Fix: Address Remaining Stringlabels Issues Before Enabling (#4810)

* Address compilation errors

There were some further compilation errors I didn't catch that were
causing failures in the pipeline of the PR where stringlabels were
enabled

* Use StableHash() for backwards compatability

* Ensure that loki.source.kubernetes log tailer computes stable hash for targets

* Ensure that pyroscope.scrape computes stable hash for targets

Author: blewis12

internal/component/discovery/target.go

@@ -308,7 +308,7 @@ func (t Target) groupLabelsHash() uint64 {
 	return t.hashLabelsInOrder(labelsInOrder)
 }
 
-// NOTE 1: This function is copied from Prometheus codebase and adapted to work correctly with Alloy types.
+// NOTE 1: This function is copied from Prometheus codebase (labels.StableHash()) and adapted to work correctly with Alloy types.
 // NOTE 2: It is important to keep the hashing function consistent between Alloy versions in order to have
 //
 //	smooth rollouts without duplicated or missing data. There are tests to verify this behaviour. Do not change it.

internal/component/discovery/target_builder_test.go

@@ -267,7 +267,7 @@ func TestTargetBuilder(t *testing.T) {
 					assert.Equal(t, expected, actual)
 				}
 
-				assert.Equal(t, actual.PromLabels().Hash(), actual.HashLabelsWithPredicate(func(key string) bool {
+				assert.Equal(t, modellabels.StableHash(actual.PromLabels()), actual.HashLabelsWithPredicate(func(key string) bool {
 					return true
 				}), "prometheus and alloy target hash codes should match")
 			}

internal/component/discovery/target_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/grafana/ckit/shard"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/discovery/targetgroup"
+	"github.com/prometheus/prometheus/model/labels"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
@@ -835,7 +836,7 @@ func TestHashLargeLabelSets(t *testing.T) {
 	require.Equal(t, uint64(expectedAllLabelsHash), target.HashLabelsWithPredicate(func(key string) bool {
 		return true
 	}))
-	require.Equal(t, uint64(expectedAllLabelsHash), target.PromLabels().Hash()) // check it matches Prometheus algo
+	require.Equal(t, uint64(expectedAllLabelsHash), labels.StableHash(target.PromLabels())) // check it matches Prometheus algo
 
 	var allNonMetaLabels []string
 	target.ForEachLabel(func(k string, v string) bool {

internal/component/loki/source/kubernetes/kubetail/target.go

@@ -76,7 +76,7 @@ func NewTarget(origLabels labels.Labels, lset labels.Labels) *Target {
 	// Precompute the hash of the target from the public labels and the ID of the
 	// target.
 	hasher := xxhash.New()
-	_, _ = fmt.Fprintf(hasher, "%016d", publicLabels.Hash())
+	_, _ = fmt.Fprintf(hasher, "%016d", labels.StableHash(publicLabels))
 	_, _ = fmt.Fprint(hasher, id)
 	_, _ = fmt.Fprint(hasher, uid)
 	hash := hasher.Sum64()

internal/component/pyroscope/scrape/target.go

@@ -97,7 +97,7 @@ func NewTarget(lbls labels.Labels, params url.Values) *Target {
 	url := urlFromTarget(lbls, params)
 
 	h := fnv.New64a()
-	_, _ = h.Write([]byte(strconv.FormatUint(publicLabels.Hash(), 16)))
+	_, _ = h.Write([]byte(strconv.FormatUint(labels.StableHash(publicLabels), 16)))
 	_, _ = h.Write([]byte(url))
 
 	return &Target{

internal/service/labelstore/service_test.go

@@ -100,11 +100,7 @@ func TestReplaceLocalMappings(t *testing.T) {
 
 func TestReplaceWithoutAddingLocalMapping(t *testing.T) {
 	mapping := New(log.NewNopLogger(), prometheus.DefaultRegisterer)
-	l := labels.Labels{}
-	l = append(l, labels.Label{
-		Name:  "__name__",
-		Value: "test",
-	})
+	l := labels.FromStrings("__name__", "test")
 
 	globalID := mapping.GetOrAddGlobalRefID(l)
 	localRefID := uint64(2)

internal/static/metrics/wal/wal_test.go

@@ -820,8 +820,8 @@ func buildMixedTypeSeries() seriesList {
 			name:    "float_series",
 			samples: []sample{{1, 10.0, nil, nil}, {10, 100.0, nil, nil}},
 			exemplars: []exemplar.Exemplar{
-				{Labels: labels.Labels{{Name: "foobar", Value: "barfoo"}}, Value: float64(10.0), Ts: int64(1), HasTs: true},
-				{Labels: labels.Labels{{Name: "lorem", Value: "ipsum"}}, Value: float64(100.0), Ts: int64(10), HasTs: true},
+				{Labels: labels.FromStrings("foobar", "barfoo"), Value: float64(10.0), Ts: int64(1), HasTs: true},
+				{Labels: labels.FromStrings("lorem", "ipsum"), Value: float64(100.0), Ts: int64(10), HasTs: true},
 			},
 		},
 		// From now on I put -1 into the float to be different from default 0.
@@ -831,32 +831,32 @@ func buildMixedTypeSeries() seriesList {
 			name:    "integer histogram",
 			samples: []sample{{2, -1, tsdbutil.GenerateTestHistogram(1), nil}, {20, -1, tsdbutil.GenerateTestHistogram(100), nil}},
 			exemplars: []exemplar.Exemplar{
-				{Labels: labels.Labels{{Name: "foobar", Value: "barfoo"}}, Value: float64(10.0), Ts: int64(2), HasTs: true},
-				{Labels: labels.Labels{{Name: "lorem", Value: "ipsum"}}, Value: float64(100.0), Ts: int64(20), HasTs: true},
+				{Labels: labels.FromStrings("foobar", "barfoo"), Value: float64(10.0), Ts: int64(2), HasTs: true},
+				{Labels: labels.FromStrings("lorem", "ipsum"), Value: float64(100.0), Ts: int64(20), HasTs: true},
 			},
 		},
 		{
 			name:    "float histogram",
 			samples: []sample{{3, -1, nil, tsdbutil.GenerateTestFloatHistogram(1)}, {30, -1, nil, tsdbutil.GenerateTestFloatHistogram(100)}},
 			exemplars: []exemplar.Exemplar{
-				{Labels: labels.Labels{{Name: "foobar", Value: "barfoo"}}, Value: float64(10.0), Ts: int64(3), HasTs: true},
-				{Labels: labels.Labels{{Name: "lorem", Value: "ipsum"}}, Value: float64(100.0), Ts: int64(30), HasTs: true},
+				{Labels: labels.FromStrings("foobar", "barfoo"), Value: float64(10.0), Ts: int64(3), HasTs: true},
+				{Labels: labels.FromStrings("lorem", "ipsum"), Value: float64(100.0), Ts: int64(30), HasTs: true},
 			},
 		},
 		{
 			name:    "integer NHCB",
 			samples: []sample{{2, -1, tsdbutil.GenerateTestCustomBucketsHistogram(1), nil}, {20, -1, tsdbutil.GenerateTestCustomBucketsHistogram(100), nil}},
 			exemplars: []exemplar.Exemplar{
-				{Labels: labels.Labels{{Name: "foobar", Value: "barfoo"}}, Value: float64(10.0), Ts: int64(2), HasTs: true},
-				{Labels: labels.Labels{{Name: "lorem", Value: "ipsum"}}, Value: float64(100.0), Ts: int64(20), HasTs: true},
+				{Labels: labels.FromStrings("foobar", "barfoo"), Value: float64(10.0), Ts: int64(2), HasTs: true},
+				{Labels: labels.FromStrings("lorem", "ipsum"), Value: float64(100.0), Ts: int64(20), HasTs: true},
 			},
 		},
 		{
 			name:    "float NHCB",
 			samples: []sample{{3, -1, nil, tsdbutil.GenerateTestCustomBucketsFloatHistogram(1)}, {30, -1, nil, tsdbutil.GenerateTestCustomBucketsFloatHistogram(100)}},
 			exemplars: []exemplar.Exemplar{
-				{Labels: labels.Labels{{Name: "foobar", Value: "barfoo"}}, Value: float64(10.0), Ts: int64(3), HasTs: true},
-				{Labels: labels.Labels{{Name: "lorem", Value: "ipsum"}}, Value: float64(100.0), Ts: int64(30), HasTs: true},
+				{Labels: labels.FromStrings("foobar", "barfoo"), Value: float64(10.0), Ts: int64(3), HasTs: true},
+				{Labels: labels.FromStrings("lorem", "ipsum"), Value: float64(100.0), Ts: int64(30), HasTs: true},
 			},
 		},
 	}