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[RW2] Fix type and unit labels propagation in Remote Write v2 receiver to prioritize type-and-unit-labels feature (#17387)

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* fix

Signed-off-by: pipiland2612 <nguyen.t.dang.minh@gmail.com>

* fix nits & update docs

Signed-off-by: pipiland2612 <nguyen.t.dang.minh@gmail.com>

* fix docs

Signed-off-by: pipiland2612 <nguyen.t.dang.minh@gmail.com>

---------

Signed-off-by: pipiland2612 <nguyen.t.dang.minh@gmail.com>
This commit is contained in:
Minh Nguyen 2025-10-31 10:59:03 +02:00 committed by GitHub
parent 84d2007a08
commit c8f1de18a7
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3 changed files with 154 additions and 10 deletions
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10
docs/feature_flags.md
View File

@ -266,7 +266,7 @@ These may not work well if the `<range>` is not a multiple of the collection int
When enabled, Prometheus will start injecting additional, reserved `__type__`
and `__unit__` labels as designed in the [PROM-39 proposal](https://github.com/prometheus/proposals/pull/39).
Those labels are sourced from the metadata structured of the existing scrape and ingestion formats
Those labels are sourced from the metadata structures of the existing scrape and ingestion formats
like OpenMetrics Text, Prometheus Text, Prometheus Proto, Remote Write 2 and OTLP. All the user provided labels with
`__type__` and `__unit__` will be overridden.
@ -274,7 +274,7 @@ PromQL layer will handle those labels the same way __name__ is handled, e.g. dro
on certain operations like `-` or `+` and affected by `promql-delayed-name-removal` feature.
This feature enables important metadata information to be accessible directly with samples and PromQL layer.
It's especially useful for users who:
* Want to be able to select metrics based on type or unit.
@ -284,6 +284,12 @@ It's especially useful for users who:
In future more [work is planned](https://github.com/prometheus/prometheus/issues/16610) that will depend on this e.g. rich PromQL UX that helps
when wrong types are used on wrong functions, automatic renames, delta types and more.
### Behavior with metadata records
When this feature is enabled and the metadata WAL records exists, in an unlikely situation when type or unit are different across those,
the Prometheus outputs intends to prefer the `__type__` and `__unit__` labels values. For example on Remote Write 2.0,
if the metadata record somehow (e.g. due to bug) says "counter", but `__type__="gauge"` the remote time series will be set to a gauge.
## Use Uncached IO
`--enable-feature=use-uncached-io`

23
storage/remote/queue_manager.go
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@ -1954,20 +1954,27 @@ func populateV2TimeSeries(symbolTable *writev2.SymbolsTable, batch []timeSeries,
var nPendingSamples, nPendingExemplars, nPendingHistograms, nPendingMetadata, nUnexpectedMetadata int
for nPending, d := range batch {
pendingData[nPending].Samples = pendingData[nPending].Samples[:0]
if d.metadata != nil {
switch {
case enableTypeAndUnitLabels:
m := schema.NewMetadataFromLabels(d.seriesLabels)
pendingData[nPending].Metadata.Type = writev2.FromMetadataType(m.Type)
pendingData[nPending].Metadata.UnitRef = symbolTable.Symbolize(m.Unit)
pendingData[nPending].Metadata.HelpRef = 0 // Type and unit does not give us help.
// Use Help from d.metadata if available.
if d.metadata != nil {
pendingData[nPending].Metadata.HelpRef = symbolTable.Symbolize(d.metadata.Help)
nPendingMetadata++
}
case d.metadata != nil:
pendingData[nPending].Metadata.Type = writev2.FromMetadataType(d.metadata.Type)
pendingData[nPending].Metadata.HelpRef = symbolTable.Symbolize(d.metadata.Help)
pendingData[nPending].Metadata.UnitRef = symbolTable.Symbolize(d.metadata.Unit)
nPendingMetadata++
} else {
var m schema.Metadata
if enableTypeAndUnitLabels {
m = schema.NewMetadataFromLabels(d.seriesLabels)
}
default:
// Safeguard against sending garbage in case of not having metadata
// for whatever reason.
pendingData[nPending].Metadata.Type = writev2.FromMetadataType(m.Type)
pendingData[nPending].Metadata.UnitRef = symbolTable.Symbolize(m.Unit)
pendingData[nPending].Metadata.Type = writev2.FromMetadataType(model.MetricTypeUnknown)
pendingData[nPending].Metadata.UnitRef = 0
pendingData[nPending].Metadata.HelpRef = 0
}

131
storage/remote/queue_manager_test.go
View File

@ -39,6 +39,7 @@ import (
"github.com/prometheus/prometheus/config"
"github.com/prometheus/prometheus/model/histogram"
"github.com/prometheus/prometheus/model/labels"
"github.com/prometheus/prometheus/model/metadata"
"github.com/prometheus/prometheus/model/relabel"
"github.com/prometheus/prometheus/model/timestamp"
"github.com/prometheus/prometheus/prompb"
@ -2492,6 +2493,136 @@ func TestPopulateV2TimeSeries_TypeAndUnitLabels(t *testing.T) {
}
}
// TestPopulateV2TimeSeries_MetadataAndTypeAndUnit verifies that type and unit labels are properly
// extracted from labels even when d.metadata is not nil (agent mode scenario).
// Regression test for https://github.com/prometheus/prometheus/issues/17381.
func TestPopulateV2TimeSeries_MetadataAndTypeAndUnit(t *testing.T) {
symbolTable := writev2.NewSymbolTable()
testCases := []struct {
name string
typeLabel string
unitLabel string
metadata *metadata.Metadata
expectedType writev2.Metadata_MetricType
expectedUnit string
enableTypeAndUnit bool
}{
{
name: "type_and_unit_no_meta",
typeLabel: "gauge",
unitLabel: "bytes",
metadata: nil,
expectedType: writev2.Metadata_METRIC_TYPE_GAUGE,
expectedUnit: "bytes",
enableTypeAndUnit: true,
},
{
name: "type_no_unit_no_meta",
typeLabel: "counter",
unitLabel: "",
metadata: nil,
expectedType: writev2.Metadata_METRIC_TYPE_COUNTER,
expectedUnit: "",
enableTypeAndUnit: true,
},
{
name: "no_type_and_unit_no_meta",
typeLabel: "gauge",
unitLabel: "bytes",
metadata: nil,
expectedType: writev2.Metadata_METRIC_TYPE_UNSPECIFIED,
expectedUnit: "",
enableTypeAndUnit: false,
},
{
name: "type_and_unit_and_meta",
typeLabel: "gauge",
unitLabel: "bytes",
metadata: &metadata.Metadata{
Type: model.MetricTypeGauge,
Unit: "bytes",
Help: "Test metric",
},
expectedType: writev2.Metadata_METRIC_TYPE_GAUGE,
expectedUnit: "bytes",
enableTypeAndUnit: true,
},
{
name: "type-and-unit-overrides-meta",
typeLabel: "counter",
unitLabel: "requests",
metadata: &metadata.Metadata{
Type: model.MetricTypeGauge,
Unit: "bytes",
Help: "Test metric",
},
expectedType: writev2.Metadata_METRIC_TYPE_COUNTER,
expectedUnit: "requests",
enableTypeAndUnit: true,
},
}
for _, tc := range testCases {
t.Run(tc.name, func(t *testing.T) {
batch := make([]timeSeries, 1)
builder := labels.NewScratchBuilder(3)
// Simulate labels with __type__ and __unit__ as scraped with type-and-unit-labels feature.
builder.Add(labels.MetricName, "test_metric")
if tc.typeLabel != "" {
builder.Add("__type__", tc.typeLabel)
}
if tc.unitLabel != "" {
builder.Add("__unit__", tc.unitLabel)
}
builder.Sort()
batch[0] = timeSeries{
seriesLabels: builder.Labels(),
value: 123.45,
timestamp: time.Now().UnixMilli(),
sType: tSample,
metadata: tc.metadata,
}
pendingData := make([]writev2.TimeSeries, 1)
symbolTable.Reset()
nSamples, nExemplars, nHistograms, nMetadata, _ := populateV2TimeSeries(
&symbolTable,
batch,
pendingData,
false,
false,
tc.enableTypeAndUnit,
)
require.Equal(t, 1, nSamples, "Should have 1 sample")
require.Equal(t, 0, nExemplars, "Should have 0 exemplars")
require.Equal(t, 0, nHistograms, "Should have 0 histograms")
// Verify type is correctly extracted.
require.Equal(t, tc.expectedType, pendingData[0].Metadata.Type,
"Type should match expected for %s", tc.name)
// Verify unit is correctly extracted.
unitRef := pendingData[0].Metadata.UnitRef
symbols := symbolTable.Symbols()
var actualUnit string
if unitRef > 0 && unitRef < uint32(len(symbols)) {
actualUnit = symbols[unitRef]
}
require.Equal(t, tc.expectedUnit, actualUnit, "Unit should match for %s", tc.name)
// Verify metadata count.
if tc.metadata != nil && tc.enableTypeAndUnit {
require.Equal(t, 1, nMetadata, "Should count metadata when d.metadata is provided")
}
})
}
}
func TestHighestTimestampOnAppend(t *testing.T) {
for _, protoMsg := range []remoteapi.WriteMessageType{remoteapi.WriteV1MessageType, remoteapi.WriteV2MessageType} {
t.Run(fmt.Sprint(protoMsg), func(t *testing.T) {