73 lines
2.4 KiB
Go
73 lines
2.4 KiB
Go
// Copyright 2020 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 discovery
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import (
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"fmt"
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"github.com/prometheus/client_golang/prometheus"
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)
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// MetricRegisterer is used by implementations of discovery.Discoverer that need
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// to manage the lifetime of their metrics.
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type MetricRegisterer interface {
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RegisterMetrics() error
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UnregisterMetrics()
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}
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// metricRegistererImpl is an implementation of MetricRegisterer.
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type metricRegistererImpl struct {
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reg prometheus.Registerer
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metrics []prometheus.Collector
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}
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var _ MetricRegisterer = &metricRegistererImpl{}
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// NewMetricRegisterer creates an instance of a MetricRegisterer.
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// Typically called inside the implementation of the NewDiscoverer() method.
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func NewMetricRegisterer(reg prometheus.Registerer, metrics []prometheus.Collector) MetricRegisterer {
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return &metricRegistererImpl{
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reg: reg,
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metrics: metrics,
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}
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}
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// RegisterMetrics registers the metrics with a Prometheus registerer.
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// If any metric fails to register, it will unregister all metrics that
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// were registered so far, and return an error.
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// Typically called at the start of the SD's Run() method.
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func (rh *metricRegistererImpl) RegisterMetrics() error {
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for _, collector := range rh.metrics {
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err := rh.reg.Register(collector)
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if err != nil {
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// Unregister all metrics that were registered so far.
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// This is so that if RegisterMetrics() gets called again,
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// there will not be an error due to a duplicate registration.
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rh.UnregisterMetrics()
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return fmt.Errorf("failed to register metric: %w", err)
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}
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}
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return nil
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}
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// UnregisterMetrics unregisters the metrics from the same Prometheus
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// registerer which was used to register them.
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// Typically called at the end of the SD's Run() method by a defer statement.
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func (rh *metricRegistererImpl) UnregisterMetrics() {
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for _, collector := range rh.metrics {
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rh.reg.Unregister(collector)
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}
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}
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