push.go: add InitPushWithOptions() function, which allows extending push options without breaking backwards compatibility and without the need to introduce new functions

Overrides https://github.com/VictoriaMetrics/metrics/pull/53
Overrides https://github.com/VictoriaMetrics/metrics/pull/55

Allows specifying authorization headers via PushOptions.Headers for https://github.com/VictoriaMetrics/metrics/issues/36
Allows disabling request body compression via PushOption.DisableCompression for https://github.com/VictoriaMetrics/metrics/pull/41

push.go

@@ -8,11 +8,49 @@ import (
 	"log"
 	"net/http"
 	"net/url"
+	"strings"
 	"time"
 
 	"compress/gzip"
 )
 
+// PushOptions is the list of options, which may be applied to InitPushWithOptions().
+type PushOptions struct {
+	// ExtraLabels is an optional comma-separated list of `label="value"` labels, which must be added to all the metrics before pushing them to pushURL.
+	ExtraLabels string
+
+	// Headers is an optional list of HTTP headers to add to every push request to pushURL.
+	//
+	// Every item in the list must have the form `Header: value`. For example, `Authorization: Custom my-top-secret`.
+	Headers []string
+
+	// Whether to disable HTTP request body compression before sending the metrics to pushURL.
+	//
+	// By default the compression is enabled.
+	DisableCompression bool
+}
+
+// InitPushWithOptions sets up periodic push for globally registered metrics to the given pushURL with the given interval.
+//
+// If pushProcessMetrics is set to true, then 'process_*' and `go_*` metrics are also pushed to pushURL.
+//
+// opts may contain additional configuration options if non-nil.
+//
+// The metrics are pushed to pushURL in Prometheus text exposition format.
+// See https://github.com/prometheus/docs/blob/main/content/docs/instrumenting/exposition_formats.md#text-based-format
+//
+// It is recommended pushing metrics to /api/v1/import/prometheus endpoint according to
+// https://docs.victoriametrics.com/#how-to-import-data-in-prometheus-exposition-format
+//
+// It is OK calling InitPushWithOptions multiple times with different pushURL -
+// in this case metrics are pushed to all the provided pushURL urls.
+func InitPushWithOptions(pushURL string, interval time.Duration, pushProcessMetrics bool, opts *PushOptions) error {
+	writeMetrics := func(w io.Writer) {
+		WritePrometheus(w, pushProcessMetrics)
+	}
+	return initPushWithOptions(pushURL, interval, writeMetrics, opts)
+}
+
 // InitPushProcessMetrics sets up periodic push for 'process_*' metrics to the given pushURL with the given interval.
 //
 // extraLabels may contain comma-separated list of `label="value"` labels, which will be added
@@ -38,7 +76,7 @@ func InitPushProcessMetrics(pushURL string, interval time.Duration, extraLabels
 // extraLabels may contain comma-separated list of `label="value"` labels, which will be added
 // to all the metrics before pushing them to pushURL.
 //
-// If pushProcessMetrics is set to true, then 'process_*' metrics are also pushed to pushURL.
+// If pushProcessMetrics is set to true, then 'process_*' and `go_*` metrics are also pushed to pushURL.
 //
 // The metrics are pushed to pushURL in Prometheus text exposition format.
 // See https://github.com/prometheus/docs/blob/main/content/docs/instrumenting/exposition_formats.md#text-based-format
@@ -55,12 +93,31 @@ func InitPush(pushURL string, interval time.Duration, extraLabels string, pushPr
 	return InitPushExt(pushURL, interval, extraLabels, writeMetrics)
 }
 
+// InitPushWithOptions sets up periodic push for metrics from s to the given pushURL with the given interval.
+//
+// opts may contain additional configuration options if non-nil.
+//
+// The metrics are pushed to pushURL in Prometheus text exposition format.
+// See https://github.com/prometheus/docs/blob/main/content/docs/instrumenting/exposition_formats.md#text-based-format
+//
+// It is recommended pushing metrics to /api/v1/import/prometheus endpoint according to
+// https://docs.victoriametrics.com/#how-to-import-data-in-prometheus-exposition-format
+//
+// It is OK calling InitPushWithOptions multiple times with different pushURL -
+// in this case metrics are pushed to all the provided pushURL urls.
+func (s *Set) InitPushWithOptions(pushURL string, interval time.Duration, opts *PushOptions) error {
+	writeMetrics := func(w io.Writer) {
+		s.WritePrometheus(w)
+	}
+	return initPushWithOptions(pushURL, interval, writeMetrics, opts)
+}
+
 // InitPush sets up periodic push for metrics from s to the given pushURL with the given interval.
 //
 // extraLabels may contain comma-separated list of `label="value"` labels, which will be added
 // to all the metrics before pushing them to pushURL.
 //
-// / The metrics are pushed to pushURL in Prometheus text exposition format.
+// The metrics are pushed to pushURL in Prometheus text exposition format.
 // See https://github.com/prometheus/docs/blob/main/content/docs/instrumenting/exposition_formats.md#text-based-format
 //
 // It is recommended pushing metrics to /api/v1/import/prometheus endpoint according to
@@ -90,14 +147,16 @@ func (s *Set) InitPush(pushURL string, interval time.Duration, extraLabels strin
 // in this case metrics are pushed to all the provided pushURL urls.
 //
 // It is OK calling InitPushExt multiple times with different writeMetrics -
-// in this case all the metrics generated by writeMetrics callbacks are writte to pushURL.
+// in this case all the metrics generated by writeMetrics callbacks are written to pushURL.
 func InitPushExt(pushURL string, interval time.Duration, extraLabels string, writeMetrics func(w io.Writer)) error {
-	if interval <= 0 {
+	opts := &PushOptions{
-		return fmt.Errorf("interval must be positive; got %s", interval)
+		ExtraLabels: extraLabels,
-	}
-	if err := validateTags(extraLabels); err != nil {
-		return fmt.Errorf("invalid extraLabels=%q: %w", extraLabels, err)
 	}
+	return initPushWithOptions(pushURL, interval, writeMetrics, opts)
+}
+
+func initPushWithOptions(pushURL string, interval time.Duration, writeMetrics func(w io.Writer), opts *PushOptions) error {
+	// validate pushURL
 	pu, err := url.Parse(pushURL)
 	if err != nil {
 		return fmt.Errorf("cannot parse pushURL=%q: %w", pushURL, err)
@@ -108,16 +167,53 @@ func InitPushExt(pushURL string, interval time.Duration, extraLabels string, wri
 	if pu.Host == "" {
 		return fmt.Errorf("missing host in pushURL=%q", pushURL)
 	}
-	pushURLRedacted := pu.Redacted()
+
-	c := &http.Client{
+	// validate interval
-		Timeout: interval,
+	if interval <= 0 {
+		return fmt.Errorf("interval must be positive; got %s", interval)
 	}
+
+	// validate ExtraLabels
+	var extraLabels string
+	if opts != nil {
+		extraLabels = opts.ExtraLabels
+	}
+	if err := validateTags(extraLabels); err != nil {
+		return fmt.Errorf("invalid extraLabels=%q: %w", extraLabels, err)
+	}
+
+	// validate Headers
+	var headers http.Header
+	if opts != nil {
+		for _, h := range opts.Headers {
+			n := strings.IndexByte(h, ':')
+			if n < 0 {
+				return fmt.Errorf("missing `:` delimiter in the header %q", h)
+			}
+			name := strings.TrimSpace(h[:n])
+			value := strings.TrimSpace(h[n+1:])
+			headers.Add(name, value)
+		}
+	}
+
+	// validate DisableCompression
+	disableCompression := false
+	if opts != nil {
+		disableCompression = opts.DisableCompression
+	}
+
+	// Initialize metrics for the given pushURL
+	pushURLRedacted := pu.Redacted()
 	pushesTotal := pushMetrics.GetOrCreateCounter(fmt.Sprintf(`metrics_push_total{url=%q}`, pushURLRedacted))
 	pushErrorsTotal := pushMetrics.GetOrCreateCounter(fmt.Sprintf(`metrics_push_errors_total{url=%q}`, pushURLRedacted))
 	bytesPushedTotal := pushMetrics.GetOrCreateCounter(fmt.Sprintf(`metrics_push_bytes_pushed_total{url=%q}`, pushURLRedacted))
 	pushDuration := pushMetrics.GetOrCreateHistogram(fmt.Sprintf(`metrics_push_duration_seconds{url=%q}`, pushURLRedacted))
 	pushBlockSize := pushMetrics.GetOrCreateHistogram(fmt.Sprintf(`metrics_push_block_size_bytes{url=%q}`, pushURLRedacted))
 	pushMetrics.GetOrCreateFloatCounter(fmt.Sprintf(`metrics_push_interval_seconds{url=%q}`, pushURLRedacted)).Set(interval.Seconds())
+
+	c := &http.Client{
+		Timeout: interval,
+	}
 	go func() {
 		ticker := time.NewTicker(interval)
 		var bb bytes.Buffer
@@ -133,14 +229,16 @@ func InitPushExt(pushURL string, interval time.Duration, extraLabels string, wri
 					panic(fmt.Errorf("BUG: cannot write %d bytes to bytes.Buffer: %s", len(tmpBuf), err))
 				}
 			}
-			tmpBuf = append(tmpBuf[:0], bb.Bytes()...)
+			if !disableCompression {
-			bb.Reset()
+				tmpBuf = append(tmpBuf[:0], bb.Bytes()...)
-			zw.Reset(&bb)
+				bb.Reset()
-			if _, err := zw.Write(tmpBuf); err != nil {
+				zw.Reset(&bb)
-				panic(fmt.Errorf("BUG: cannot write %d bytes to gzip writer: %s", len(tmpBuf), err))
+				if _, err := zw.Write(tmpBuf); err != nil {
-			}
+					panic(fmt.Errorf("BUG: cannot write %d bytes to gzip writer: %s", len(tmpBuf), err))
-			if err := zw.Close(); err != nil {
+				}
-				panic(fmt.Errorf("BUG: cannot flush metrics to gzip writer: %s", err))
+				if err := zw.Close(); err != nil {
+					panic(fmt.Errorf("BUG: cannot flush metrics to gzip writer: %s", err))
+				}
 			}
 			pushesTotal.Inc()
 			blockLen := bb.Len()
@@ -150,8 +248,20 @@ func InitPushExt(pushURL string, interval time.Duration, extraLabels string, wri
 			if err != nil {
 				panic(fmt.Errorf("BUG: metrics.push: cannot initialize request for metrics push to %q: %w", pushURLRedacted, err))
 			}
+
+			// Set the needed headers
+			for name, values := range headers {
+				for _, value := range values {
+					req.Header.Add(name, value)
+				}
+			}
 			req.Header.Set("Content-Type", "text/plain")
-			req.Header.Set("Content-Encoding", "gzip")
+
+			if !disableCompression {
+				req.Header.Set("Content-Encoding", "gzip")
+			}
+
+			// Perform the request
 			startTime := time.Now()
 			resp, err := c.Do(req)
 			pushDuration.UpdateDuration(startTime)