forked from prometheus/prometheus
/
client.go
329 lines (287 loc) · 9.7 KB
/
client.go
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// Copyright 2016 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package remote
import (
"bufio"
"bytes"
"context"
"fmt"
"io"
"io/ioutil"
"net/http"
"strconv"
"strings"
"time"
"github.com/gogo/protobuf/proto"
"github.com/golang/snappy"
"github.com/opentracing-contrib/go-stdlib/nethttp"
"github.com/opentracing/opentracing-go"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
config_util "github.com/prometheus/common/config"
"github.com/prometheus/common/model"
"github.com/prometheus/common/version"
"github.com/rajvikram/prometheus/v2/prompb"
)
const maxErrMsgLen = 512
var UserAgent = fmt.Sprintf("Prometheus/%s", version.Version)
var (
remoteReadQueriesTotal = prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "read_queries_total",
Help: "The total number of remote read queries.",
},
[]string{remoteName, endpoint, "code"},
)
remoteReadQueries = prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "remote_read_queries",
Help: "The number of in-flight remote read queries.",
},
[]string{remoteName, endpoint},
)
remoteReadQueryDuration = prometheus.NewHistogramVec(
prometheus.HistogramOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "read_request_duration_seconds",
Help: "Histogram of the latency for remote read requests.",
Buckets: append(prometheus.DefBuckets, 25, 60),
},
[]string{remoteName, endpoint},
)
)
func init() {
prometheus.MustRegister(remoteReadQueriesTotal, remoteReadQueries, remoteReadQueryDuration)
}
// Client allows reading and writing from/to a remote HTTP endpoint.
type Client struct {
remoteName string // Used to differentiate clients in metrics.
url *config_util.URL
Client *http.Client
timeout time.Duration
headers map[string]string
retryOnRateLimit bool
readQueries prometheus.Gauge
readQueriesTotal *prometheus.CounterVec
readQueriesDuration prometheus.Observer
}
// ClientConfig configures a client.
type ClientConfig struct {
URL *config_util.URL
Timeout model.Duration
HTTPClientConfig config_util.HTTPClientConfig
Headers map[string]string
RetryOnRateLimit bool
}
// ReadClient uses the SAMPLES method of remote read to read series samples from remote server.
// TODO(bwplotka): Add streamed chunked remote read method as well (https://github.com/rajvikram/prometheus/v2/issues/5926).
type ReadClient interface {
Read(ctx context.Context, query *prompb.Query) (*prompb.QueryResult, error)
}
// NewReadClient creates a new client for remote read.
func NewReadClient(name string, conf *ClientConfig) (ReadClient, error) {
httpClient, err := config_util.NewClientFromConfig(conf.HTTPClientConfig, "remote_storage_read_client", false, false)
if err != nil {
return nil, err
}
t := httpClient.Transport
httpClient.Transport = &nethttp.Transport{
RoundTripper: t,
}
return &Client{
remoteName: name,
url: conf.URL,
Client: httpClient,
timeout: time.Duration(conf.Timeout),
readQueries: remoteReadQueries.WithLabelValues(name, conf.URL.String()),
readQueriesTotal: remoteReadQueriesTotal.MustCurryWith(prometheus.Labels{remoteName: name, endpoint: conf.URL.String()}),
readQueriesDuration: remoteReadQueryDuration.WithLabelValues(name, conf.URL.String()),
}, nil
}
// NewWriteClient creates a new client for remote write.
func NewWriteClient(name string, conf *ClientConfig) (WriteClient, error) {
httpClient, err := config_util.NewClientFromConfig(conf.HTTPClientConfig, "remote_storage_write_client", false, false)
if err != nil {
return nil, err
}
t := httpClient.Transport
httpClient.Transport = &nethttp.Transport{
RoundTripper: t,
}
return &Client{
remoteName: name,
url: conf.URL,
Client: httpClient,
retryOnRateLimit: conf.RetryOnRateLimit,
timeout: time.Duration(conf.Timeout),
headers: conf.Headers,
}, nil
}
const defaultBackoff = 0
type RecoverableError struct {
error
retryAfter model.Duration
}
// Store sends a batch of samples to the HTTP endpoint, the request is the proto marshalled
// and encoded bytes from codec.go.
func (c *Client) Store(ctx context.Context, req []byte) error {
httpReq, err := http.NewRequest("POST", c.url.String(), bytes.NewReader(req))
if err != nil {
// Errors from NewRequest are from unparsable URLs, so are not
// recoverable.
return err
}
for k, v := range c.headers {
httpReq.Header.Set(k, v)
}
httpReq.Header.Add("Content-Encoding", "snappy")
httpReq.Header.Set("Content-Type", "application/x-protobuf")
httpReq.Header.Set("User-Agent", UserAgent)
httpReq.Header.Set("X-Prometheus-Remote-Write-Version", "0.1.0")
ctx, cancel := context.WithTimeout(ctx, c.timeout)
defer cancel()
httpReq = httpReq.WithContext(ctx)
if parentSpan := opentracing.SpanFromContext(ctx); parentSpan != nil {
var ht *nethttp.Tracer
httpReq, ht = nethttp.TraceRequest(
parentSpan.Tracer(),
httpReq,
nethttp.OperationName("Remote Store"),
nethttp.ClientTrace(false),
)
defer ht.Finish()
}
httpResp, err := c.Client.Do(httpReq)
if err != nil {
// Errors from Client.Do are from (for example) network errors, so are
// recoverable.
return RecoverableError{err, defaultBackoff}
}
defer func() {
io.Copy(ioutil.Discard, httpResp.Body)
httpResp.Body.Close()
}()
if httpResp.StatusCode/100 != 2 {
scanner := bufio.NewScanner(io.LimitReader(httpResp.Body, maxErrMsgLen))
line := ""
if scanner.Scan() {
line = scanner.Text()
}
err = errors.Errorf("server returned HTTP status %s: %s", httpResp.Status, line)
}
if httpResp.StatusCode/100 == 5 {
return RecoverableError{err, defaultBackoff}
}
if c.retryOnRateLimit && httpResp.StatusCode == http.StatusTooManyRequests {
return RecoverableError{err, retryAfterDuration(httpResp.Header.Get("Retry-After"))}
}
return err
}
// retryAfterDuration returns the duration for the Retry-After header. In case of any errors, it
// returns the defaultBackoff as if the header was never supplied.
func retryAfterDuration(t string) model.Duration {
parsedDuration, err := time.Parse(http.TimeFormat, t)
if err == nil {
s := time.Until(parsedDuration).Seconds()
return model.Duration(s) * model.Duration(time.Second)
}
// The duration can be in seconds.
d, err := strconv.Atoi(t)
if err != nil {
return defaultBackoff
}
return model.Duration(d) * model.Duration(time.Second)
}
// Name uniquely identifies the client.
func (c Client) Name() string {
return c.remoteName
}
// Endpoint is the remote read or write endpoint.
func (c Client) Endpoint() string {
return c.url.String()
}
// Read reads from a remote endpoint.
func (c *Client) Read(ctx context.Context, query *prompb.Query) (*prompb.QueryResult, error) {
c.readQueries.Inc()
defer c.readQueries.Dec()
req := &prompb.ReadRequest{
// TODO: Support batching multiple queries into one read request,
// as the protobuf interface allows for it.
Queries: []*prompb.Query{
query,
},
}
data, err := proto.Marshal(req)
if err != nil {
return nil, errors.Wrapf(err, "unable to marshal read request")
}
compressed := snappy.Encode(nil, data)
httpReq, err := http.NewRequest("POST", c.url.String(), bytes.NewReader(compressed))
if err != nil {
return nil, errors.Wrap(err, "unable to create request")
}
httpReq.Header.Add("Content-Encoding", "snappy")
httpReq.Header.Add("Accept-Encoding", "snappy")
httpReq.Header.Set("Content-Type", "application/x-protobuf")
httpReq.Header.Set("User-Agent", UserAgent)
httpReq.Header.Set("X-Prometheus-Remote-Read-Version", "0.1.0")
ctx, cancel := context.WithTimeout(ctx, c.timeout)
defer cancel()
httpReq = httpReq.WithContext(ctx)
if parentSpan := opentracing.SpanFromContext(ctx); parentSpan != nil {
var ht *nethttp.Tracer
httpReq, ht = nethttp.TraceRequest(
parentSpan.Tracer(),
httpReq,
nethttp.OperationName("Remote Read"),
nethttp.ClientTrace(false),
)
defer ht.Finish()
}
start := time.Now()
httpResp, err := c.Client.Do(httpReq)
if err != nil {
return nil, errors.Wrap(err, "error sending request")
}
defer func() {
io.Copy(ioutil.Discard, httpResp.Body)
httpResp.Body.Close()
}()
c.readQueriesDuration.Observe(time.Since(start).Seconds())
c.readQueriesTotal.WithLabelValues(strconv.Itoa(httpResp.StatusCode)).Inc()
compressed, err = ioutil.ReadAll(httpResp.Body)
if err != nil {
return nil, errors.Wrap(err, fmt.Sprintf("error reading response. HTTP status code: %s", httpResp.Status))
}
if httpResp.StatusCode/100 != 2 {
return nil, errors.Errorf("remote server %s returned HTTP status %s: %s", c.url.String(), httpResp.Status, strings.TrimSpace(string(compressed)))
}
uncompressed, err := snappy.Decode(nil, compressed)
if err != nil {
return nil, errors.Wrap(err, "error reading response")
}
var resp prompb.ReadResponse
err = proto.Unmarshal(uncompressed, &resp)
if err != nil {
return nil, errors.Wrap(err, "unable to unmarshal response body")
}
if len(resp.Results) != len(req.Queries) {
return nil, errors.Errorf("responses: want %d, got %d", len(req.Queries), len(resp.Results))
}
return resp.Results[0], nil
}