prometheus/discovery/util.go
Paulin Todev 6de80d7fb0
Allow non-default registry to be used for metrics of SD components
Signed-off-by: Paulin Todev <paulin.todev@gmail.com>
2023-12-11 11:14:26 +00:00

73 lines
2.4 KiB
Go

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