ebpf_exporter

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package config
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import (
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	"fmt"
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	"os"
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	"path/filepath"
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	"time"
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	"gopkg.in/yaml.v2"
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)
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// Config describes how to configure and extract metrics
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type Config struct {
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	Name    string   `yaml:"name"`
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	Metrics Metrics  `yaml:"metrics"`
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	Kaddrs  []string `yaml:"kaddrs"`
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	BPFPath string
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}
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// Metrics is a collection of metrics attached to a program
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type Metrics struct {
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	Counters   []Counter   `yaml:"counters"`
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	Histograms []Histogram `yaml:"histograms"`
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}
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// Counter is a metric defining prometheus counter
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type Counter struct {
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	Name           string        `yaml:"name"`
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	Help           string        `yaml:"help"`
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	PerfEventArray bool          `yaml:"perf_event_array"`
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	FlushInterval  time.Duration `yaml:"flush_interval"`
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	Labels         []Label       `yaml:"labels"`
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}
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// Histogram is a metric defining prometheus histogram
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type Histogram struct {
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	Name             string              `yaml:"name"`
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	Help             string              `yaml:"help"`
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	BucketType       HistogramBucketType `yaml:"bucket_type"`
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	BucketMultiplier float64             `yaml:"bucket_multiplier"`
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	BucketMin        int                 `yaml:"bucket_min"`
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	BucketMax        int                 `yaml:"bucket_max"`
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	BucketKeys       []float64           `yaml:"bucket_keys"`
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	Labels           []Label             `yaml:"labels"`
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}
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// Label defines how to decode an element from eBPF map key
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// with the list of decoders
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type Label struct {
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	Name     string    `yaml:"name"`
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	Size     uint      `yaml:"size"`
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	Decoders []Decoder `yaml:"decoders"`
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}
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// Decoder defines how to decode value
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type Decoder struct {
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	Name         string            `yaml:"name"`
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	StaticMap    map[string]string `yaml:"static_map"`
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	Regexps      []string          `yaml:"regexps"`
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	AllowUnknown bool              `yaml:"allow_unknown"`
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}
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// HistogramBucketType is an enum to define how to interpret histogram
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type HistogramBucketType string
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const (
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	// HistogramBucketExp2 means histograms with power-of-two keys
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	HistogramBucketExp2 HistogramBucketType = "exp2"
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	// HistogramBucketExp2WithZero means histograms with power-of-two keys where the first key is for zero
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	HistogramBucketExp2WithZero HistogramBucketType = "exp2zero"
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	// HistogramBucketLinear means histogram with linear keys
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	HistogramBucketLinear HistogramBucketType = "linear"
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	// HistogramBucketFixed means histogram with fixed user-defined keys
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	HistogramBucketFixed HistogramBucketType = "fixed"
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)
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// ParseConfigs parses the named configs from the provided configs directory
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func ParseConfigs(dir string, names []string) ([]Config, error) {
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	configs := make([]Config, len(names))
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	for i, name := range names {
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		path := filepath.Join(dir, fmt.Sprintf("%s.yaml", name))
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		f, err := os.Open(path)
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		if err != nil {
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			return nil, fmt.Errorf("error opening %q for config %q: %v", path, name, err)
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		}
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		defer f.Close()
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		err = yaml.NewDecoder(f).Decode(&configs[i])
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		if err != nil {
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			return nil, fmt.Errorf("error parsing %q for config %q: %v", path, name, err)
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		}
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		configs[i].Name = name
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		err = validateConfig(&configs[i])
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		if err != nil {
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			return nil, fmt.Errorf("error validating config: %v", err)
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		}
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		configs[i].BPFPath = filepath.Join(dir, fmt.Sprintf("%s.bpf.o", name))
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	}
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	return configs, nil
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}
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func validateConfig(cfg *Config) error {
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	if cfg.Metrics.Counters == nil && cfg.Metrics.Histograms == nil {
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		return fmt.Errorf("metrics are not defined for config %q", cfg.Name)
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	}
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	for _, counter := range cfg.Metrics.Counters {
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		if counter.Name == "" {
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			return fmt.Errorf("counter %q in config %q lacks name", counter.Name, cfg.Name)
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		}
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		if counter.Help == "" {
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			return fmt.Errorf("counter %q in config %q lacks help", counter.Name, cfg.Name)
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		}
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	}
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	for _, histogram := range cfg.Metrics.Histograms {
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		if histogram.Name == "" {
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			return fmt.Errorf("histogram %q in config %q lacks name", histogram.Name, cfg.Name)
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		}
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		if histogram.Help == "" {
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			return fmt.Errorf("histogram %q in config %q lacks help", histogram.Name, cfg.Name)
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		}
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	}
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	return nil
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}
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