimestamp > endTimestamp {
continue
}
if *logStream.LastEventTimestamp < startTimestamp {
return
}
output <- stream{
name: *logStream.LogStreamName,
}
}
nextToken = logStreams.NextToken
}
}()
return
}
func Run(sess *session.Session, logGroup string, filter []string, doFollow bool, limit int, startTime, endTime time.Time) (err error) {
logService := cloudwatchlogs.New(sess)
var (
streams = make(chan stream, 10)
initial = make(chan string, 100)
follow chan string
count int
)
if doFollow {
follow = make(chan string, 100)
}
if startTime.IsZero() {
if err = findEC2Instances(sess, filter, streams); err != nil {
return
}
} else {
findLogStreamsSince(logService, logGroup, startTime, endTime, streams)
}
for s := range streams {
go load(logService, initial, follow, logGroup, limit, startTime, endTime, s.name, !s.live)
count++
}
if count == 0 {
err = errors.New("No instances")
return
}
var lines []string
for line := range initial {
if line != "" {
lines = append(lines, line)
} else {
count--
if count == 0 {
break
}
}
}
sort.Stable(byTimestamp(lines))
if endTime.IsZero() && len(lines) > limit {
if startTime.IsZero() {
lines = lines[len(lines)-limit:]
} else {
lines = lines[:limit]
}
}
for _, line := range lines {
fmt.Println(line)
}
if follow != nil {
for line := range follow {
fmt.Println(line)
}
}
return
}
func load(logService *cloudwatchlogs.CloudWatchLogs, initial chan<- string, follow chan<- string, logGroup string, limit int, startTime, endTime time.Time, instanceId string, terminated bool) {
initialParams := &cloudwatchlogs.GetLogEventsInput{
LogGroupName: &logGroup,
LogStreamName: &instanceId,
}
if endTime.IsZero() {
if !startTime.IsZero() {
initialParams.StartFromHead = aws.Bool(true)
initialParams.StartTime = aws.Int64(startTime.UnixNano() / int64(time.Millisecond))
} else {
initialParams.EndTime = aws.Int64(time.Now().UnixNano() / int64(time.Millisecond))
}
initialParams.Limit = aws.Int64(int64(limit))
} else {
initialParams.StartFromHead = aws.Bool(true)
initialParams.StartTime = aws.Int64(startTime.UnixNano() / int64(time.Millisecond))
initialParams.EndTime = aws.Int64(endTime.UnixNano() / int64(time.Millisecond))
}
var token *string
shouldContinue := func(p *cloudwatchlogs.GetLogEventsOutput, lastPage bool) bool {
var end bool
if len(p.Events) == 0 {
end = true
}
for _, e := range p.Events {
if *e.Message == "" {
end = true
} else {
t, m := formatMessage(e)
if endTime.IsZero() || t.Before(endTime) {
initial <- m
} else {
end = true
}
}
}
token = p.NextForwardToken
if !startTime.IsZero() && !endTime.IsZero() {
return !end
} else {
return false
}
}
err := logService.GetLogEventsPages(initialParams, shouldContinue)
initial <- ""
if err != nil {
fmt.Fprintf(os.Stderr, "%s: %v\n", instanceId, err)
return
}
if follow == nil || terminated {
return
}
for {
logEvents, err := logService.GetLogEvents(&cloudwatchlogs.GetLogEventsInput{
LogGroupName: &logGroup,
LogStreamName: &instanceId,
NextToken: token,
StartFromHead: aws.Bool(true),
})
if err != nil {
fmt.Fprintf(os.Stderr, "%s: %v\n", instanceId, err)
continue
}
for _, e := range logEvents.Events {
_, m := formatMessage(e)
follow <- m
}
token = logEvents.NextForwardToken
time.Sleep(pollInterval)
}
}
func formatMessage(e *cloudwatchlogs.OutputLogEvent) (t time.Time, m string) {
m = *e.Message
if len(m) > 16 {
if _, err := time.Parse("Jan 2 15:04:05 ", m[:16]); err == nil {
m = m[16:]
}
}
t = time.Unix(0, *e.Timestamp*1000000)
m = t.Format("2006-01-02 15:04:05 ") + m
return
}
type byTimestamp []string
func (messages byTimestamp) Len() int {
return len(messages)
}
func (messages byTimestamp) Swap(i, j int) {
messages[i], messages[j] = messages[j], messages[i]
}
func (messages byTimestamp) Less(i, j int) bool {
return messages[i][:19] < messages[j][:19]
}