/
promtail.go
216 lines (178 loc) · 4.52 KB
/
promtail.go
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package main
import (
"bufio"
"bytes"
"context"
"fmt"
"io"
"net/http"
"sort"
"strings"
"time"
"github.com/go-kit/log/level"
"github.com/gogo/protobuf/proto"
"github.com/golang/snappy"
"github.com/grafana/dskit/backoff"
"github.com/prometheus/common/model"
"github.com/grafana/loki/pkg/logproto"
)
const (
timeout = 5 * time.Second
minBackoff = 100 * time.Millisecond
maxBackoff = 30 * time.Second
maxRetries = 10
reservedLabelTenantID = "__tenant_id__"
userAgent = "lambda-promtail"
)
type entry struct {
labels model.LabelSet
entry logproto.Entry
}
type batch struct {
streams map[string]*logproto.Stream
size int
client Client
}
type batchIf interface {
add(ctx context.Context, e entry) error
encode() ([]byte, int, error)
createPushRequest() (*logproto.PushRequest, int)
flushBatch(ctx context.Context) error
}
func newBatch(ctx context.Context, pClient Client, entries ...entry) (*batch, error) {
b := &batch{
streams: map[string]*logproto.Stream{},
client: pClient,
}
for _, entry := range entries {
if err := b.add(ctx, entry); err != nil {
return nil, err
}
}
return b, nil
}
func (b *batch) add(ctx context.Context, e entry) error {
labels := labelsMapToString(e.labels, reservedLabelTenantID)
stream, ok := b.streams[labels]
if !ok {
b.streams[labels] = &logproto.Stream{
Labels: labels,
Entries: []logproto.Entry{},
}
stream = b.streams[labels]
}
stream.Entries = append(stream.Entries, e.entry)
b.size += len(e.entry.Line)
if b.size > batchSize {
return b.flushBatch(ctx)
}
return nil
}
func labelsMapToString(ls model.LabelSet, without ...model.LabelName) string {
lstrs := make([]string, 0, len(ls))
Outer:
for l, v := range ls {
for _, w := range without {
if l == w {
continue Outer
}
}
lstrs = append(lstrs, fmt.Sprintf("%s=%q", l, v))
}
sort.Strings(lstrs)
return fmt.Sprintf("{%s}", strings.Join(lstrs, ", "))
}
func (b *batch) encode() ([]byte, int, error) {
req, entriesCount := b.createPushRequest()
buf, err := proto.Marshal(req)
if err != nil {
return nil, 0, err
}
buf = snappy.Encode(nil, buf)
return buf, entriesCount, nil
}
func (b *batch) createPushRequest() (*logproto.PushRequest, int) {
req := logproto.PushRequest{
Streams: make([]logproto.Stream, 0, len(b.streams)),
}
entriesCount := 0
for _, stream := range b.streams {
req.Streams = append(req.Streams, *stream)
entriesCount += len(stream.Entries)
}
return &req, entriesCount
}
func (b *batch) flushBatch(ctx context.Context) error {
if b.client != nil {
err := b.client.sendToPromtail(ctx, b)
if err != nil {
return err
}
}
b.resetBatch()
return nil
}
func (b *batch) resetBatch() {
b.streams = make(map[string]*logproto.Stream)
b.size = 0
}
func (c *promtailClient) sendToPromtail(ctx context.Context, b *batch) error {
buf, _, err := b.encode()
if err != nil {
return err
}
backoff := backoff.New(ctx, *c.config.backoff)
var status int
for {
// send uses `timeout` internally, so `context.Background` is good enough.
status, err = c.send(context.Background(), buf)
// Only retry 429s, 500s and connection-level errors.
if status > 0 && status != 429 && status/100 != 5 {
break
}
level.Error(*c.log).Log("err", fmt.Errorf("error sending batch, will retry, status: %d error: %s\n", status, err))
backoff.Wait()
// Make sure it sends at least once before checking for retry.
if !backoff.Ongoing() {
break
}
}
if err != nil {
level.Error(*c.log).Log("err", fmt.Errorf("Failed to send logs! %s\n", err))
return err
}
return nil
}
func (c *promtailClient) send(ctx context.Context, buf []byte) (int, error) {
ctx, cancel := context.WithTimeout(ctx, c.config.http.timeout)
defer cancel()
req, err := http.NewRequest("POST", writeAddress.String(), bytes.NewReader(buf))
if err != nil {
return -1, err
}
req.Header.Set("Content-Type", contentType)
req.Header.Set("User-Agent", userAgent)
if tenantID != "" {
req.Header.Set("X-Scope-OrgID", tenantID)
}
if username != "" && password != "" {
req.SetBasicAuth(username, password)
}
if bearerToken != "" {
req.Header.Set("Authorization", "Bearer "+bearerToken)
}
resp, err := c.http.Do(req.WithContext(ctx))
if err != nil {
return -1, err
}
defer resp.Body.Close()
if resp.StatusCode/100 != 2 {
scanner := bufio.NewScanner(io.LimitReader(resp.Body, maxErrMsgLen))
line := ""
if scanner.Scan() {
line = scanner.Text()
}
err = fmt.Errorf("server returned HTTP status %s (%d): %s", resp.Status, resp.StatusCode, line)
}
return resp.StatusCode, err
}