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client.go
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client.go
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package client
import (
"bufio"
"bytes"
"context"
"crypto/sha256"
"errors"
"fmt"
"io"
"net/http"
"strconv"
"sync"
"time"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/grafana/dskit/backoff"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/config"
"github.com/prometheus/common/model"
"github.com/grafana/loki/v3/clients/pkg/promtail/api"
lokiutil "github.com/grafana/loki/v3/pkg/util"
"github.com/grafana/loki/v3/pkg/util/build"
)
const (
contentType = "application/x-protobuf"
maxErrMsgLen = 1024
// Label reserved to override the tenant ID while processing
// pipeline stages
ReservedLabelTenantID = "__tenant_id__"
LatencyLabel = "filename"
HostLabel = "host"
ClientLabel = "client"
TenantLabel = "tenant"
ReasonLabel = "reason"
ReasonGeneric = "ingester_error"
ReasonRateLimited = "rate_limited"
ReasonStreamLimited = "stream_limited"
ReasonLineTooLong = "line_too_long"
)
var Reasons = []string{ReasonGeneric, ReasonRateLimited, ReasonStreamLimited, ReasonLineTooLong}
var UserAgent = fmt.Sprintf("promtail/%s", build.Version)
type Metrics struct {
encodedBytes *prometheus.CounterVec
sentBytes *prometheus.CounterVec
droppedBytes *prometheus.CounterVec
sentEntries *prometheus.CounterVec
droppedEntries *prometheus.CounterVec
mutatedEntries *prometheus.CounterVec
mutatedBytes *prometheus.CounterVec
requestDuration *prometheus.HistogramVec
batchRetries *prometheus.CounterVec
countersWithHost []*prometheus.CounterVec
countersWithHostTenant []*prometheus.CounterVec
countersWithHostTenantReason []*prometheus.CounterVec
}
func NewMetrics(reg prometheus.Registerer) *Metrics {
var m Metrics
m.encodedBytes = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "encoded_bytes_total",
Help: "Number of bytes encoded and ready to send.",
}, []string{HostLabel})
m.sentBytes = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "sent_bytes_total",
Help: "Number of bytes sent.",
}, []string{HostLabel})
m.droppedBytes = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "dropped_bytes_total",
Help: "Number of bytes dropped because failed to be sent to the ingester after all retries.",
}, []string{HostLabel, TenantLabel, ReasonLabel})
m.sentEntries = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "sent_entries_total",
Help: "Number of log entries sent to the ingester.",
}, []string{HostLabel})
m.droppedEntries = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "dropped_entries_total",
Help: "Number of log entries dropped because failed to be sent to the ingester after all retries.",
}, []string{HostLabel, TenantLabel, ReasonLabel})
m.mutatedEntries = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "mutated_entries_total",
Help: "The total number of log entries that have been mutated.",
}, []string{HostLabel, TenantLabel, ReasonLabel})
m.mutatedBytes = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "mutated_bytes_total",
Help: "The total number of bytes that have been mutated.",
}, []string{HostLabel, TenantLabel, ReasonLabel})
m.requestDuration = prometheus.NewHistogramVec(prometheus.HistogramOpts{
Namespace: "promtail",
Name: "request_duration_seconds",
Help: "Duration of send requests.",
}, []string{"status_code", HostLabel})
m.batchRetries = prometheus.NewCounterVec(prometheus.CounterOpts{
Namespace: "promtail",
Name: "batch_retries_total",
Help: "Number of times batches has had to be retried.",
}, []string{HostLabel, TenantLabel})
m.countersWithHost = []*prometheus.CounterVec{
m.encodedBytes, m.sentBytes, m.sentEntries,
}
m.countersWithHostTenant = []*prometheus.CounterVec{
m.batchRetries,
}
m.countersWithHostTenantReason = []*prometheus.CounterVec{
m.droppedBytes, m.droppedEntries, m.mutatedEntries, m.mutatedBytes,
}
if reg != nil {
m.encodedBytes = mustRegisterOrGet(reg, m.encodedBytes).(*prometheus.CounterVec)
m.sentBytes = mustRegisterOrGet(reg, m.sentBytes).(*prometheus.CounterVec)
m.droppedBytes = mustRegisterOrGet(reg, m.droppedBytes).(*prometheus.CounterVec)
m.sentEntries = mustRegisterOrGet(reg, m.sentEntries).(*prometheus.CounterVec)
m.droppedEntries = mustRegisterOrGet(reg, m.droppedEntries).(*prometheus.CounterVec)
m.mutatedEntries = mustRegisterOrGet(reg, m.mutatedEntries).(*prometheus.CounterVec)
m.mutatedBytes = mustRegisterOrGet(reg, m.mutatedBytes).(*prometheus.CounterVec)
m.requestDuration = mustRegisterOrGet(reg, m.requestDuration).(*prometheus.HistogramVec)
m.batchRetries = mustRegisterOrGet(reg, m.batchRetries).(*prometheus.CounterVec)
}
return &m
}
func mustRegisterOrGet(reg prometheus.Registerer, c prometheus.Collector) prometheus.Collector {
if err := reg.Register(c); err != nil {
if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
return are.ExistingCollector
}
panic(err)
}
return c
}
// Client pushes entries to Loki and can be stopped
type Client interface {
api.EntryHandler
// Stop goroutine sending batch of entries without retries.
StopNow()
Name() string
}
// Client for pushing logs in snappy-compressed protos over HTTP.
type client struct {
name string
metrics *Metrics
logger log.Logger
cfg Config
client *http.Client
entries chan api.Entry
once sync.Once
wg sync.WaitGroup
externalLabels model.LabelSet
// ctx is used in any upstream calls from the `client`.
ctx context.Context
cancel context.CancelFunc
maxStreams int
maxLineSize int
maxLineSizeTruncate bool
}
// Tripperware can wrap a roundtripper.
type Tripperware func(http.RoundTripper) http.RoundTripper
// New makes a new Client.
func New(metrics *Metrics, cfg Config, maxStreams, maxLineSize int, maxLineSizeTruncate bool, logger log.Logger) (Client, error) {
return newClient(metrics, cfg, maxStreams, maxLineSize, maxLineSizeTruncate, logger)
}
func newClient(metrics *Metrics, cfg Config, maxStreams, maxLineSize int, maxLineSizeTruncate bool, logger log.Logger) (*client, error) {
if cfg.URL.URL == nil {
return nil, errors.New("client needs target URL")
}
if metrics == nil {
return nil, errors.New("metrics must be instantiated")
}
ctx, cancel := context.WithCancel(context.Background())
c := &client{
logger: log.With(logger, "component", "client", "host", cfg.URL.Host),
cfg: cfg,
entries: make(chan api.Entry),
metrics: metrics,
name: asSha256(cfg),
externalLabels: cfg.ExternalLabels.LabelSet,
ctx: ctx,
cancel: cancel,
maxStreams: maxStreams,
maxLineSize: maxLineSize,
maxLineSizeTruncate: maxLineSizeTruncate,
}
if cfg.Name != "" {
c.name = cfg.Name
}
err := cfg.Client.Validate()
if err != nil {
return nil, err
}
c.client, err = config.NewClientFromConfig(cfg.Client, "promtail", config.WithHTTP2Disabled())
if err != nil {
return nil, err
}
c.client.Timeout = cfg.Timeout
// Initialize counters to 0 so the metrics are exported before the first
// occurrence of incrementing to avoid missing metrics.
for _, counter := range c.metrics.countersWithHost {
counter.WithLabelValues(c.cfg.URL.Host).Add(0)
}
c.wg.Add(1)
go c.run()
return c, nil
}
// NewWithTripperware creates a new Loki client with a custom tripperware.
func NewWithTripperware(metrics *Metrics, cfg Config, maxStreams, maxLineSize int, maxLineSizeTruncate bool, logger log.Logger, tp Tripperware) (Client, error) {
c, err := newClient(metrics, cfg, maxStreams, maxLineSize, maxLineSizeTruncate, logger)
if err != nil {
return nil, err
}
if tp != nil {
c.client.Transport = tp(c.client.Transport)
}
return c, nil
}
func (c *client) initBatchMetrics(tenantID string) {
// Initialize counters to 0 so the metrics are exported before the first
// occurrence of incrementing to avoid missing metrics.
for _, counter := range c.metrics.countersWithHostTenantReason {
for _, reason := range Reasons {
counter.WithLabelValues(c.cfg.URL.Host, tenantID, reason).Add(0)
}
}
for _, counter := range c.metrics.countersWithHostTenant {
counter.WithLabelValues(c.cfg.URL.Host, tenantID).Add(0)
}
}
func (c *client) run() {
batches := map[string]*batch{}
// Given the client handles multiple batches (1 per tenant) and each batch
// can be created at a different point in time, we look for batches whose
// max wait time has been reached every 10 times per BatchWait, so that the
// maximum delay we have sending batches is 10% of the max waiting time.
// We apply a cap of 10ms to the ticker, to avoid too frequent checks in
// case the BatchWait is very low.
minWaitCheckFrequency := 10 * time.Millisecond
maxWaitCheckFrequency := c.cfg.BatchWait / 10
if maxWaitCheckFrequency < minWaitCheckFrequency {
maxWaitCheckFrequency = minWaitCheckFrequency
}
maxWaitCheck := time.NewTicker(maxWaitCheckFrequency)
defer func() {
maxWaitCheck.Stop()
// Send all pending batches
for tenantID, batch := range batches {
c.sendBatch(tenantID, batch)
}
c.wg.Done()
}()
for {
select {
case e, ok := <-c.entries:
if !ok {
return
}
e, tenantID := c.processEntry(e)
// Either drop or mutate the log entry because its length is greater than maxLineSize. maxLineSize == 0 means disabled.
if c.maxLineSize != 0 && len(e.Line) > c.maxLineSize {
if !c.maxLineSizeTruncate {
c.metrics.droppedEntries.WithLabelValues(c.cfg.URL.Host, tenantID, ReasonLineTooLong).Inc()
c.metrics.droppedBytes.WithLabelValues(c.cfg.URL.Host, tenantID, ReasonLineTooLong).Add(float64(len(e.Line)))
break
}
c.metrics.mutatedEntries.WithLabelValues(c.cfg.URL.Host, tenantID, ReasonLineTooLong).Inc()
c.metrics.mutatedBytes.WithLabelValues(c.cfg.URL.Host, tenantID, ReasonLineTooLong).Add(float64(len(e.Line) - c.maxLineSize))
e.Line = e.Line[:c.maxLineSize]
}
batch, ok := batches[tenantID]
// If the batch doesn't exist yet, we create a new one with the entry
if !ok {
batches[tenantID] = newBatch(c.maxStreams, e)
c.initBatchMetrics(tenantID)
break
}
// If adding the entry to the batch will increase the size over the max
// size allowed, we do send the current batch and then create a new one
if batch.sizeBytesAfter(e) > c.cfg.BatchSize {
c.sendBatch(tenantID, batch)
batches[tenantID] = newBatch(c.maxStreams, e)
break
}
// The max size of the batch isn't reached, so we can add the entry
err := batch.add(e)
if err != nil {
level.Error(c.logger).Log("msg", "batch add err", "tenant", tenantID, "error", err)
reason := ReasonGeneric
if err.Error() == errMaxStreamsLimitExceeded {
reason = ReasonStreamLimited
}
c.metrics.droppedBytes.WithLabelValues(c.cfg.URL.Host, tenantID, reason).Add(float64(len(e.Line)))
c.metrics.droppedEntries.WithLabelValues(c.cfg.URL.Host, tenantID, reason).Inc()
return
}
case <-maxWaitCheck.C:
// Send all batches whose max wait time has been reached
for tenantID, batch := range batches {
if batch.age() < c.cfg.BatchWait {
continue
}
c.sendBatch(tenantID, batch)
delete(batches, tenantID)
}
}
}
}
func (c *client) Chan() chan<- api.Entry {
return c.entries
}
func asSha256(o interface{}) string {
h := sha256.New()
h.Write([]byte(fmt.Sprintf("%v", o)))
temp := fmt.Sprintf("%x", h.Sum(nil))
return temp[:6]
}
func batchIsRateLimited(status int) bool {
return status == 429
}
func (c *client) sendBatch(tenantID string, batch *batch) {
buf, entriesCount, err := batch.encode()
if err != nil {
level.Error(c.logger).Log("msg", "error encoding batch", "error", err)
return
}
bufBytes := float64(len(buf))
c.metrics.encodedBytes.WithLabelValues(c.cfg.URL.Host).Add(bufBytes)
backoff := backoff.New(c.ctx, c.cfg.BackoffConfig)
var status int
for {
start := time.Now()
// send uses `timeout` internally, so `context.Background` is good enough.
status, err = c.send(context.Background(), tenantID, buf)
c.metrics.requestDuration.WithLabelValues(strconv.Itoa(status), c.cfg.URL.Host).Observe(time.Since(start).Seconds())
// Immediately drop rate limited batches to avoid HOL blocking for other tenants not experiencing throttling
if c.cfg.DropRateLimitedBatches && batchIsRateLimited(status) {
level.Warn(c.logger).Log("msg", "dropping batch due to rate limiting applied at ingester")
c.metrics.droppedBytes.WithLabelValues(c.cfg.URL.Host, tenantID, ReasonRateLimited).Add(bufBytes)
c.metrics.droppedEntries.WithLabelValues(c.cfg.URL.Host, tenantID, ReasonRateLimited).Add(float64(entriesCount))
return
}
if err == nil {
c.metrics.sentBytes.WithLabelValues(c.cfg.URL.Host).Add(bufBytes)
c.metrics.sentEntries.WithLabelValues(c.cfg.URL.Host).Add(float64(entriesCount))
return
}
// Only retry 429s, 500s and connection-level errors.
if status > 0 && !batchIsRateLimited(status) && status/100 != 5 {
break
}
level.Warn(c.logger).Log("msg", "error sending batch, will retry", "status", status, "tenant", tenantID, "error", err)
c.metrics.batchRetries.WithLabelValues(c.cfg.URL.Host, tenantID).Inc()
backoff.Wait()
// Make sure it sends at least once before checking for retry.
if !backoff.Ongoing() {
break
}
}
if err != nil {
level.Error(c.logger).Log("msg", "final error sending batch", "status", status, "tenant", tenantID, "error", err)
// If the reason for the last retry error was rate limiting, count the drops as such, even if the previous errors
// were for a different reason
dropReason := ReasonGeneric
if batchIsRateLimited(status) {
dropReason = ReasonRateLimited
}
c.metrics.droppedBytes.WithLabelValues(c.cfg.URL.Host, tenantID, dropReason).Add(bufBytes)
c.metrics.droppedEntries.WithLabelValues(c.cfg.URL.Host, tenantID, dropReason).Add(float64(entriesCount))
}
}
func (c *client) send(ctx context.Context, tenantID string, buf []byte) (int, error) {
ctx, cancel := context.WithTimeout(ctx, c.cfg.Timeout)
defer cancel()
req, err := http.NewRequestWithContext(ctx, "POST", c.cfg.URL.String(), bytes.NewReader(buf))
if err != nil {
return -1, err
}
req.Header.Set("Content-Type", contentType)
req.Header.Set("User-Agent", UserAgent)
// If the tenant ID is not empty promtail is running in multi-tenant mode, so
// we should send it to Loki
if tenantID != "" {
req.Header.Set("X-Scope-OrgID", tenantID)
}
// Add custom headers on request
if len(c.cfg.Headers) > 0 {
for k, v := range c.cfg.Headers {
if req.Header.Get(k) == "" {
req.Header.Add(k, v)
} else {
level.Warn(c.logger).Log("msg", "custom header key already exists, skipping", "key", k)
}
}
}
resp, err := c.client.Do(req)
if err != nil {
return -1, err
}
defer lokiutil.LogError("closing response body", 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
}
func (c *client) getTenantID(labels model.LabelSet) string {
// Check if it has been overridden while processing the pipeline stages
if value, ok := labels[ReservedLabelTenantID]; ok {
return string(value)
}
// Check if has been specified in the config
if c.cfg.TenantID != "" {
return c.cfg.TenantID
}
// Defaults to an empty string, which means the X-Scope-OrgID header
// will not be sent
return ""
}
// Stop the client.
func (c *client) Stop() {
c.once.Do(func() { close(c.entries) })
c.wg.Wait()
}
// StopNow stops the client without retries
func (c *client) StopNow() {
// cancel will stop retrying http requests.
c.cancel()
c.Stop()
}
func (c *client) processEntry(e api.Entry) (api.Entry, string) {
if len(c.externalLabels) > 0 {
e.Labels = c.externalLabels.Merge(e.Labels)
}
tenantID := c.getTenantID(e.Labels)
return e, tenantID
}
func (c *client) Name() string {
return c.name
}