lib/promscrape: fix tests after the commit 658a8742ac

The original commit copies `__address__` label to `instance` label when generating per-target labels as Prometheus does.

See https://www.robustperception.io/life-of-a-label for details.

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/453

lib/promrelabel/relabel.go

@@ -45,12 +45,10 @@ func ApplyRelabelConfigs(labels []prompbmarshal.Label, labelsOffset int, prcs []
 		}
 		labels = tmp
 	}
+	labels = removeEmptyLabels(labels, labelsOffset)
 	if isFinalize {
 		labels = FinalizeLabels(labels[:labelsOffset], labels[labelsOffset:])
 	}
-	// remove empty empty labels after finalize, or we can't tell if the label value
-	// is null character or not set when finalize labels
-	labels = removeEmptyLabels(labels, labelsOffset)
 	SortLabels(labels[labelsOffset:])
 	return labels
 }
@@ -92,29 +90,15 @@ func RemoveMetaLabels(dst, src []prompbmarshal.Label) []prompbmarshal.Label {
 	return dst
 }
 
-// FinalizeLabels finalizes labels according to relabel_config rules.
+// FinalizeLabels removes labels with "__" in the beginning (except of "__name__").
-//
-// It renames `__address__` to `instance` and removes labels with "__" in the beginning.
-//
-// See https://prometheus.io/docs/prometheus/latest/configuration/configuration/#relabel_config
 func FinalizeLabels(dst, src []prompbmarshal.Label) []prompbmarshal.Label {
 	for i := range src {
 		label := &src[i]
 		name := label.Name
-		if !strings.HasPrefix(name, "__") || name == "__name__" {
+		if strings.HasPrefix(name, "__") && name != "__name__" {
+			continue
+		}
 		dst = append(dst, *label)
-			continue
-		}
-		if name == "__address__" {
-			if GetLabelByName(src, "instance") != nil {
-				// The `instance` label is already set. Skip `__address__` label.
-				continue
-			}
-			// Rename `__address__` label to `instance`.
-			labelCopy := *label
-			labelCopy.Name = "instance"
-			dst = append(dst, labelCopy)
-		}
 	}
 	return dst
 }

lib/promrelabel/relabel_test.go

@@ -16,7 +16,7 @@ func TestApplyRelabelConfigs(t *testing.T) {
 			t.Fatalf("unexpected result; got\n%v\nwant\n%v", result, resultExpected)
 		}
 	}
-	t.Run("empty_replabel_configs", func(t *testing.T) {
+	t.Run("empty_relabel_configs", func(t *testing.T) {
 		f(nil, nil, false, nil)
 		f(nil, nil, true, nil)
 		f(nil, []prompbmarshal.Label{
@@ -238,7 +238,7 @@ func TestApplyRelabelConfigs(t *testing.T) {
 				Value: "yyy",
 			},
 			{
-				Name:  "__address__",
+				Name:  "instance",
 				Value: "a.bc",
 			},
 		}, true, []prompbmarshal.Label{
@@ -591,7 +591,7 @@ func TestFinalizeLabels(t *testing.T) {
 			Value: "ass",
 		},
 		{
-			Name:  "__address__",
+			Name:  "instance",
 			Value: "foo.com",
 		},
 	}, []prompbmarshal.Label{

lib/promscrape/config.go

@@ -430,16 +430,7 @@ func appendScrapeWork(dst []ScrapeWork, swc *scrapeWorkConfig, target string, ex
 		// Drop target with '/'
 		return dst, nil
 	}
-	instanceRelabeled := promrelabel.GetLabelValueByName(labels, "instance")
+	addressRelabeled = addMissingPort(schemeRelabeled, addressRelabeled)
-	if instanceRelabeled == "" {
-		// After relabeling, the instance label is set to the value of __address__ by default
-		// if it was not set during relabeling.
-		labels = append(labels, prompbmarshal.Label{
-			Name:  "instance",
-			Value: addressRelabeled,
-		})
-	}
-
 	metricsPathRelabeled := promrelabel.GetLabelValueByName(labels, "__metrics_path__")
 	if metricsPathRelabeled == "" {
 		metricsPathRelabeled = "/metrics"
@@ -455,6 +446,14 @@ func appendScrapeWork(dst []ScrapeWork, swc *scrapeWorkConfig, target string, ex
 		return dst, fmt.Errorf("invalid url %q for scheme=%q (%q), target=%q (%q), metrics_path=%q (%q) for `job_name` %q: %s",
 			scrapeURL, swc.scheme, schemeRelabeled, target, addressRelabeled, swc.metricsPath, metricsPathRelabeled, swc.jobName, err)
 	}
+	// Set missing "instance" label according to https://www.robustperception.io/life-of-a-label
+	if promrelabel.GetLabelByName(labels, "instance") == nil {
+		labels = append(labels, prompbmarshal.Label{
+			Name:  "instance",
+			Value: addressRelabeled,
+		})
+		promrelabel.SortLabels(labels)
+	}
 	dst = append(dst, ScrapeWork{
 		ID:                   atomic.AddUint64(&nextScrapeWorkID, 1),
 		ScrapeURL:            scrapeURL,
@@ -498,7 +497,7 @@ func mergeLabels(job, scheme, target, metricsPath string, extraLabels, externalL
 		m[k] = v
 	}
 	m["job"] = job
-	m["__address__"] = addMissingPort(scheme, target)
+	m["__address__"] = target
 	m["__scheme__"] = scheme
 	m["__metrics_path__"] = metricsPath
 	for k, args := range params {

lib/promscrape/config_test.go

@@ -438,6 +438,10 @@ scrape_configs:
 					Name:  "__vm_filepath",
 					Value: "",
 				},
+				{
+					Name:  "instance",
+					Value: "host1:80",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -472,6 +476,10 @@ scrape_configs:
 					Name:  "__vm_filepath",
 					Value: "",
 				},
+				{
+					Name:  "instance",
+					Value: "host2:80",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -506,6 +514,10 @@ scrape_configs:
 					Name:  "__vm_filepath",
 					Value: "",
 				},
+				{
+					Name:  "instance",
+					Value: "localhost:9090",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -558,6 +570,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "http",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -599,6 +615,10 @@ scrape_configs:
 					Name:  "datacenter",
 					Value: "foobar",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -664,6 +684,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "https",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:443",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -700,6 +724,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "https",
 				},
+				{
+					Name:  "instance",
+					Value: "aaa:443",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -732,6 +760,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "http",
 				},
+				{
+					Name:  "instance",
+					Value: "1.2.3.4:80",
+				},
 				{
 					Name:  "job",
 					Value: "qwer",
@@ -805,6 +837,10 @@ scrape_configs:
 					Name:  "hash",
 					Value: "82",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "prefix:url",
 					Value: "http://foo.bar:1234/metrics",
@@ -904,6 +940,10 @@ scrape_configs:
 					Name:  "__address__",
 					Value: "foo.bar:1234",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "job",
 					Value: "3",
@@ -938,6 +978,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "http",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -982,6 +1026,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "http",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -1016,6 +1064,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "http",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -1056,6 +1108,10 @@ scrape_configs:
 					Name:  "__scheme__",
 					Value: "http",
 				},
+				{
+					Name:  "instance",
+					Value: "foo.bar:1234",
+				},
 				{
 					Name:  "job",
 					Value: "foo",
@@ -1111,6 +1167,10 @@ scrape_configs:
 					Name:  "foo",
 					Value: "bar",
 				},
+				{
+					Name:  "instance",
+					Value: "pp:80",
+				},
 				{
 					Name:  "job",
 					Value: "yyy",

lib/promscrape/scrapework_test.go

@@ -99,7 +99,7 @@ func TestScrapeWorkScrapeInternalSuccess(t *testing.T) {
 		scrape_samples_post_metric_relabeling 0 123
 	`)
 	f(`
-		foo{bar="baz"} 34.45 3
+		foo{bar="baz",empty_label=""} 34.45 3
 		abc -2
 	`, &ScrapeWork{}, `
 		foo{bar="baz"} 34.45 123
@@ -147,6 +147,53 @@ func TestScrapeWorkScrapeInternalSuccess(t *testing.T) {
 		scrape_duration_seconds{job="override"} 0 123
 		scrape_samples_post_metric_relabeling{job="override"} 2 123
 	`)
+	// Empty instance override. See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/453
+	f(`
+		no_instance{instance="",job="some_job",label="val1",test=""} 5555
+		test_with_instance{instance="some_instance",job="some_job",label="val2",test=""} 1555
+	`, &ScrapeWork{
+		HonorLabels: true,
+		Labels: []prompbmarshal.Label{
+			{
+				Name:  "instance",
+				Value: "foobar",
+			},
+			{
+				Name:  "job",
+				Value: "xxx",
+			},
+		},
+	}, `
+		no_instance{job="some_job",label="val1"} 5555 123
+		test_with_instance{instance="some_instance",job="some_job",label="val2"} 1555 123
+		up{instance="foobar",job="xxx"} 1 123
+		scrape_samples_scraped{instance="foobar",job="xxx"} 2 123
+		scrape_duration_seconds{instance="foobar",job="xxx"} 0 123
+		scrape_samples_post_metric_relabeling{instance="foobar",job="xxx"} 2 123
+	`)
+	f(`
+		no_instance{instance="",job="some_job",label="val1",test=""} 5555
+		test_with_instance{instance="some_instance",job="some_job",label="val2",test=""} 1555
+	`, &ScrapeWork{
+		HonorLabels: false,
+		Labels: []prompbmarshal.Label{
+			{
+				Name:  "instance",
+				Value: "foobar",
+			},
+			{
+				Name:  "job",
+				Value: "xxx",
+			},
+		},
+	}, `
+		no_instance{exported_job="some_job",instance="foobar",job="xxx",label="val1"} 5555 123
+		test_with_instance{exported_instance="some_instance",exported_job="some_job",instance="foobar",job="xxx",label="val2"} 1555 123
+		up{instance="foobar",job="xxx"} 1 123
+		scrape_samples_scraped{instance="foobar",job="xxx"} 2 123
+		scrape_duration_seconds{instance="foobar",job="xxx"} 0 123
+		scrape_samples_post_metric_relabeling{instance="foobar",job="xxx"} 2 123
+	`)
 	f(`
 		foo{job="orig",bar="baz"} 34.45
 		bar{job="aa",a="b",job="bb"} -3e4 2345
@@ -205,7 +252,7 @@ func TestScrapeWorkScrapeInternalSuccess(t *testing.T) {
 	`)
 	f(`
 		foo{bar="baz"} 34.44
-		bar{a="b",c="d"} -3e4
+		bar{a="b",c="d",} -3e4
 		dropme{foo="bar"} 334
 		dropme{xxx="yy",ss="dsf"} 843
 	`, &ScrapeWork{
@@ -216,7 +263,7 @@ func TestScrapeWorkScrapeInternalSuccess(t *testing.T) {
 				Value: "xx",
 			},
 			{
-				Name:  "__address__",
+				Name:  "instance",
 				Value: "foo.com",
 			},
 		},

lib/protoparser/prometheus/parser.go

@@ -230,8 +230,8 @@ func unmarshalTags(dst []Tag, s string, noEscapes bool) (string, []Tag, error) {
 			}
 			s = s[n+1:]
 		}
-		// keep null character label value
 		if len(key) > 0 {
+			// Allow empty values (len(value)==0) - see https://github.com/VictoriaMetrics/VictoriaMetrics/issues/453
 			if cap(dst) > len(dst) {
 				dst = dst[:len(dst)+1]
 			} else {

lib/protoparser/prometheus/parser_test.go

@@ -221,6 +221,10 @@ func TestRowsUnmarshalSuccess(t *testing.T) {
 					Key:   "bar",
 					Value: "baz",
 				},
+				{
+					Key:   "aa",
+					Value: "",
+				},
 				{
 					Key:   "x",
 					Value: "y",