Add enable_compression scrape config option

Currently Prometheus will always request gzip compression from the target when sending scrape requests.
HTTP compression does reduce the amount of bytes sent over the wire and so is often desirable.
The downside of compression is that it requires extra resources - cpu & memory.

This also affects the resource usage on the target since it has to compress the response
before sending it to Prometheus.

This change adds a new option to the scrape job configuration block: enable_compression.
The default is true so it remains the same as current Prometheus behaviour.

Setting this option to false allows users to disable compression between Prometheus
and the scraped target, which will require more bandwidth but it lowers the resource
usage of both Prometheus and the target.

Fixes #12319.

Signed-off-by: Łukasz Mierzwa <l.mierzwa@gmail.com>

config/config.go

@@ -158,6 +158,7 @@ var (
 		HonorLabels:             false,
 		HonorTimestamps:         true,
 		HTTPClientConfig:        config.DefaultHTTPClientConfig,
+		EnableCompression:       true,
 	}
 
 	// DefaultAlertmanagerConfig is the default alertmanager configuration.
@@ -582,6 +583,8 @@ type ScrapeConfig struct {
 	MetricsPath string `yaml:"metrics_path,omitempty"`
 	// The URL scheme with which to fetch metrics from targets.
 	Scheme string `yaml:"scheme,omitempty"`
+	// Indicator whether to request compressed response from the target.
+	EnableCompression bool `yaml:"enable_compression"`
 	// An uncompressed response body larger than this many bytes will cause the
 	// scrape to fail. 0 means no limit.
 	BodySizeLimit units.Base2Bytes `yaml:"body_size_limit,omitempty"`

config/config_test.go

@@ -186,6 +186,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -288,6 +289,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(50 * time.Second),
 			ScrapeTimeout:         model.Duration(5 * time.Second),
+			EnableCompression:     true,
 			BodySizeLimit:         10 * units.MiB,
 			SampleLimit:           1000,
 			TargetLimit:           35,
@@ -384,6 +386,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -438,6 +441,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         model.Duration(10 * time.Second),
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -470,6 +474,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -508,6 +513,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -546,6 +552,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -573,6 +580,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -609,6 +617,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -642,6 +651,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -682,6 +692,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -712,6 +723,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -745,6 +757,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -771,6 +784,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -800,6 +814,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       false,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -829,6 +844,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -858,6 +874,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -884,6 +901,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -918,6 +936,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -951,6 +970,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -980,6 +1000,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1009,6 +1030,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1042,6 +1064,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1078,6 +1101,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1133,6 +1157,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1159,6 +1184,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1196,6 +1222,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1239,6 +1266,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1273,6 +1301,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1301,6 +1330,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -1332,6 +1362,7 @@ var expectedConf = &Config{
 			HonorTimestamps:       true,
 			ScrapeInterval:        model.Duration(15 * time.Second),
 			ScrapeTimeout:         DefaultGlobalConfig.ScrapeTimeout,
+			EnableCompression:     true,
 			BodySizeLimit:         globBodySizeLimit,
 			SampleLimit:           globSampleLimit,
 			TargetLimit:           globTargetLimit,
@@ -2060,9 +2091,10 @@ func TestGetScrapeConfigs(t *testing.T) {
 			ScrapeTimeout:   scrapeTimeout,
 			ScrapeProtocols: DefaultGlobalConfig.ScrapeProtocols,
 
-			MetricsPath:      "/metrics",
+			MetricsPath:       "/metrics",
-			Scheme:           "http",
+			Scheme:            "http",
-			HTTPClientConfig: config.DefaultHTTPClientConfig,
+			EnableCompression: true,
+			HTTPClientConfig:  config.DefaultHTTPClientConfig,
 			ServiceDiscoveryConfigs: discovery.Configs{
 				discovery.StaticConfig{
 					{
@@ -2118,6 +2150,8 @@ func TestGetScrapeConfigs(t *testing.T) {
 					MetricsPath: DefaultScrapeConfig.MetricsPath,
 					Scheme:      DefaultScrapeConfig.Scheme,
 
+					EnableCompression: true,
+
 					HTTPClientConfig: config.HTTPClientConfig{
 						TLSConfig: config.TLSConfig{
 							CertFile: filepath.FromSlash("testdata/scrape_configs/valid_cert_file"),
@@ -2158,6 +2192,8 @@ func TestGetScrapeConfigs(t *testing.T) {
 					MetricsPath: DefaultScrapeConfig.MetricsPath,
 					Scheme:      DefaultScrapeConfig.Scheme,
 
+					EnableCompression: true,
+
 					ServiceDiscoveryConfigs: discovery.Configs{
 						&vultr.SDConfig{
 							HTTPClientConfig: config.HTTPClientConfig{
@@ -2210,3 +2246,16 @@ func kubernetesSDHostURL() config.URL {
 	tURL, _ := url.Parse("https://localhost:1234")
 	return config.URL{URL: tURL}
 }
+
+func TestScrapeConfigDisableCompression(t *testing.T) {
+	want, err := LoadFile("testdata/scrape_config_disable_compression.good.yml", false, false, log.NewNopLogger())
+	require.NoError(t, err)
+
+	out, err := yaml.Marshal(want)
+
+	require.NoError(t, err)
+	got := &Config{}
+	require.NoError(t, yaml.UnmarshalStrict(out, got))
+
+	require.Equal(t, false, got.ScrapeConfigs[0].EnableCompression)
+}

config/testdata/scrape_config_disable_compression.good.yml

@@ -0,0 +1,5 @@
+scrape_configs:
+  - job_name: prometheus
+    static_configs:
+      - targets: ['localhost:8080']
+    enable_compression: false

docs/configuration/configuration.md

@@ -237,6 +237,10 @@ job_name: <job_name>
 params:
   [ <string>: [<string>, ...] ]
 
+# If enable_compression is set to "false", Prometheus will request uncompressed
+# response from the scraped target.
+[ enable_compression: <boolean> | default = true ]
+
 # Sets the `Authorization` header on every scrape request with the
 # configured username and password.
 # password and password_file are mutually exclusive.

scrape/scrape.go

@@ -109,6 +109,7 @@ type scrapeLoopOptions struct {
 	scrapeClassicHistograms  bool
 	mrc                      []*relabel.Config
 	cache                    *scrapeCache
+	enableCompression        bool
 }
 
 const maxAheadTime = 10 * time.Minute
@@ -163,6 +164,7 @@ func newScrapePool(cfg *config.ScrapeConfig, app storage.Appendable, offsetSeed
 			offsetSeed,
 			opts.honorTimestamps,
 			opts.trackTimestampsStaleness,
+			opts.enableCompression,
 			opts.sampleLimit,
 			opts.bucketLimit,
 			opts.labelLimits,
@@ -275,6 +277,7 @@ func (sp *scrapePool) reload(cfg *config.ScrapeConfig) error {
 		}
 		honorLabels              = sp.config.HonorLabels
 		honorTimestamps          = sp.config.HonorTimestamps
+		enableCompression        = sp.config.EnableCompression
 		trackTimestampsStaleness = sp.config.TrackTimestampsStaleness
 		mrc                      = sp.config.MetricRelabelConfigs
 	)
@@ -295,11 +298,12 @@ func (sp *scrapePool) reload(cfg *config.ScrapeConfig) error {
 		interval, timeout, err := t.intervalAndTimeout(interval, timeout)
 		var (
 			s = &targetScraper{
-				Target:        t,
+				Target:               t,
-				client:        sp.client,
+				client:               sp.client,
-				timeout:       timeout,
+				timeout:              timeout,
-				bodySizeLimit: bodySizeLimit,
+				bodySizeLimit:        bodySizeLimit,
-				acceptHeader:  acceptHeader(cfg.ScrapeProtocols),
+				acceptHeader:         acceptHeader(cfg.ScrapeProtocols),
+				acceptEncodingHeader: acceptEncodingHeader(enableCompression),
 			}
 			newLoop = sp.newLoop(scrapeLoopOptions{
 				target:                   t,
@@ -309,6 +313,7 @@ func (sp *scrapePool) reload(cfg *config.ScrapeConfig) error {
 				labelLimits:              labelLimits,
 				honorLabels:              honorLabels,
 				honorTimestamps:          honorTimestamps,
+				enableCompression:        enableCompression,
 				trackTimestampsStaleness: trackTimestampsStaleness,
 				mrc:                      mrc,
 				cache:                    cache,
@@ -403,6 +408,7 @@ func (sp *scrapePool) sync(targets []*Target) {
 		}
 		honorLabels              = sp.config.HonorLabels
 		honorTimestamps          = sp.config.HonorTimestamps
+		enableCompression        = sp.config.EnableCompression
 		trackTimestampsStaleness = sp.config.TrackTimestampsStaleness
 		mrc                      = sp.config.MetricRelabelConfigs
 		scrapeClassicHistograms  = sp.config.ScrapeClassicHistograms
@@ -419,12 +425,13 @@ func (sp *scrapePool) sync(targets []*Target) {
 			var err error
 			interval, timeout, err = t.intervalAndTimeout(interval, timeout)
 			s := &targetScraper{
-				Target:        t,
+				Target:               t,
-				client:        sp.client,
+				client:               sp.client,
-				timeout:       timeout,
+				timeout:              timeout,
-				bodySizeLimit: bodySizeLimit,
+				bodySizeLimit:        bodySizeLimit,
-				acceptHeader:  acceptHeader(sp.config.ScrapeProtocols),
+				acceptHeader:         acceptHeader(sp.config.ScrapeProtocols),
-				metrics:       sp.metrics,
+				acceptEncodingHeader: acceptEncodingHeader(enableCompression),
+				metrics:              sp.metrics,
 			}
 			l := sp.newLoop(scrapeLoopOptions{
 				target:                   t,
@@ -434,6 +441,7 @@ func (sp *scrapePool) sync(targets []*Target) {
 				labelLimits:              labelLimits,
 				honorLabels:              honorLabels,
 				honorTimestamps:          honorTimestamps,
+				enableCompression:        enableCompression,
 				trackTimestampsStaleness: trackTimestampsStaleness,
 				mrc:                      mrc,
 				interval:                 interval,
@@ -647,8 +655,9 @@ type targetScraper struct {
 	gzipr *gzip.Reader
 	buf   *bufio.Reader
 
-	bodySizeLimit int64
+	bodySizeLimit        int64
-	acceptHeader  string
+	acceptHeader         string
+	acceptEncodingHeader string
 
 	metrics *scrapeMetrics
 }
@@ -670,6 +679,13 @@ func acceptHeader(sps []config.ScrapeProtocol) string {
 	return strings.Join(vals, ",")
 }
 
+func acceptEncodingHeader(enableCompression bool) string {
+	if enableCompression {
+		return "gzip"
+	}
+	return "identity"
+}
+
 var UserAgent = fmt.Sprintf("Prometheus/%s", version.Version)
 
 func (s *targetScraper) scrape(ctx context.Context) (*http.Response, error) {
@@ -679,7 +695,7 @@ func (s *targetScraper) scrape(ctx context.Context) (*http.Response, error) {
 			return nil, err
 		}
 		req.Header.Add("Accept", s.acceptHeader)
-		req.Header.Add("Accept-Encoding", "gzip")
+		req.Header.Add("Accept-Encoding", s.acceptEncodingHeader)
 		req.Header.Set("User-Agent", UserAgent)
 		req.Header.Set("X-Prometheus-Scrape-Timeout-Seconds", strconv.FormatFloat(s.timeout.Seconds(), 'f', -1, 64))
 
@@ -765,6 +781,7 @@ type scrapeLoop struct {
 	offsetSeed               uint64
 	honorTimestamps          bool
 	trackTimestampsStaleness bool
+	enableCompression        bool
 	forcedErr                error
 	forcedErrMtx             sync.Mutex
 	sampleLimit              int
@@ -1055,6 +1072,7 @@ func newScrapeLoop(ctx context.Context,
 	offsetSeed uint64,
 	honorTimestamps bool,
 	trackTimestampsStaleness bool,
+	enableCompression bool,
 	sampleLimit int,
 	bucketLimit int,
 	labelLimits *labelLimits,
@@ -1102,6 +1120,7 @@ func newScrapeLoop(ctx context.Context,
 		appenderCtx:              appenderCtx,
 		honorTimestamps:          honorTimestamps,
 		trackTimestampsStaleness: trackTimestampsStaleness,
+		enableCompression:        enableCompression,
 		sampleLimit:              sampleLimit,
 		bucketLimit:              bucketLimit,
 		labelLimits:              labelLimits,

scrape/scrape_test.go

@@ -651,6 +651,7 @@ func TestScrapeLoopStopBeforeRun(t *testing.T) {
 		nil, nil, 0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		1,
@@ -726,6 +727,7 @@ func TestScrapeLoopStop(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -805,6 +807,7 @@ func TestScrapeLoopRun(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		time.Second,
@@ -863,6 +866,7 @@ func TestScrapeLoopRun(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		time.Second,
@@ -925,6 +929,7 @@ func TestScrapeLoopForcedErr(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		time.Second,
@@ -986,6 +991,7 @@ func TestScrapeLoopMetadata(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -1046,6 +1052,7 @@ func simpleTestScrapeLoop(t testing.TB) (context.Context, *scrapeLoop) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -1109,6 +1116,7 @@ func TestScrapeLoopFailWithInvalidLabelsAfterRelabel(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -1190,6 +1198,7 @@ func TestScrapeLoopRunCreatesStaleMarkersOnFailedScrape(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -1256,6 +1265,7 @@ func TestScrapeLoopRunCreatesStaleMarkersOnParseFailure(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -1325,6 +1335,7 @@ func TestScrapeLoopCache(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -1411,6 +1422,7 @@ func TestScrapeLoopCacheMemoryExhaustionProtection(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -1528,6 +1540,7 @@ func TestScrapeLoopAppend(t *testing.T) {
 			0,
 			true,
 			false,
+			true,
 			0, 0,
 			nil,
 			0,
@@ -1626,7 +1639,7 @@ func TestScrapeLoopAppendForConflictingPrefixedLabels(t *testing.T) {
 				},
 				nil,
 				func(ctx context.Context) storage.Appender { return app },
-				nil, 0, true, false, 0, 0, nil, 0, 0, false, false, false, nil, false, newTestScrapeMetrics(t),
+				nil, 0, true, false, true, 0, 0, nil, 0, 0, false, false, false, nil, false, newTestScrapeMetrics(t),
 			)
 			slApp := sl.appender(context.Background())
 			_, _, _, err := sl.append(slApp, []byte(tc.exposedLabels), "", time.Date(2000, 1, 1, 1, 0, 0, 0, time.UTC))
@@ -1658,6 +1671,7 @@ func TestScrapeLoopAppendCacheEntryButErrNotFound(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -1719,6 +1733,7 @@ func TestScrapeLoopAppendSampleLimit(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		app.limit, 0,
 		nil,
 		0,
@@ -1799,6 +1814,7 @@ func TestScrapeLoop_HistogramBucketLimit(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		app.limit, 0,
 		nil,
 		0,
@@ -1900,6 +1916,7 @@ func TestScrapeLoop_ChangingMetricString(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -1951,6 +1968,7 @@ func TestScrapeLoopAppendStaleness(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -2005,6 +2023,7 @@ func TestScrapeLoopAppendNoStalenessIfTimestamp(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -2049,6 +2068,7 @@ func TestScrapeLoopAppendStalenessIfTrackTimestampStaleness(t *testing.T) {
 		0,
 		true,
 		true,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -2421,6 +2441,7 @@ metric: <
 				0,
 				true,
 				false,
+				true,
 				0, 0,
 				nil,
 				0,
@@ -2511,6 +2532,7 @@ func TestScrapeLoopAppendExemplarSeries(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -2566,6 +2588,7 @@ func TestScrapeLoopRunReportsTargetDownOnScrapeError(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -2605,6 +2628,7 @@ func TestScrapeLoopRunReportsTargetDownOnInvalidUTF8(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -2657,6 +2681,7 @@ func TestScrapeLoopAppendGracefullyIfAmendOrOutOfOrderOrOutOfBounds(t *testing.T
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -2705,6 +2730,7 @@ func TestScrapeLoopOutOfBoundsTimeError(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -2997,6 +3023,7 @@ func TestScrapeLoop_RespectTimestamps(t *testing.T) {
 		nil, 0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -3041,6 +3068,7 @@ func TestScrapeLoop_DiscardTimestamps(t *testing.T) {
 		nil, 0,
 		false,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -3084,6 +3112,7 @@ func TestScrapeLoopDiscardDuplicateLabels(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -3145,6 +3174,7 @@ func TestScrapeLoopDiscardUnnamedMetrics(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -3411,6 +3441,7 @@ func TestScrapeAddFast(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		0,
@@ -3500,6 +3531,7 @@ func TestScrapeReportSingleAppender(t *testing.T) {
 		0,
 		true,
 		false,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -3705,6 +3737,7 @@ func TestScrapeLoopLabelLimit(t *testing.T) {
 			0,
 			true,
 			false,
+			true,
 			0, 0,
 			&test.labelLimits,
 			0,
@@ -3911,6 +3944,7 @@ func TestScrapeLoopRunCreatesStaleMarkersOnFailedScrapeForTimestampedMetrics(t *
 		0,
 		true,
 		true,
+		true,
 		0, 0,
 		nil,
 		10*time.Millisecond,
@@ -3956,3 +3990,63 @@ func TestScrapeLoopRunCreatesStaleMarkersOnFailedScrapeForTimestampedMetrics(t *
 	require.True(t, value.IsStaleNaN(appender.resultFloats[6].f),
 		"Appended second sample not as expected. Wanted: stale NaN Got: %x", math.Float64bits(appender.resultFloats[6].f))
 }
+
+func TestScrapeLoopCompression(t *testing.T) {
+	simpleStorage := teststorage.New(t)
+	defer simpleStorage.Close()
+
+	metricsText := makeTestMetrics(10)
+
+	for _, tc := range []struct {
+		enableCompression bool
+		acceptEncoding    string
+	}{
+		{
+			enableCompression: true,
+			acceptEncoding:    "gzip",
+		},
+		{
+			enableCompression: false,
+			acceptEncoding:    "identity",
+		},
+	} {
+		t.Run(fmt.Sprintf("compression=%v,acceptEncoding=%s", tc.enableCompression, tc.acceptEncoding), func(t *testing.T) {
+			scraped := make(chan bool)
+
+			ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				require.Equal(t, tc.acceptEncoding, r.Header.Get("Accept-Encoding"), "invalid value of the Accept-Encoding header")
+				fmt.Fprint(w, metricsText)
+				close(scraped)
+			}))
+			defer ts.Close()
+
+			config := &config.ScrapeConfig{
+				JobName:           "test",
+				SampleLimit:       100,
+				Scheme:            "http",
+				ScrapeInterval:    model.Duration(100 * time.Millisecond),
+				ScrapeTimeout:     model.Duration(100 * time.Millisecond),
+				EnableCompression: tc.enableCompression,
+			}
+
+			sp, err := newScrapePool(config, simpleStorage, 0, nil, &Options{}, newTestScrapeMetrics(t))
+			require.NoError(t, err)
+			defer sp.stop()
+
+			testURL, err := url.Parse(ts.URL)
+			require.NoError(t, err)
+			sp.Sync([]*targetgroup.Group{
+				{
+					Targets: []model.LabelSet{{model.AddressLabel: model.LabelValue(testURL.Host)}},
+				},
+			})
+			require.Equal(t, 1, len(sp.ActiveTargets()))
+
+			select {
+			case <-time.After(5 * time.Second):
+				t.Fatalf("target was not scraped")
+			case <-scraped:
+			}
+		})
+	}
+}