lib/promscrape: add support for enable_compression option in the same way as Prometheus does

Updates https://github.com/prometheus/prometheus/pull/13166
Updates https://github.com/prometheus/prometheus/issues/12319

Do not document enable_compression option at docs/sd_configs.md, since vmagent already supports
more clear disable_compression option - see https://docs.victoriametrics.com/vmagent/#scrape_config-enhancements

docs/CHANGELOG.md

@@ -33,6 +33,7 @@ See also [LTS releases](https://docs.victoriametrics.com/LTS-releases.html).
 * FEATURE: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): propagate [label filters](https://docs.victoriametrics.com/keyconcepts/#filtering) via all the [label manipulation functions](https://docs.victoriametrics.com/metricsql/#label-manipulation-functions). For example, `label_del(some_metric{job="foo"}, "instance") + other_metric{pod="bar"}` is now transformed to `label_del(some_metric{job="foo",pod="bar"}, "instance") + other_metric{job="foo",pod="bar"}`. This should reduce the amounts of time series processed during query execution.
 * FEATURE: [Single-node VictoriaMetrics](https://docs.victoriametrics.com/) and `vmstorage` in [VictoriaMetrics cluster](https://docs.victoriametrics.com/cluster-victoriametrics/): expose `vm_last_partition_parts` [metrics](https://docs.victoriametrics.com/#monitoring), which show the number of [parts in the latest partition](https://docs.victoriametrics.com/#storage). These metrics may help debugging query performance slowdown related to the increased number of parts in the last partition, since usually all the ingested data is written to the last partition and all the queries are performed over the recently ingested data, e.g. the last partition.
 * FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add support for `client_id` option into [kuma_sd_configs](https://docs.victoriametrics.com/sd_configs/#kuma_sd_configs) in the same way as Prometheus does. See [this pull request](https://github.com/prometheus/prometheus/pull/13278).
+* FEATURE: [vmagent](https://docs.victoriametrics.com/vmagent.html): add support for `enable_compression` option in [scrape_configs](https://docs.victoriametrics.com/sd_configs/#scrape_configs) in order to be compatible with Prometheus scrape configs. See [this pull request](https://github.com/prometheus/prometheus/pull/13166) and [this feature request](https://github.com/prometheus/prometheus/issues/12319). Note that `vmagent` was always supporting [`disable_compression` option](https://docs.victoriametrics.com/vmagent/#scrape_config-enhancements) before Prometheus added `enable_compression` option.
 * FEATURE: [vmctl](https://docs.victoriametrics.com/vmctl.html): support client-side TLS configuration for [InfluxDB](https://docs.victoriametrics.com/vmctl/#migrating-data-from-influxdb-1x). See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5748). Thanks to @khushijain21 for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5783).
 * FEATURE: [vmctl](https://docs.victoriametrics.com/vmctl.html): support client-side TLS configuration for [Remote Read protocol](https://docs.victoriametrics.com/vmctl/#migrating-data-by-remote-read-protocol). See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5748). Thanks to @khushijain21 for [the pull request](https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5798).
 * FEATURE: [vmui](https://docs.victoriametrics.com/#vmui): preserve [`WITH` templates](https://play.victoriametrics.com/select/accounting/1/6a716b0f-38bc-4856-90ce-448fd713e3fe/expand-with-exprs) when clicking the `prettify query` button at the right side of query input field. See [this feature request](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5383).

lib/promscrape/config.go

@@ -296,6 +296,12 @@ type ScrapeConfig struct {
 	MetricRelabelConfigs []promrelabel.RelabelConfig `yaml:"metric_relabel_configs,omitempty"`
 	SampleLimit          int                         `yaml:"sample_limit,omitempty"`
 
+	// This silly option is needed for compatibility with Prometheus.
+	// vmagent was supporting disable_compression option since the beginning, while Prometheus developers
+	// decided adding enable_compression option in https://github.com/prometheus/prometheus/pull/13166
+	// That's why it needs to be supported too :(
+	EnableCompression *bool `yaml:"enable_compression,omitempty"`
+
 	AzureSDConfigs        []azure.SDConfig        `yaml:"azure_sd_configs,omitempty"`
 	ConsulSDConfigs       []consul.SDConfig       `yaml:"consul_sd_configs,omitempty"`
 	ConsulAgentSDConfigs  []consulagent.SDConfig  `yaml:"consulagent_sd_configs,omitempty"`
@@ -879,6 +885,10 @@ func getScrapeWorkConfig(sc *ScrapeConfig, baseDir string, globalCfg *GlobalConf
 	if sc.SeriesLimit != nil {
 		seriesLimit = *sc.SeriesLimit
 	}
+	disableCompression := sc.DisableCompression
+	if sc.EnableCompression != nil {
+		disableCompression = !*sc.EnableCompression
+	}
 	swc := &scrapeWorkConfig{
 		scrapeInterval:       scrapeInterval,
 		scrapeIntervalString: scrapeInterval.String(),
@@ -898,7 +908,7 @@ func getScrapeWorkConfig(sc *ScrapeConfig, baseDir string, globalCfg *GlobalConf
 		relabelConfigs:       relabelConfigs,
 		metricRelabelConfigs: metricRelabelConfigs,
 		sampleLimit:          sc.SampleLimit,
-		disableCompression:   sc.DisableCompression,
+		disableCompression:   disableCompression,
 		disableKeepAlive:     sc.DisableKeepAlive,
 		streamParse:          sc.StreamParse,
 		scrapeAlignInterval:  sc.ScrapeAlignInterval.Duration(),

lib/promscrape/config_test.go

@@ -1147,6 +1147,7 @@ scrape_configs:
 	f(`
 scrape_configs:
 - job_name: path wo slash
+  enable_compression: false
   static_configs: 
   - targets: ["foo.bar:1234"]
   relabel_configs:
@@ -1161,6 +1162,7 @@ scrape_configs:
 				"instance": "foo.bar:1234",
 				"job":      "path wo slash",
 			}),
+			DisableCompression: true,
 			jobNameOriginal:    "path wo slash",
 		},
 	})