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// Copyright 2019 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.
// +build !nobtrfs
package collector
import (
"fmt"
"github.com/go-kit/kit/log"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/procfs/btrfs"
)
// A btrfsCollector is a Collector which gathers metrics from Btrfs filesystems.
type btrfsCollector struct {
fs btrfs.FS
logger log.Logger
}
func init() {
registerCollector("btrfs", defaultEnabled, NewBtrfsCollector)
}
// NewBtrfsCollector returns a new Collector exposing Btrfs statistics.
func NewBtrfsCollector(logger log.Logger) (Collector, error) {
fs, err := btrfs.NewFS(*sysPath)
if err != nil {
return nil, fmt.Errorf("failed to open sysfs: %w", err)
}
return &btrfsCollector{
fs: fs,
logger: logger,
}, nil
}
// Update retrieves and exports Btrfs statistics.
// It implements Collector.
func (c *btrfsCollector) Update(ch chan<- prometheus.Metric) error {
stats, err := c.fs.Stats()
if err != nil {
return fmt.Errorf("failed to retrieve Btrfs stats: %w", err)
}
for _, s := range stats {
c.updateBtrfsStats(ch, s)
}
return nil
}
// btrfsMetric represents a single Btrfs metric that is converted into a Prometheus Metric.
type btrfsMetric struct {
name string
desc string
value float64
extraLabel []string
extraLabelValue []string
}
// updateBtrfsStats collects statistics for one bcache ID.
func (c *btrfsCollector) updateBtrfsStats(ch chan<- prometheus.Metric, s *btrfs.Stats) {
const subsystem = "btrfs"
// Basic information about the filesystem.
devLabels := []string{"uuid"}
// Retrieve the metrics.
metrics := c.getMetrics(s)
// Convert all gathered metrics to Prometheus Metrics and add to channel.
for _, m := range metrics {
labels := append(devLabels, m.extraLabel...)
desc := prometheus.NewDesc(
prometheus.BuildFQName(namespace, subsystem, m.name),
m.desc,
labels,
nil,
)
labelValues := []string{s.UUID}
if len(m.extraLabelValue) > 0 {
labelValues = append(labelValues, m.extraLabelValue...)
}
ch <- prometheus.MustNewConstMetric(
desc,
prometheus.GaugeValue,
m.value,
labelValues...,
)
}
}
// getMetrics returns metrics for the given Btrfs statistics.
func (c *btrfsCollector) getMetrics(s *btrfs.Stats) []btrfsMetric {
metrics := []btrfsMetric{
{
name: "info",
desc: "Filesystem information",
value: 1,
extraLabel: []string{"label"},
extraLabelValue: []string{s.Label},
},
{
name: "global_rsv_size_bytes",
desc: "Size of global reserve.",
value: float64(s.Allocation.GlobalRsvSize),
},
}
// Information about devices.
for n, dev := range s.Devices {
metrics = append(metrics, btrfsMetric{
name: "device_size_bytes",
desc: "Size of a device that is part of the filesystem.",
value: float64(dev.Size),
extraLabel: []string{"device"},
extraLabelValue: []string{n},
})
}
// Information about data, metadata and system data.
metrics = append(metrics, c.getAllocationStats("data", s.Allocation.Data)...)
metrics = append(metrics, c.getAllocationStats("metadata", s.Allocation.Metadata)...)
metrics = append(metrics, c.getAllocationStats("system", s.Allocation.System)...)
return metrics
}
// getAllocationStats returns allocation metrics for the given Btrfs Allocation statistics.
func (c *btrfsCollector) getAllocationStats(a string, s *btrfs.AllocationStats) []btrfsMetric {
metrics := []btrfsMetric{
{
name: "reserved_bytes",
desc: "Amount of space reserved for a data type",
value: float64(s.ReservedBytes),
extraLabel: []string{"block_group_type"},
extraLabelValue: []string{a},
},
}
// Add all layout statistics.
for layout, stats := range s.Layouts {
metrics = append(metrics, c.getLayoutStats(a, layout, stats)...)
}
return metrics
}
// getLayoutStats returns metrics for a data layout.
func (c *btrfsCollector) getLayoutStats(a, l string, s *btrfs.LayoutUsage) []btrfsMetric {
return []btrfsMetric{
{
name: "used_bytes",
desc: "Amount of used space by a layout/data type",
value: float64(s.UsedBytes),
extraLabel: []string{"block_group_type", "mode"},
extraLabelValue: []string{a, l},
},
{
name: "size_bytes",
desc: "Amount of space allocated for a layout/data type",
value: float64(s.TotalBytes),
extraLabel: []string{"block_group_type", "mode"},
extraLabelValue: []string{a, l},
},
{
name: "allocation_ratio",
desc: "Data allocation ratio for a layout/data type",
value: s.Ratio,
extraLabel: []string{"block_group_type", "mode"},
extraLabelValue: []string{a, l},
},
}
}
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