prometheus

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// Copyright 2023 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package scrape
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import (
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	"bytes"
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	"encoding/binary"
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	"github.com/gogo/protobuf/proto"
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	// Intentionally using client model to simulate client in tests.
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	dto "github.com/prometheus/client_model/go"
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)
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// Write a MetricFamily into a protobuf.
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// This function is intended for testing scraping by providing protobuf serialized input.
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func MetricFamilyToProtobuf(metricFamily *dto.MetricFamily) ([]byte, error) {
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	buffer := &bytes.Buffer{}
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	err := AddMetricFamilyToProtobuf(buffer, metricFamily)
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	if err != nil {
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		return nil, err
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	}
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	return buffer.Bytes(), nil
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}
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// Append a MetricFamily protobuf representation to a buffer.
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// This function is intended for testing scraping by providing protobuf serialized input.
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func AddMetricFamilyToProtobuf(buffer *bytes.Buffer, metricFamily *dto.MetricFamily) error {
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	protoBuf, err := proto.Marshal(metricFamily)
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	if err != nil {
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		return err
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	}
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	varintBuf := make([]byte, binary.MaxVarintLen32)
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	varintLength := binary.PutUvarint(varintBuf, uint64(len(protoBuf)))
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	_, err = buffer.Write(varintBuf[:varintLength])
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	if err != nil {
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		return err
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	}
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	_, err = buffer.Write(protoBuf)
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	return err
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}
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