143 lines
3.8 KiB
Go
143 lines
3.8 KiB
Go
// Copyright (c) 2017 Arista Networks, Inc.
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// Use of this source code is governed by the Apache License 2.0
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// that can be found in the COPYING file.
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package main
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import (
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"fmt"
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"regexp"
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"strconv"
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"github.com/prometheus/client_golang/prometheus"
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"gopkg.in/yaml.v2"
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)
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// Config is the representation of ocprometheus's YAML config file.
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type Config struct {
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// Per-device labels.
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DeviceLabels map[string]prometheus.Labels
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// Prefixes to subscribe to.
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Subscriptions []string
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// Metrics to collect and how to munge them.
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Metrics []*MetricDef
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}
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// MetricDef is the representation of a metric definiton in the config file.
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type MetricDef struct {
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// Path is a regexp to match on the Update's full path.
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// The regexp must be a prefix match.
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// The regexp can define named capture groups to use as labels.
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Path string
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// Path compiled as a regexp.
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re *regexp.Regexp `deepequal:"ignore"`
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// Metric name.
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Name string
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// Metric help string.
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Help string
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// Label to store string values
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ValueLabel string
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// Default value to display for string values
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DefaultValue float64
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// Does the metric store a string value
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stringMetric bool
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// This map contains the metric descriptors for this metric for each device.
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devDesc map[string]*prometheus.Desc
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// This is the default metric descriptor for devices that don't have explicit descs.
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desc *prometheus.Desc
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}
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// metricValues contains the values used in updating a metric
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type metricValues struct {
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desc *prometheus.Desc
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labels []string
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defaultValue float64
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stringMetric bool
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}
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// Parses the config and creates the descriptors for each path and device.
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func parseConfig(cfg []byte) (*Config, error) {
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config := &Config{
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DeviceLabels: make(map[string]prometheus.Labels),
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}
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if err := yaml.Unmarshal(cfg, config); err != nil {
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return nil, fmt.Errorf("Failed to parse config: %v", err)
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}
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for _, def := range config.Metrics {
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def.re = regexp.MustCompile(def.Path)
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// Extract label names
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reNames := def.re.SubexpNames()[1:]
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labelNames := make([]string, len(reNames))
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for i, n := range reNames {
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labelNames[i] = n
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if n == "" {
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labelNames[i] = "unnamedLabel" + strconv.Itoa(i+1)
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}
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}
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if def.ValueLabel != "" {
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labelNames = append(labelNames, def.ValueLabel)
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def.stringMetric = true
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}
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// Create a default descriptor only if there aren't any per-device labels,
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// or if it's explicitly declared
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if len(config.DeviceLabels) == 0 || len(config.DeviceLabels["*"]) > 0 {
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def.desc = prometheus.NewDesc(def.Name, def.Help, labelNames, config.DeviceLabels["*"])
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}
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// Add per-device descriptors
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def.devDesc = make(map[string]*prometheus.Desc)
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for device, labels := range config.DeviceLabels {
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if device == "*" {
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continue
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}
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def.devDesc[device] = prometheus.NewDesc(def.Name, def.Help, labelNames, labels)
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}
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}
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return config, nil
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}
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// Returns a struct containing the descriptor corresponding to the device and path, labels
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// extracted from the path, the default value for the metric and if it accepts string values.
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// If the device and path doesn't match any metrics, returns nil.
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func (c *Config) getMetricValues(s source) *metricValues {
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for _, def := range c.Metrics {
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if groups := def.re.FindStringSubmatch(s.path); groups != nil {
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if def.ValueLabel != "" {
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groups = append(groups, def.ValueLabel)
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}
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desc, ok := def.devDesc[s.addr]
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if !ok {
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desc = def.desc
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}
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return &metricValues{desc: desc, labels: groups[1:], defaultValue: def.DefaultValue,
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stringMetric: def.stringMetric}
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}
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}
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return nil
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}
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// Sends all the descriptors to the channel.
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func (c *Config) getAllDescs(ch chan<- *prometheus.Desc) {
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for _, def := range c.Metrics {
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// Default descriptor might not be present
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if def.desc != nil {
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ch <- def.desc
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}
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for _, desc := range def.devDesc {
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ch <- desc
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}
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}
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}
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