prometheus/web/federate.go

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// Copyright 2015 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package web
import (
"net/http"
"github.com/golang/protobuf/proto"
"github.com/prometheus/prometheus/promql"
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"github.com/prometheus/prometheus/storage/metric"
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"github.com/prometheus/common/expfmt"
"github.com/prometheus/common/model"
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dto "github.com/prometheus/client_model/go"
)
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func (h *Handler) federation(w http.ResponseWriter, req *http.Request) {
h.mtx.RLock()
defer h.mtx.RUnlock()
req.ParseForm()
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metrics := map[model.Fingerprint]metric.Metric{}
for _, s := range req.Form["match[]"] {
matchers, err := promql.ParseMetricSelector(s)
if err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
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for fp, met := range h.storage.MetricsForLabelMatchers(matchers...) {
metrics[fp] = met
}
}
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var (
minTimestamp = model.Now().Add(-promql.StalenessDelta)
format = expfmt.Negotiate(req.Header)
enc = expfmt.NewEncoder(w, format)
)
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w.Header().Set("Content-Type", string(format))
protMetric := &dto.Metric{
Label: []*dto.LabelPair{},
Untyped: &dto.Untyped{},
}
protMetricFam := &dto.MetricFamily{
Metric: []*dto.Metric{protMetric},
Type: dto.MetricType_UNTYPED.Enum(),
}
for fp, met := range metrics {
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globalUsed := map[model.LabelName]struct{}{}
sp := h.storage.LastSamplePairForFingerprint(fp)
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// Discard if sample does not exist or lays before the staleness interval.
if sp == nil || sp.Timestamp.Before(minTimestamp) {
continue
}
// Reset label slice.
protMetric.Label = protMetric.Label[:0]
for ln, lv := range met.Metric {
if ln == model.MetricNameLabel {
protMetricFam.Name = proto.String(string(lv))
continue
}
protMetric.Label = append(protMetric.Label, &dto.LabelPair{
Name: proto.String(string(ln)),
Value: proto.String(string(lv)),
})
if _, ok := h.externalLabels[ln]; ok {
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globalUsed[ln] = struct{}{}
}
}
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// Attach global labels if they do not exist yet.
for ln, lv := range h.externalLabels {
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if _, ok := globalUsed[ln]; !ok {
protMetric.Label = append(protMetric.Label, &dto.LabelPair{
Name: proto.String(string(ln)),
Value: proto.String(string(lv)),
})
}
}
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protMetric.TimestampMs = proto.Int64(int64(sp.Timestamp))
protMetric.Untyped.Value = proto.Float64(float64(sp.Value))
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if err := enc.Encode(protMetricFam); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
}
}