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remotewrite.go
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remotewrite.go
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package remotewrite
import (
"bytes"
"context"
"flag"
"fmt"
"io"
"net/http"
"path"
"strings"
"sync"
"time"
"github.com/golang/snappy"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/promauth"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
"github.com/VictoriaMetrics/metrics"
)
var (
disablePathAppend = flag.Bool("remoteWrite.disablePathAppend", false, "Whether to disable automatic appending of '/api/v1/write' path to the configured -remoteWrite.url.")
sendTimeout = flag.Duration("remoteWrite.sendTimeout", 30*time.Second, "Timeout for sending data to the configured -remoteWrite.url.")
retryMinInterval = flag.Duration("remoteWrite.retryMinInterval", time.Second, "The minimum delay between retry attempts. Every next retry attempt will double the delay to prevent hammering of remote database. See also -remoteWrite.retryMaxInterval")
retryMaxTime = flag.Duration("remoteWrite.retryMaxTime", time.Second*30, "The max time spent on retry attempts for the failed remote-write request. Change this value if it is expected for remoteWrite.url to be unreachable for more than -remoteWrite.retryMaxTime. See also -remoteWrite.retryMinInterval")
)
// Client is an asynchronous HTTP client for writing
// timeseries via remote write protocol.
type Client struct {
addr string
c *http.Client
authCfg *promauth.Config
input chan prompbmarshal.TimeSeries
flushInterval time.Duration
maxBatchSize int
maxQueueSize int
wg sync.WaitGroup
doneCh chan struct{}
}
// Config is config for remote write.
type Config struct {
// Addr of remote storage
Addr string
AuthCfg *promauth.Config
// Concurrency defines number of readers that
// concurrently read from the queue and flush data
Concurrency int
// MaxBatchSize defines max number of timeseries
// to be flushed at once
MaxBatchSize int
// MaxQueueSize defines max length of input queue
// populated by Push method.
// Push will be rejected once queue is full.
MaxQueueSize int
// FlushInterval defines time interval for flushing batches
FlushInterval time.Duration
// Transport will be used by the underlying http.Client
Transport *http.Transport
}
const (
defaultConcurrency = 4
defaultMaxBatchSize = 1e3
defaultMaxQueueSize = 1e5
defaultFlushInterval = 5 * time.Second
defaultWriteTimeout = 30 * time.Second
)
// NewClient returns asynchronous client for
// writing timeseries via remotewrite protocol.
func NewClient(ctx context.Context, cfg Config) (*Client, error) {
if cfg.Addr == "" {
return nil, fmt.Errorf("config.Addr can't be empty")
}
if cfg.MaxBatchSize == 0 {
cfg.MaxBatchSize = defaultMaxBatchSize
}
if cfg.MaxQueueSize == 0 {
cfg.MaxQueueSize = defaultMaxQueueSize
}
if cfg.FlushInterval == 0 {
cfg.FlushInterval = defaultFlushInterval
}
if cfg.Transport == nil {
cfg.Transport = http.DefaultTransport.(*http.Transport).Clone()
}
cc := defaultConcurrency
if cfg.Concurrency > 0 {
cc = cfg.Concurrency
}
c := &Client{
c: &http.Client{
Timeout: *sendTimeout,
Transport: cfg.Transport,
},
addr: strings.TrimSuffix(cfg.Addr, "/"),
authCfg: cfg.AuthCfg,
flushInterval: cfg.FlushInterval,
maxBatchSize: cfg.MaxBatchSize,
maxQueueSize: cfg.MaxQueueSize,
doneCh: make(chan struct{}),
input: make(chan prompbmarshal.TimeSeries, cfg.MaxQueueSize),
}
for i := 0; i < cc; i++ {
c.run(ctx)
}
return c, nil
}
// Push adds timeseries into queue for writing into remote storage.
// Push returns and error if client is stopped or if queue is full.
func (c *Client) Push(s prompbmarshal.TimeSeries) error {
select {
case <-c.doneCh:
return fmt.Errorf("client is closed")
case c.input <- s:
return nil
default:
return fmt.Errorf("failed to push timeseries - queue is full (%d entries). "+
"Queue size is controlled by -remoteWrite.maxQueueSize flag",
c.maxQueueSize)
}
}
// Close stops the client and waits for all goroutines
// to exit.
func (c *Client) Close() error {
if c.doneCh == nil {
return fmt.Errorf("client is already closed")
}
close(c.input)
close(c.doneCh)
c.wg.Wait()
return nil
}
func (c *Client) run(ctx context.Context) {
ticker := time.NewTicker(c.flushInterval)
wr := &prompbmarshal.WriteRequest{}
shutdown := func() {
for ts := range c.input {
wr.Timeseries = append(wr.Timeseries, ts)
}
lastCtx, cancel := context.WithTimeout(context.Background(), defaultWriteTimeout)
logger.Infof("shutting down remote write client and flushing remained %d series", len(wr.Timeseries))
c.flush(lastCtx, wr)
cancel()
}
c.wg.Add(1)
go func() {
defer c.wg.Done()
defer ticker.Stop()
for {
select {
case <-c.doneCh:
shutdown()
return
case <-ctx.Done():
shutdown()
return
case <-ticker.C:
c.flush(ctx, wr)
case ts, ok := <-c.input:
if !ok {
continue
}
wr.Timeseries = append(wr.Timeseries, ts)
if len(wr.Timeseries) >= c.maxBatchSize {
c.flush(ctx, wr)
}
}
}
}()
}
var (
sentRows = metrics.NewCounter(`vmalert_remotewrite_sent_rows_total`)
sentBytes = metrics.NewCounter(`vmalert_remotewrite_sent_bytes_total`)
sendDuration = metrics.NewFloatCounter(`vmalert_remotewrite_send_duration_seconds_total`)
droppedRows = metrics.NewCounter(`vmalert_remotewrite_dropped_rows_total`)
droppedBytes = metrics.NewCounter(`vmalert_remotewrite_dropped_bytes_total`)
bufferFlushDuration = metrics.NewHistogram(`vmalert_remotewrite_flush_duration_seconds`)
_ = metrics.NewGauge(`vmalert_remotewrite_concurrency`, func() float64 {
return float64(*concurrency)
})
)
// flush is a blocking function that marshals WriteRequest and sends
// it to remote-write endpoint. Flush performs limited amount of retries
// if request fails.
func (c *Client) flush(ctx context.Context, wr *prompbmarshal.WriteRequest) {
if len(wr.Timeseries) < 1 {
return
}
defer prompbmarshal.ResetWriteRequest(wr)
defer bufferFlushDuration.UpdateDuration(time.Now())
data, err := wr.Marshal()
if err != nil {
logger.Errorf("failed to marshal WriteRequest: %s", err)
return
}
b := snappy.Encode(nil, data)
retryInterval, maxRetryInterval := *retryMinInterval, *retryMaxTime
if retryInterval > maxRetryInterval {
retryInterval = maxRetryInterval
}
timeStart := time.Now()
defer func() {
sendDuration.Add(time.Since(timeStart).Seconds())
}()
L:
for attempts := 0; ; attempts++ {
err := c.send(ctx, b)
if err == nil {
sentRows.Add(len(wr.Timeseries))
sentBytes.Add(len(b))
return
}
_, isNotRetriable := err.(*nonRetriableError)
logger.Warnf("attempt %d to send request failed: %s (retriable: %v)", attempts+1, err, !isNotRetriable)
if isNotRetriable {
// exit fast if error isn't retriable
break
}
// check if request has been cancelled before backoff
select {
case <-ctx.Done():
logger.Errorf("interrupting retry attempt %d: context cancelled", attempts+1)
break L
default:
}
timeLeftForRetries := maxRetryInterval - time.Since(timeStart)
if timeLeftForRetries < 0 {
// the max retry time has passed, so we give up
break
}
if retryInterval > timeLeftForRetries {
retryInterval = timeLeftForRetries
}
// sleeping to prevent remote db hammering
time.Sleep(retryInterval)
retryInterval *= 2
}
droppedRows.Add(len(wr.Timeseries))
droppedBytes.Add(len(b))
logger.Errorf("attempts to send remote-write request failed - dropping %d time series",
len(wr.Timeseries))
}
func (c *Client) send(ctx context.Context, data []byte) error {
r := bytes.NewReader(data)
req, err := http.NewRequest(http.MethodPost, c.addr, r)
if err != nil {
return fmt.Errorf("failed to create new HTTP request: %w", err)
}
// RFC standard compliant headers
req.Header.Set("Content-Encoding", "snappy")
req.Header.Set("Content-Type", "application/x-protobuf")
// Prometheus compliant headers
req.Header.Set("X-Prometheus-Remote-Write-Version", "0.1.0")
if c.authCfg != nil {
c.authCfg.SetHeaders(req, true)
}
if !*disablePathAppend {
req.URL.Path = path.Join(req.URL.Path, "/api/v1/write")
}
resp, err := c.c.Do(req.WithContext(ctx))
if err != nil {
return fmt.Errorf("error while sending request to %s: %w; Data len %d(%d)",
req.URL.Redacted(), err, len(data), r.Size())
}
defer func() { _ = resp.Body.Close() }()
body, _ := io.ReadAll(resp.Body)
// according to https://prometheus.io/docs/concepts/remote_write_spec/
// Prometheus remote Write compatible receivers MUST
switch resp.StatusCode / 100 {
case 2:
// respond with a HTTP 2xx status code when the write is successful.
return nil
case 4:
if resp.StatusCode != http.StatusTooManyRequests {
// MUST NOT retry write requests on HTTP 4xx responses other than 429
return &nonRetriableError{fmt.Errorf("unexpected response code %d for %s. Response body %q",
resp.StatusCode, req.URL.Redacted(), body)}
}
fallthrough
default:
return fmt.Errorf("unexpected response code %d for %s. Response body %q",
resp.StatusCode, req.URL.Redacted(), body)
}
}
type nonRetriableError struct {
err error
}
func (e *nonRetriableError) Error() string {
return e.err.Error()
}