136 lines
3.2 KiB
Go
136 lines
3.2 KiB
Go
package main
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import (
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"database/sql"
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"errors"
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"fmt"
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"math"
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"strconv"
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"strings"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/common/log"
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)
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// Query the pg_settings view containing runtime variables
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func querySettings(ch chan<- prometheus.Metric, db *sql.DB) error {
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log.Debugln("Querying pg_setting view")
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// pg_settings docs: https://www.postgresql.org/docs/current/static/view-pg-settings.html
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//
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// NOTE: If you add more vartypes here, you must update the supported
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// types in normaliseUnit() below
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query := "SELECT name, setting, COALESCE(unit, ''), short_desc, vartype FROM pg_settings WHERE vartype IN ('bool', 'integer', 'real');"
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rows, err := db.Query(query)
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if err != nil {
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return errors.New(fmt.Sprintln("Error running query on database: ", namespace, err))
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}
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defer rows.Close() // nolint: errcheck
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for rows.Next() {
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s := &pgSetting{}
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err = rows.Scan(&s.name, &s.setting, &s.unit, &s.shortDesc, &s.vartype)
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if err != nil {
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return errors.New(fmt.Sprintln("Error retrieving rows:", namespace, err))
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}
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ch <- s.metric()
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}
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return nil
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}
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// pgSetting is represents a PostgreSQL runtime variable as returned by the
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// pg_settings view.
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type pgSetting struct {
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name, setting, unit, shortDesc, vartype string
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}
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func (s *pgSetting) metric() prometheus.Metric {
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var (
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err error
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name = strings.Replace(s.name, ".", "_", -1)
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unit = s.unit // nolint: ineffassign
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shortDesc = s.shortDesc
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subsystem = "settings"
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val float64
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)
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switch s.vartype {
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case "bool":
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if s.setting == "on" {
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val = 1
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}
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case "integer", "real":
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if val, unit, err = s.normaliseUnit(); err != nil {
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// Panic, since we should recognise all units
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// and don't want to silently exlude metrics
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panic(err)
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}
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if len(unit) > 0 {
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name = fmt.Sprintf("%s_%s", name, unit)
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shortDesc = fmt.Sprintf("%s [Units converted to %s.]", shortDesc, unit)
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}
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default:
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// Panic because we got a type we didn't ask for
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panic(fmt.Sprintf("Unsupported vartype %q", s.vartype))
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}
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desc := newDesc(subsystem, name, shortDesc)
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return prometheus.MustNewConstMetric(desc, prometheus.GaugeValue, val)
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}
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func (s *pgSetting) normaliseUnit() (val float64, unit string, err error) {
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val, err = strconv.ParseFloat(s.setting, 64)
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if err != nil {
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return val, unit, fmt.Errorf("Error converting setting %q value %q to float: %s", s.name, s.setting, err)
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}
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// Units defined in: https://www.postgresql.org/docs/current/static/config-setting.html
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switch s.unit {
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case "":
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return
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case "ms", "s", "min", "h", "d":
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unit = "seconds"
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case "kB", "MB", "GB", "TB", "8kB", "16kB", "16MB":
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unit = "bytes"
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default:
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err = fmt.Errorf("Unknown unit for runtime variable: %q", s.unit)
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return
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}
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// -1 is special, don't modify the value
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if val == -1 {
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return
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}
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switch s.unit {
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case "ms":
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val /= 1000
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case "min":
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val *= 60
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case "h":
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val *= 60 * 60
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case "d":
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val *= 60 * 60 * 24
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case "kB":
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val *= math.Pow(2, 10)
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case "MB":
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val *= math.Pow(2, 20)
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case "GB":
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val *= math.Pow(2, 30)
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case "TB":
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val *= math.Pow(2, 40)
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case "8kB":
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val *= math.Pow(2, 13)
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case "16kB":
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val *= math.Pow(2, 14)
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case "16MB":
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val *= math.Pow(2, 24)
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}
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return
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}
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